Stebbingdromia, Guinot & Tavares, 2003

Guinot, Danièle & Tavares, Marcos, 2003, A new subfamilial arrangement for the Dromiidae de Haan, 1833, with diagnoses and descriptions of new genera and species (Crustacea, Decapoda, Brachyura), Zoosystema 25 (1), pp. 43-129 : 91-108

Genus Stebbingdromia n. gen.

( Figs 17 ; 18 )

Dromidiopsis – Lewinsohn 1984 pro parte: 104, fig. 3. (Non Dromidiopsis Borradaile, 1900 ; type species: Dromia australiensis Haswell, 1882 ).

Cryptodromiopsis – McLay 1993 pro parte: 188, 190; 2001a: 85, 86. — Hoover 1998: 266. —? Chen & Haibao 2002 pro parte: 102, 541, 542. (Non Cryptodromiopsis Borradaile, 1903 , type species: C. tridens Borradaile, 1903 ).

TYPE AND ONLY SPECIES. — Dromidiopsis plumosa Lewinsohn, 1984 .

ETYMOLOGY. — The new genus is established in honnor of Thomas Roscoe Rede Stebbing (1835-1926) for his contributions to carcinology. Gender: feminine.

DISTRIBUTION. — Stebbingdromia plumosa n. comb., the only species in the genus, is found from the Seychelles Islands (type locality) to Chesterfield Islands, Guam and Hawaii.

DESCRIPTION

Carapace distinctly wider than long; dorsal surface smooth, with regions not defined. Branchial groove marked and forming laterally very deep notch, but without tooth. Anterolateral margins subparallel except anteriorly, armed with two teeth behind exorbital tooth; posterolateral margin very short. Front projecting beyond orbits; rostrum acute, markedly deflexed but visible dorsally; two acute pseudorostral teeth. Orbital margin eave-like; supraorbital margin notched; supraorbital tooth absent or faintly marked; infraorbital tooth triangular, separated from exorbital angle and from inner infraorbital tooth by deep notches; exorbital tooth dentiform. Proepistome raised, in front of wide epistome.

Orbits directed horizontally, deep. Ocular stalk very long and narrow, curved. Antenna: urinal article wider than long, with posterior part of beak broad; basal article with exopodal scale welldeveloped, enlarged; internal angle similarly developed and markedly produced, touching front; following article completely included between these two lateral extensions of basal article. Mxp3 with coxae not completely approximated.

Sternite 3 not visible anteriorly but discernible on each side of sternite 4; sternite 4 with triangular anterior part in contact with coxae of mxp3. When male abdomen applied against ventral surface, sternite 4 completely covered except laterally, i.e. episternite 4; episternite 5 remaining exposed. In females, thoracic sternum regularly sloping backwards, posterior part more bent; in males, posterior sternites, i.e. posterior part of sternite 6, and sternites 7 and 8, abruptly tilted, so they are nearly perpendicular to preceding ones. Female sutures 7/8 short, with apertures of spermathecae apart on very slight prominence between P3 (even in mature females, see McLay 2001a: 85, 86), i.e. not far from gonopores on P3; these apertures (hidden beneath sperm plug in the two examined females) completely exposed and perhaps relatively large.

Abdomen long, reaching mxp3, and relatively wide (probably with pleural parts), triangular in shape, with all segments free; telson rather developed, bluntly triangular. Segment 6 much wider than long, with external margins slightly concave. In males, pleopods present on somites 3-5, showing as uniramous vestiges, rather long and dissimilar. In males, uropods showing as elongated dorsal plates, always visible dorsally, deeply inserted medially between segment 6 and telson, horizontally oriented, relatively movable and slightly projecting beyond outline of abdomen. Abdominal holding by distinctly tuberculate crest on P2 coxa; uropods weakly involved in holding; in addition, presence of rounded granular prominence on P1 coxa.

Chelipeds well-developed, with an epipod; sexual dimorphism marked: in males, fingers strongly downcurved, markedly gaping; dactylus with external surface concave and cutting edge armed with small, molariform proximal tooth; cutting edge of fixed finger armed with several pointed teeth (details not visible on the sketch by Lewinsohn 1984: fig. 3c). P2 and P3 neither lobed nor nodose; propodus long and bearing a small distal propodal spine; inner margin of dactylus with several spines. P4 and P5 reduced, very short, practically similar in size, P5 only slightly longer; dactylus strongly curved; subcheliform apparatus formed by multiple spines: three (P4) or two (P5) distal propodal spines opposing dactyli, and two (P4) or three (P5) spines on outer propodal margins; a large spine on outer dactylus margin on P5; namely a total of six spines on P5; P4 and P5 without spines on inner margin of dactylus.

Male P5 coxa with mobile penial tube.

Male G 1 without apical plate, only with a setose blunt knob. G2 without exopod, and unusual in the Dromiidae (verified in two males, from Seychelles, MNHN-B 8572 and Chesterfield Islands , MNHN-B 22562 ): very short, (shorter than G1), stout, regularly tapering to pointed tip, without styliform, needle-like flagellum ; third distal part corneous.

Carrying behaviour

Despite the long covering of plumose setae, pieces of sponge are used for camouflage ( Hoover 1998: 266).

REMARKS

Because Lewinsohn (1984: 106) was fully aware that the dromiid genera needed to be reviewed, he was uncertain of whether his new species

A

Dromidiopsis plumosa (“different from all other known species”) should have been placed in Dromidiopsis . Lewinsohn’s species was eventually transferred by McLay (1991: 470) first to Dromidia and later ( McLay 1993: 138; 2001a: 85, 86) to Cryptodromiopsis . As a result, D. plumosa has already been placed in three different genera.

Stebbingdromia plumosa n. comb. is the only dromiid (actually Dromiacea) with a relatively short male G2 (slightly shorter than G1) that is stout and lacks the styliform distal part ( Fig. 18B ). In all members of Dromiacea the G2 is typically as long as or longer than G1 and ends in neddle-like flagellum ( Figs 20B ; 23B ).

In the description for the first time of a female of Stebbingdromia plumosa n. comb., an ovigerous one, McLay (2001a: 86) remarked that female sternal sutures 7/8 “end more posteriorly than in other species of the genus [ Cryptodromiopsis ]. This means that the ends of the sutures [apertures of spermathecae] are just below the female gonopores, only about 1 mm away”. This may be regarded as an ancestral condition, such as the arrangement of spines on pereopods (distal propodal spine on P2 and P3; numerous spines on the subcheliform apparatus of P4 and P5).

The apertures of spermathecae are not readily visible in the two available females of Stebbingdromia plumosa n. comb. (ovigerous female, 9.5 × 10.5 mm, Hawaii, Oahu, QM W 21890; female 6.8 × 7.2 mm, Guam, Apra Harbour, ZRC 2000.2112), as both individuals still carry sperm plugs ( Fig. 17C ). We suspect that the spermathecal apertures are relatively large in Stebbingdromia plumosa n. comb., and, if confirmed, this will be another distinctive feature of the genus. The apertures of spermathecae show as very minute pores in the Dromiacea, with few exceptions: for example Sternodromia spinirostris (Miers, 1881) shows narrow oblique slits (see Forest 1974: fig. 6C, pl. 4, fig. 3). The shapes of G2 (thick) and spermathecal apertures (if large) might be regarded as an indication that both G1 and G2 are involved in the insemination process. Two characters of D. plumosa , female sternal sutures 7/8 ending between P3 (versus ending more anteriorly, as far between or in front of P1, in the other Dromiinae n. status) and male vestigial pleopods combined with intercalary dorsal uropods, make this species so different that none of the existing dromiid genera could accommodate it.

Male vestigial pleopods combined with dorsal uropods are relatively rare in the subfamily Dromiinae n. status ( Table 1). This condition occurs only in Moreiradromia n. gen. ( Fig. 14B, C , may be obsolete in larger individuals) and in Dromia pro parte. We observed a long Pl5 and obscure Pl4 and Pl 3 in D. personata ( Linnaeus, 1758) ( Fig. 27A ), more or less short Pl3-Pl 5 in D. bollorei Forest, 1974 ( Fig. 27B ) and D. marmorea Forest, 1974 , and Pl3-Pl5 showing as short papillae in “ Dromia ” wilsoni (Fulton & Grant, 1902) . An analogous condition as in Stebbingdromia n. gen. is found in the subfamily Sphaerodromiinae n. subfam. (see Fig. 22 : but biramous vestigial Pl3-Pl5).

As presently redefined, neither Dromidiopsis sensu nobis, Cryptodromiopsis sensu nobis, nor Dromidia sensu nobis can receive D. plumosa .

Stebbingdromia n. gen can be readily distinguished from Dromidiopsis sensu nobis ( Fig. 6 ), as follows: 1) abdominal segments free (abdominal segments 5 and 6 fused together in Dromidiopsis ); 2) when extended forward, P5 reaching about mid-length of lateral margin of carapace (P5 extremely long, reaching about outer orbital angle in Dromidiopsis ); 3) male G2 short and stout, without styliform flagellum (long and needle-like in Dromidiopsis ); 4) Pl3-Pl5 as vestiges in males (Pl3-Pl5 absent in Dromidiopsis ); 5) merus and carpus of P2 and P3 stout, noticeably high; propodus and dactylus long and thin (merus, carpus, propodus, and dactylus looking similar in Dromidiopsis ); and 6) female sternal sutures 7/8 ending between P3 (between P1 or just behind them, together on central prominence in Dromidiopsis ). In addition, the fronto-orbital region is dissimilar in the two genera.

Differences between Stebbingdromia n. gen. and Cryptodromiopsis sensu nobis ( Fig. 4 ) include: 1) thoracic sternite 3 medially concealed in Stebbingdromia n. gen. (exposed in Cryptodromiopsis ); 2) coxae of mxp3 almost approximated (a distinct gap between them in Cryptodromiopsis ); 3) male thoracic sternite 4 ending in acute tip (truncate in Cryptodromiopsis ); 4) uropods oriented horizontally and weakly involved in abdominal holding (more salient and oriented obliquely, far from prominence on P2 coxa, in Cryptodromiopsis ); 5) Pl3-Pl5 as vestiges (Pl3-Pl5 absent in Cryptodromiopsis ); 6) female apertures of spermathecae between P3 (together on slight tubercle between chelipeds in Cryptodromiopsis ); and 7) male G2 shorter than G1 and without styliform flagellum (long and needle-like in Cryptodromiopsis ).

Differences, other than the carapace and legs, between Stebbingdromia n. gen. and Dromia s.s. include: 1) when folded, male abdomen covering whole sternite 4 (anterior part of sternite 4 exposed in Dromia ); 2) telson longer than wide, triangular (wider than long, rounded/truncate at tip in Dromia ); 3) dorsal uropods projecting only slightly beyond outline of abdomen (strongly salient and movable in Dromia , and with a characteristic small beak overhanging telson, this beak being probably used as stop system for their movement, see Bouchard 2000); 4) apertures of spermathecae apart, between P3 (placed more anteriorly in Dromia ); and 5) G2 short and stout, not needle-like (with styliform flagellum in Dromia ).

Differences, other than the carapace and legs, between Stebbingdromia n. gen. and Moreiradromia n. gen. ( Fig. 14 ) include: 1) thoracic sternite 3 weakly visible dorsally (exposed, may be partly covered by male abdomen, when folded, in Moreiradromia n. gen.); 2) sternite 4 anteriorly triangular (truncate in Moreiradromia n. gen.); 3) male abdominal segment 6 much wider than long (very long, length as much as three quarters of width in Moreiradromia n. gen.); 4) abdominal holding by tuberculate crest on P2 coxa; presence of round prominence on P1 coxa (provided with spine overhanging coxa of P2, which may bear other smaller tubercles, and presence of tubercles or granules on P1, P3 and even P4 coxae in Moreiradromia n. gen.); 5) apertures of spermathecae apart, between P3 (together on prominence placed well beyond articular condyle of P 1 in Moreiradromia n. gen.); and 6) G2 short, not needle-like (long and with a styliform flagellum in Moreiradromia n. gen.).

Differences between Stebbingdromia n. gen. and Hemisphaerodromia ( Fig. 7B ) include: 1) thoracic sternite 4 ending in acute tip in males and, when abdomen flexed, completely covered, except small episternite 4 (rounded, and anterior and episternal parts exposed in Hemisphaerodromia ); 2) telson long, in contact with coxae of mxp3 (shorter, remote from mxp 3 in Hemisphaerodromia ); 3) male segment 6 with external margins slightly concave (deeply hollowed in Hemisphaerodromia ); 4) male pleopods Pl3-Pl5 present as uniramous vestiges, rather long, (absent in Hemisphaerodromia ); 5) abdominal holding by tuberculate crest on P2 coxa; uropods weakly involved; presence of an additional prominence on P1 coxa (only a serrated prominence on P2 coxa tigthly encircled in the space just behind uropods, markedly involved in abdominal holding, in Hemisphaerodromia ); 6) female sternal sutures 7/8 ending apart on slight prominence between P3 (ending together on slight tubercle behind P 2 in Hemisphaerodromia ); and 7) male G2 shorter than G1 and without styliform flagellum (long and needle-like in Hemisphaerodromia ).

It is clear that Stebbingdromia n. gen. is quite unique. For instance, in all the families of Dromiacea, i.e. Homolodromiidae , Dynomenidae and Dromiidae ( Dromiinae n. status, Hypoconchinae n. subfam., and Sphaerodromiinae n. subfam.), the apertures of spermathecae are minute, a condition that is always connected with a styliform and needle-like G2. Stebbingdromia n. gen. is so far the only exception, and it is herein tentatively referred to the Dromiinae n. status. Stebbingdromia n. gen. shares (plesiomorphically?) the following features with the Sphaerodromiinae n. subfam.: 1) short female sternal sutures 7/8, ending between P3, so that the apertures of spermathecae lie beside female gonopores (also found in other basal Podotremata, viz. the Homolodromiidae and Dynomenidae ). In Stebbingdromia n. gen., the very visible female sutures 7/8 and the completely exposed apertures of spermathecae ( Fig. 17C ) actually differ from those found in Sphaerodromia ( Fig. 21C ) and Eodromia ( Fig. 24C ), in which sutures 7/8 and the spermathecae are usually concealed under a lateral heightening of sternite 8; 2) uropods ( Figs 17B ; 18B ) showing as dorsal plates, deeply inserted between abdominal segment 6 and telson, more or less included in outline of abdomen, and not markedly salient. In Sphaerodromia ( Figs 21A ; 22 ) and Eodromia ( Fig. 24A, B ), however, the uropods are immobile and inserted between telson and segment 6, while in Stebbingdromia n. gen. they remain independent and relatively movable. The uropods do not play role in the holding of abdomen in Sphaerodromia or Eodromia whereas in Stebbingdromia n. gen. the role of uropods in the abdominal holding is weak; 3) similar spinulation of walking legs, in particular the long propodi of P2 and P3, which are armed with one distal propodal spine (considered primitive by McLay 1993: 192 in Stebbingdromia plumosa n. comb. and Sphaerodromia spp. ); dactyli of P2 and P3 with numerous spines regularly arranged on inner margin; 4) subcheliform apparatus of P4 and P5, which consists of a large number of propodal spines opposing the dactylus. In Stebbingdromia n. gen., however, the absence of spines on inner margin of P4 and P5 dactyli differs from Sphaerodromia and Eodromia , characterized by the presence of spines; and 5) complete male pleopodal formula (i.e., vestigial Pl3-Pl5 combined with dorsal uropods, Fig. 18C ). The only other known Dromiidae with vestigial male pleopods combined with dorsal uropods are the dromiine genera Moreiradromia n. gen. ( Fig. 14B ) and Dromia pro parte (see Patterns of uropods and vestigial male pleopods 3-5 Fig. 27 ; Table 1).

Nevertheless, several features do not permit the assignation of Stebbingdromia n. gen. to the Sphaerodromiinae n. subfam. They are as follows: 1) thoracic sternum, in particular the shape of sternite 4; 2) male abdomen, in particular segment 6; 3) G2 shorter than G1 and not needlelike in Stebbingdromia n. gen.; 4) coxal structures of the pereopods for abdominal holding, with a tuberculate crest on P2 coxa and a round prominence on P1 coxa, relatively inefficient in Stebbingdromia n. gen. ( Fig. 17A, B ) (versus a prominence on P2 coxae involving telson in anterior part, and an inefficient prominence on P3 coxae covered by abdomen in Sphaerodromia , Fig. 21A, B ); 5) male coxa of P5 with long, independent penial tube in Stebbingdromia n. gen. ( Figs 17A ; 18A ) (male P5 coxa modified into hard process which encloses penis in Sphaerodromia , Figs 23A ; 28 E-G); and 6) mobile uropods (deeply inserted and immobile in Sphaerodromia ). Other differences refer to orbits and eyes, antennae, front, proepistome, and chelipeds (in particular fingers).

The chelipeds of Stebbingdromia n. gen. are peculiar for the Dromiinae n. status. They are markedly sexually dimorphic, with fingers strongly downcurved, very widely gaping, the cutting edge of dactylus concave and armed with several long teeth in males. They do not conform with the chelipeds found in the Hypoconchinae n. subfam. or the Sphaerodromiinae n. subfam. (see below).

The identity of the Cryptodromidiopsis plumosa recorded by Chen & Haibao (2002: 102, fig. 41) could not be verified.

Subfamily HYPOCONCHINAE n. subfam. ( Figs 19 ; 20 ; 28K )

TYPE GENUS. — Hypoconcha Guérin-Méneville, 1854 by present designation. Gender: feminine.

GENUS INCLUDED. — Hypoconcha Guérin-Méneville, 1854 (type species: Cancer parasiticus Linnaeus, 1763 , senior synonym of Cancer sabulosus Herbst, 1799 , see Holthuis 1962).

DESCRIPTION

Carapace generally rounded, hourglass-shaped; dorsal surface flattened, very thin and partly membranous; on each posterior side, large soft area with special texture; branchiostegal region usually soft and of different texture, perhaps constituting ecdysis area. Cervical groove well marked, on two median gastric pits; cardiac region completely delimitated by well-defined cardiac groove. Branchial groove deep and separating hard part of carapace from soft posterior part. Margin of anterior half of carapace usually hairy, appearing as “ciliated”; posterolateral bor- der often markedly concave. Front and lateral margins greatly expanded, covering all parts of head, except antennal flagella, and displacing eyes in ventral location. Front semicircular or slightly truncate in outline, markedly deflected in large triangular ventral plate connected with proepistome. Eyes, antennules, antennae and mouth parts deeply settled in depressions.

Basal article of antennule well-developed. First article of antenna beak-like; basal article noticeably developed, exopodal scale relatively small and internal angle markedly produced; following article deeply inserted inside basal article; remaining articles very small; flagellum long, setose. Orbits small, concealed beneath body. Mxp3 operculiform; coxa developed and closely approximated; merus subtriangular or trapezoidal; exopod noticeably wide, specially in proximal part; crista dentata (on ischium) with small number of corneous teeth.

Ventral surface and legs solid, sometimes hairy (not in Hypoconcha parasitica ( Linnaeus, 1763)) . Gynglymes of sternites 1-3 largely spaced and stepped at lower plane. Sternite 3 only hardly visible (only represented by a small median hollow) or not visible. Sternite 4 showing as well calcified, narrow and elongated plate, in close contact (except medially) with coxae of mxp3, sometimes appearing fixed to them. Episternites 4 and 5 broad and well calcified. In both sexes, posterior thoracic sternites 7 and 8 tilted; in females, anterior sternites 4 and 5 forming horizontal plate, sternites 6-8 bent at right angles, so they are perpendicular to preceding ones; sternite 6 small, rejected laterally, its raised anterior part often surrounding apertures of spermathecae. Sternal suture 4/5 horizontal, well-marked laterally, its trace medially discernible; suture 5/6 oblique, clearly visible; sutures 6/7 and 7/8 very oblique. Female sutures 7/8 relatively short, only present on bent surface of posterior sternites, always ending apart. Apertures of spermathecae located only slightly beyond level of condyle of P3, not very far from female gonopores on P3 ( Fig. 19A ).

Sterno-abdominal depression not noticeably deep and located posteriorly. A large portion of thoracic sternite 4 not concealed by male abdomen, when flexed; episternite 4 greatly exposed. Abdomen with all segments free, usually short (never attaining coxae of mxp3), broad, noticeably widened at level of segments 5 and 6, triangular shaped, and with first segments remaining dorsal, even in males; pleurae may be distinct. In both sexes abdomen bent at right angles about in the middle and disposed into two different planes, so that the posterior part of abdomen lies flat on ventral surface of cephalothorax. This abdominal curvature, less pronounced in males than in females, probably connected with the inclination of two last thoracic sternites, 7 and 8, with regard to preceding ones. Telson triangular, broader than long. Uropods showing as minute ventral plates in both sexes, never visible dorsally, very narrow, rather immovable in males, sexually dimorphic (showing as small and more setiferous lobes in females). Presence of uniramous vestigial male pleopods, varying along the species: Pl3-Pl5 showing as elongated and asymmetrical lobes ( H. californiensis Bouvier, 1898 ; Fig. 19B ), or only as short papillae ( H. panamensis Smith, 1869 ), or indistinct, at least in small specimens ( H. parasitica , H. arcuata Stimpson, 1858 ). Abdomen holding may be provided by structure on P1 coxa, which bears a series of spinous tubercles, the strongest of which overhangs telson ( H. californiensis ); more often, theses structure are absent ( H. arcuata , H. panamensis ); accord- ingly to its curvature at right angles, abdomen flexed halfway and normally applied to thoracic sternum. Female abdomen becoming expanded in ovigerous specimens, with formation of brood chamber.

Chelipeds stout, epipod present, podobranch lacking. Pereopods capable of being folded compactly against body and partly concealed by carapace, with a perfect complementarity of diverse parts. Fixed finger and dactylus of chelipeds armed on prehensile margin with complementary teeth and close along whole length. P2 and P3 not lobed nor nodose; propodus short, never armed with a distal spine; dactylus not strongly curved, without spines or with only very small spines on inner margin. P4 and P5 both reduced (but not coxae) and oriented in a different way than P2 and P3 i.e. directed subdorsally or dorsally, such as in the Dromiinae n. status, but each markedly dissimilar from the other. P4 subdorsal, noticeably robust, much shorter than preceding legs and P5; merus very stout. P5 completely dorsal, much longer than P4. In both P4 and P5, carpus relatively long; propodus short and stout. Dactylus of P4-P5 with a peculiar dactylus, which is upturned, crescent and lunate, extremely mobile, placed in a deep notch of propodus, and ending in corneous hook.

Male P5 coxa with mobile penial tube ( Figs 20A ; 28K ).

G1 not completely closed, without apical plate. G2 very long, styliform, without exopod ( Fig. 20B ).

Carrying behaviour

See under Remarks and under Discussion, Shellcarrying behaviour.

REMARKS

This unusual crab has been known for a long time under the name “Faux Bernard l’Hermite”, given to H. parasitica ( Linnaeus, 1763) by Nicolson (1776: 338, pl. 6, fig. 3) (see Rodriguez 1993: 44). Lamarck (1818: 264) considered this species new but did not describe it. The genus Hypoconcha was established by Guérin-Méneville (1854: 333-343, pl. 5, as H. sabulosa ), when he gave a new key for the “Dromiens”, already welldefined by H. Milne Edwards (1837). Guérin- Méneville (1854) added Hypoconcha to the two other known dromiacean genera, Dromia and Dynomene . Hypoconcha was defined by the flattened carapace, with dorsal surface partly membranous and soft, and by posterior legs ending in crescent-shaped dactylus (carapace more or less inflated and calcified, and P4 and P5 reduced and subcheliform in Dromia , and only P5 modified in Dynomene ). The precise observations and figures of Hypoconcha by Guérin-Méneville (1854: pl. 5, fig. 4) referred to the abdomen longer than the carapace and halfway flexed, the uropods as ventral plates, and the crescent and “retractile” dactylus on P4 and P5 to firmly hold the shell.

Members of the subfamily Hypoconchinae n. subfam. are easily recognized by a number of features: 1) carapace generally rounded, hourglass-shaped; dorsal surface flattened, very thin and partly membranous; ecdysis area probably represented by whole branchiostegal region, at least; 2) front and lateral margins greatly expand- ed, covering all parts of head, except antennal flagella, and displacing eyes in ventral location; front semicircular or slightly truncate in outline; 3) male abdomen widely triangular and flexed at right angles in mid-length; 4) male pleopodal formula complete: Pl3-Pl5 generally as uniramous vestiges in males; 5) uropods showing always as ventral plates; 6) P4 and P5 very dissimilar, with peculiarly contorted and extremely mobile dactyli, which are fitted in deeply notched extremity of propodi ( Guinot & Tavares 2000: 306, fig. 5); 7) condyle of propodi of P4 and P5 modified into prop-up plate, noticeably large, not concealed; gynglyme of propodi deeply notched in order to receive propodal condyle; the set prop-up plate/condyle blocking and preventing carpus from completely folding against merus; 8) female thoracic sternites 7 and 8 tilted drastically, perpendicular in relation to preceding thoracic sternites; and 9) obligate carrier of a lamellibranch shell.

In the Hypoconchinae n. subfam. the female sternal sutures are not as extended forward as in the Dromiinae n. status; the apertures of spermathecae are located beyond level of condyle of P3, not very far from female gonopores on P3, however ( Fig. 19A ).

In the Hypoconchinae n. subfam. the uropods show as ventral plates (not visible dorsally in both males and females) and occur along with vestigial Pl3-Pl 5 in males. The male pleopodal formula is complete, such as in the Sphaerodromiinae n. subfam. (intercalary dorsal plates) and in the Dromiinae n. status pro parte (see Patterns of uropods and vestigial male pleopods 3-5; Table 1). A combination of characters similar to that found in the Hypoconchinae n. subfam., i.e. vestigial pleopods combined with ventral uropods, occurs (with certainty) in Dromidia , Exodromidia and Platydromia .

In the Hypoconchinae n. subfam. neither the uropod nor any other apparent structure holds the abdomen folded beneath cephalothorax. In H. californiensis , however, the P1 coxa bears a series of spiniform tubercules, the strongest one overhanging telson margin. As a result of being disposed onto two planes, the abdomen apparently has its posterior part remaining pressed against thoracic sternum in normal flexion. How the curious keels on P1-P2 coxae of H. californiensis ( Fig. 19A ) play role in holding of abdomen is unknown.

As described in H. arcuata by Kircher (1970: figs 2c, 12e) and in H. parasitica , by Lang & Young (1980: 860, fig. 8A, D, as H. sabulosa (Herbst, 1799)) , the megalopa of the Hypoconchinae n. subfam. is the only one in the family Dromiidae with a single, long, terminal setum on dactylus of P5 (versus several feelers in the Dromiinae n. status, even in Conchoecetes , see Sankolly & Shenoy 1968; Franco 1998; Guinot & Tavares 2000). The single feeler on dactylus of P5 may well prove to be another diagnostic character of the Hypoconchinae n. subfam.

The larval and postlarval features (plesiomorphies?) shared by Hypoconcha and Conchoecetes (see McLay et al. 2001: 739, 744, table 2) are not exclusive to these genera and could not be regard- ed here as an indication of close relationship between Hypoconcha and Conchoecetes . Therefore, the two genera are kept in different subfamilies, Hypoconchinae n. subfam. and Dromiinae n. status, respectively.

Spears et al. (1992: 457) obtained interesting results from sequence-divergence estimates and phylogenies inferred by maximum parsymony analyses of 18S rRNA aligned sequences. As far as Hypoconcha [ H. arcuata ] is concerned, their results suggested that “it seems unlikely that Dromidia [in fact Moreiradromia antillensis n. comb., Dromiinae n. status] and Hypoconcha [ Hypoconchinae n. subfam.], the [only] two dromiid genera used in this study, are as closely related as previously thought”.

The uniqueness of Hypoconcha led McLay (1993: 229) to question whether it belongs or not to the Dromiidae . McLay (2001b: 8) expressed the opinion that Hypoconcha and Conchoecetes shared a common ancestor and belonged to the same particular grouping, whereas Desmodromia was to be kept amongst the other dromiids. Hypoconcha and Conchoecetes share a shell-carrying behaviour, but each with a different method of grapsing the shell (see under Shell-carrying behaviour) and (perhaps) some larval features ( McLay et al. 2001). They also share several characters that is: thin tegument of dorsal carapace (partly membranous in Hypoconcha ), related to shell-carrying; strongly calcified and anteriorly truncated sternite 4. A closer examination of the morphology of Hypoconcha and Conchoecetes reveals, however, that overall similarities are probably superficial ( Guinot & Tavares 2000) and that there is no reason to include Conchoecetes in the subfamily Hypoconchinae n. subfam. The shape of male abdomen, the male uropods (salient dorsal uropods in Conchoecetes , Fig. 3B, C , narrow ventral plates in Hypoconcha , Fig. 19B ) and the condition of sternites 7 and 8 (bent at right angles and bordered laterally by sutures 7/ 8 in female Hypoconcha , Fig. 19A ), the sternite 3 visible dorsally in Conchoecetes ( Fig. 3A, B ) (hardly or not visible dorsally in Hypoconcha , Fig. 19A ), the location of spermathecal apertures (not very far from gonopores on P 3 in Hypoconcha , Fig. 19A , between P 2 in Conchoecetes , Fig. 3A ) clearly distinguish the two genera. A complete male

20 × 21 mm (MNHN-B 21597), coxa of P5, with mobile penial tube; B, México, 27 × 28 mm (EMU 2941), G2, without exopod. Abbreviations: cx5, coxa of P5; pt, penial tube. Scale bars: 1 mm.

pleopodal formula is found in Hypoconcha ( Fig. 19B ), but does not seem present in Conchoecetes ( Fig. 3C ). The similarities of thoracic sternum in Hypoconcha and Conchoecetes are difficult to be appraised: they are probably in close relationship with the shell-carrying behaviour. In male Hypoconcha the well calcified, very flat sternite 4 ( Fig. 19A ) and the short abdomen which only occupies a posterior location ( Rathbun 1937: pl.11, fig. 2) are different from the condition of Conchoecetes ( Fig. 3A, B ).

The taxonomic position of Desmodromia (not examined) is puzzling. As in Hypoconcha the carapace, although not membranous on posterior half, is poorly calcified and flattened; the eaves overhang the eyes; and P4-P5 end in upturned dactylus which supposedly holds a shell. Hypoconcha and Desmodromia differ from one another as follows: 1) epipod present on P1 (absent in Desmodromia ); 2) narrow ventral uropods (dorsal and well-developed in immature female of D. tranterae McLay, 2001 ); 3) female sternal sutures 7/8 ending rather posteriorly in Hypoconcha ( Fig. 19A ) (between P 2 in Desmodromia ); and 4) abdominal holding never involving uropods and provided by structure on P1 coxa, or, more usually, without coxal differentiation (provided by a differentiation of P2 coxa involving uropods in Desmodromia ). It is not known if in Desmodromia (such as in Hypoconcha ) the female thoracic sternites 7 and 8 are tilted, and if the male pleopodal formula is complete and the P5 coxa differentiated into penial mobile tube since males are unknown. The lack of information on the morphology of male abdomen and of details on the P4 and P5 grasping apparatus make it difficult to compare it with the very specialized Hypoconcha .

Presently, the subfamily Hypoconchinae n. subfam. includes six species, all belonging to Hypoconcha Guérin-Méneville, 1854 : H. arcuata Stimpson, 1858 ; H. californiensis Bouvier, 1898 ; H. lowei Rathbun, 1933 ; H. panamensis Smith, 1869 ; Cancer parasiticus Linnaeus, 1763 ; and H. spinosissima Rathbun, 1933 .

The larval development is only known for two species, H. parasitica (see Lang & Young 1980, as H. sabulosa ) and H. arcuata (see Kircher 1970). It is abbreviated to only three zoeal stages and a megalopa. We examined an ovigerous female (6 mm length) of H. parasitica (MNHN-B 28279) with less than 40 rather large eggs.

Subfamily SPHAERODROMIINAE n. subfam. ( Figs 21-24 ; 28 E-G) TYPE GENUS. — Sphaerodromia Alcock, 1899 by present designation (type species: Dromidia kendalli Alcock & Anderson, 1894 by monotypy. Gender: feminine).

GENERA INCLUDED. — Eodromia McLay, 1993 (type species: Eodromia denticulata McLay, 1993 by monotypy); Sphaerodromia Alcock, 1899 .

DESCRIPTION

Carapace longer than wide or as long as wide, subglobose. Lateral margins subparallel; anterolateral margin long, joining buccal cavern instead of exorbital angle, and separated from short posterolateral margin by deep notch. Dorsal surface with regions not defined or almost indistinct; subhepatic area more or less inflated. Branchial groove not marked. Front projecting well beyond orbits. Rostrum noticeably deflexed. Presence of two pseudorostral lobes extending uninterruptedly around supraorbital margin. Orbits oblique, deeply hollowed on lateral sides of carapace; supra- and infraorbital margins entire, forming a sort of eave, orbital border almost continuous. Proepistome widely triangular, in front of welldefined epistome. Ocular stalk short and thick. Antennules with basal article strongly developed. Antenna: first article beak-like; basal article with exopodal scale markedly developed, as long or longer than following article; internal angle weakly or not produced. Mxp3 operculiform; coxae approximated.

Thoracic sternum narrow. Gynglymes of thoracic sternites 1-3 largely spaced from each other, stepped at lower plane. Sternites 1-3 not visible; sternite 4 forming plate overhanging or just touching bases of mxp3 ( Fig. 21A, B ). Episternites 4 and 5 more or less elongated and wide, their gynglymes in almost terminal location. When male abdomen flexed against ventral surface, anterior portion of sternite 4 and lateral part (i.e. episternite 4) exposed, while episternite 5 is completely covered by uropod and hardly or not visible at all ( Fig. 21A ). Sutures 4/5 and 5/6 very short, only lateral and not clearly visible; sutures 6/7 and 7/8 oblique. Female sternal sutures 7/8 short; apertures of spermathecae very minute, behind level of P3 gonopore, located laterally, and either completely exposed ( Sphaerodromia pro parte, for example S. lamellata Crosnier, 1994 ), or concealed under the lateral heightening and fold of sternite 8 ( Sphaerodromia pro parte, for example S. ducoussoi McLay, 1991 , Fig. 21C ; Eodromia , Fig. 24C ).

Abdomen long but not reaching mxp3, once folded; pleural parts well recognizable, all segments free; segment 6 noticeably expanded laterally ( Sphaerodromia , Figs 21A ; 22 ; Eodromia , Fig. 24A, B ); telson long. Vestigial male pleopods 3-5 present, either biramous ( Sphaerodromia , Fig. 22 ) or uniramous ( Eodromia , Fig. 24A ). Male uropods as elongated dorsal plates, exposed but deeply inserted between abdominal segment 6 and telson (the base of which covering uropod), included in the outline of abdomen, viz. not really salient nor movable, occupying a relatively

A

B

large portion of lateral margin of abdomen, playing no role in holding of abdomen ( Sphaerodromia , Figs 21A ; 22 ; Eodromia , Fig. 24A, B ). Dimorphism of uropods marked. Female uropods deeply inserted, rather developed, occupying large part ( Sphaerodromia ) or whole part ( Eodromia ) of abdominal external margin posteriorly to telson, and well visible dorsally ( Sphaerodromia and Eodromia ).

Holding of male abdomen not really efficient when provided by granulous prominence on P2 coxae involving telson in its anterior part ( Sphaerodromia , where the abdomen is loosely retained). Always, a prominence on P3 coxae, covered by abdomen and inefficient ( Fig. 21B ).

Epipod present on chelipeds; podobranch either present ( Sphaerodromia ) or absent ( Eodromia ). P2 and P3 with epipods, with or without podobranchs ( Sphaerodromia ), or without epipods ( Eodromia ).

Chelipeds stout, with fingers close along most of length; dactylus with a large proximal tooth and rest of prehensile margin very thin and smooth; fixed finger with marked proximal teeth and several smaller ones. P2 and P3, very long, neither lobed nor nodose; propodus very long, bearing distal propodal spine. P4 and P5 reduced, shorter than preceding ones, similar in size, oriented in a different way than P2 and P3, only P5 dorsal; subcheliform apparatus formed by multiple distal propodal spines opposing dactyli, three to five; no spines on outer propodal margin; presence of spines on inner margin of P4 and P5 dactylus. P5 without spines on outer dactylus margin.

Male coxa of P5 strongly modified, extended, without movable penial tube, in the two genera ( Sphaerodromia , Figs 23A ; 28E, F ; Eodromia , Fig. 28G ).

G1 with well-developed apical plate. G2 long, with styliform flagellum, exopod present but of variable length ( Sphaerodromia , Fig. 23B ; presence to be verified in Eodromia ).

Carrying behaviour

Large pieces of sponges for Sphaerodromia ( McLay & Crosnier 1991; McLay 1991, 1993;

Crosnier 1994); camouflage data not known in Eodromia .

REMARKS

Differences between Sphaerodromia and other dromiids were already discussed ( McLay & Crosnier 1991; McLay 1991, 1993). They concern the shape of carapace, the presence of podobranchs on pereopods, the presence of distal propodal spine on P2 and P3, and the arrangement of spines to form the subchelate mechanism of P4 and P5. The condition is similar in Eodromia , except that podobranchs and epipods on P2 and P3 are lost, an absence that must be regarded as a more advanced character state ( McLay 1993: 131). A unique character of the Sphaerodromiinae n. subfam. is the long P2 and P3 propodus (with distal spine) and the not strongly curved dactylus. The propodus is shorter and without distal spine, and dactylus curved in the Dromiinae n. status. In the Sphaerodromiinae n. subfam. and Dromiinae n. status, the inner margin of dactylus on P2 and P3 bears several spines (whereas it is smooth, or nearly smooth, in the Hypoconchinae n. subfam.).

The study in this review of morphological structures often neglected before revealed that the sphaerodromiine genera share a combination of characters found nowhere else within the Dromiidae . In Sphaerodromia and Eodromia , the coxa of P5 is extended to form conical expansion in which the penis is completely enclosed. The coxa and penis thus form a single structure ( Figs 23A ; 25B, D ; 28 E-G). In contrast, in the Dromiinae n. status ( Fig. 28 H-J) and Hypoconchinae n. subfam. ( Figs 20A ; 28K ) the male coxa of P5 is not modified to enclose penis and there are two independent structures: the unmodified P5 coxa and the long, sclerotized penis emanating from male gonopore. The dromiine and hypoconchine movable structures, here named “penial tube”, end in soft tip (see Patterns of P5 coxa and penis; Fig. 28 ).

The Sphaerodromiinae n. subfam. ( Figs 21C ; 24C ) have short female sternal sutures 7/8, so the apertures of spermathecae lie, always laterally, in the vicinity of female gonopores on P3, that is, behind level of P3. In Sphaerodromia lamellata , the suture 7/8 is shorter than in S. ducoussoi ( Fig. 21C ) or S. kendalli (Alcock & Anderson, 1894) , and the spermathecal aperture lies posteriorly and is not concealed under raised part of sternite 8. Conversely, all the Dromiinae n. status show extremely long female sutures 7/8, so that the spermathecae open far beyond level of P3, sometimes at level of P1 or beyond. Therefore, in the dromiine females the sternites 7 and 8 occupy much of the ventral surface of cephalothorax, and the thoracic sternum appears dramatically distorted. The only exception is Stebbingdromia plumosa n. comb., where the spermathecae open between P3 ( Fig. 17C ). In the dromiine genera the spermathecae open apart or together, each spermathecal aperture being often positioned on more or less prominent tubercle; in a few genera the spermathecae open on a single tubercle. It is worth noting that the position of the apertures of spermathecae in relation to female gonopores on P3 coxae and the kind of penial structure seem to be related. Thus, in considering the sphaerodromiine condition, the location of the apertures about level of coxae of P3 seems to be connected with a short and non-articulated penis. Conversely, a spermathecal aperture positioned far beyond coxa of P3 appears to be connected with a long, sclerotized and movable penis (penial tube). This condition is found in the Dromiinae n. status (again, the only exception is the atypical Stebbingdromia plumosa n. comb., which has short female sutures 7/8 and penial tube; Figs 17A, C ; 18A ).

The Hypoconchinae n. subfam. show a different combination: sternal sutures 7/8 relatively short ( Fig. 19A ) and the presence of a penial tube ( Figs 20A ; 28K ). In the Hypoconchinae n. subfam. the female sternal sutures 7/8 are slightly extended forward, more than in the Sphaerodromiinae n. subfam. (where they are behind level of P3) but not so far forward as in the Dromiinae n. status. In this respect Dromiinae n. status and Hypoconchinae n. subfam. differ less from one another than from Sphaerodromiinae n. subfam.

The Sphaerodromiinae n. subfam. also shares the absence of spines on outer margin of propodus of P4 and on outer margin of dactylus of P5.

Within the Sphaerodromiinae n. subfam., Sphaerodromia and Eodromia seem to be very closely related to one another as they share a number of characters unique among the Dromiidae . The Sphaerodromia species are relatively large (width more than 65 mm in S. nux Alcock, 1899 ), while Eodromia denticulata McLay, 1993 is very small, with ovigerous females measuring only 4.5 mm width. In Sphaerodromia and Eodromia the basal antennal article bears a long exopodal scale, extending “beyond joint of segments three or four” (Mc Lay 1993: 127), and its internal corner is not or only weakly produced.

In Sphaerodromia ( Fig. 21A, B ) and Eodromia , the long male abdomen covers most part of thoracic sternum, except anterior part of sternite 4 which is in contact with mxp3. In Sphaerodromia ( Figs 21A ; 22 ) and Eodromia ( Fig. 24A, B ), the male abdominal segment 6 is expanded laterally. In Sphaerodromia and Eodromia , no specialized structures are found for an efficient abdominal holding, so the male abdomen is rather loosely retained beneath cephalothorax (the granulous prominences found on P2 and P3 coxae are inefficient).

Sphaerodromia and Eodromia share the subcheliform system formed by multiple distal propodal spines on the dactyli. The minute apertures of spermathecae, at level of P3, are more or less concealed under fold of sternite 8.

Vestigial pleopods are always present in male Sphaerodromiinae n. subfam.: they are biramous in Sphaerodromia ( Fig. 22 ) and uniramous in Eodromia ( Fig. 24A ). In male Sphaerodromiinae n. subfam. Pl3 to Pl5 occur with immovable uropods showing as intercalary dorsal plates. This combination of characters (Pl3-Pl5 combined with dorsal uropods) is known from only a few genera and species of Dromiinae n. status: Dromia pro parte ( Fig. 27 ), Moreiradromia n. gen. ( Fig. 14B ) and Stebbingdromia n. gen. ( Fig. 18C ; Table 1).

The G1 of Sphaerodromia is provided by apical plate, and the G2 ( Fig. 23B ) with exopod. McLay (1993: 132) indicated that the first pairs of pleopods of the male paratype of Eodromia denticulata (8.2 × 7.8 mm; MNHN-B 22545) were “not properly developed”. This specimen has several pairs of pleopods and a P5 coxa not extended: it seems to be an abnormal individual. In a male specimen (4.5 mm width; MNHN-B 26327), the P5 coxa is elongated and both G1 and G2 are developed; an apical plate is clearly present on G1 as in Sphaerodromia , whereas an exopod is not discernible on the G2, which is typically prolonged by styliform flagellum.

Presently, the subfamily Sphaerodromiinae n. subfam. consist of six species including among two genera: 1) Sphaerodromia ( Sphaerodromia brizops McLay & Crosnier, 1991 ; Sphaerodromia ducoussoi ; Dromidia kendalli ; Sphaerodromia lamellata ; Sphaerodromia nux ); 2) Eodromia ( Eodromia denticulata ).

The close relationship between Sphaerodromia and Eodromia , both with many ancestral characteristics, was already noted by McLay (1993: 130, 228). McLay et al. (2001: 741, table 3) recently predicted that the larvae of these two genera should also have primitive features. McLay (1993: 131) noted that the absence of epipods on P2-P3 and of podobranch on chelipeds must be regarded as the more advanced character states of Eodromia .

Our investigation suggests that the Sphaerodromiinae n. subfam. is a basal group within the Dromiidae . Several sphaerodromiine plesiomorphic characters, that is, a male P5 coxa modified and extended in a process (in contrast to a mobile penial tube in the Dromiinae n. status and Hypoconchinae n. subfam.), the male vestigial pleopods on abdominal segments 3-5, the short female sutures 7/8, and the apertures of spermathecae positioned near female gonopores on P3 coxae, are also found in the two other families of Dromiacea, Homolodromiidae Alcock, 1900 and Dynomenidae Ortmann, 1892 . An exopod present on G2, sometimes well-developed ( Sphaerodromia nux , Fig. 23B ) or shorter ( S. brizops , S. lamellata ), is shared with the Dynomenidae , but not with the Homolodromiidae .

It is worth noting that the spermatozoal ultrastructure of Sphaerodromia ( S. lamellata ) allies the genus more closely to the dynomenid Metadynomene tanensis (Yokoya, 1933) than to the advanced dromiid (dromiine) Stimdromia lateralis (Gray, 1831) (Guinot et al. 1998: 91, 93, 94, fig. 8), which is in accordance to the plesiomorphic condition of the Sphaerodromiinae n. subfam.

About the status of Sphaerodromia lethrinusae Takeda & Kurata, 1976 , see under Dromidiopsis sensu nobis.

Whether Parasphaerodromia Spiridonov, 1992 belongs to the Sphaerodromiinae n. subfam. is not certain but seems unlikely. Based on the original description of Parasphaerodromia subglobosa Spiridonov, 1992 , type species and the only representative of the genus, McLay (1993: 122, 183, 184) synonymized the species with Dromidia spongiosa , now Platydromia spongiosa n. comb. (see above, Fig. 15 ), but furnished no arguments for doing so. As a result, Parasphaerodromia is merged into Platydromia Brocchi, 1877 . The synonymy between Parasphaerodromia subglobosa Spiridonov, 1992 and Platydromia spongiosa n. comb. shall very likely to be confirmed in the future (see above, under Platydromia ). Our view is that the establishment of dromiid taxa necessitates the adequate description and illustration of essential characters such as the thoracic sternum and uropods; details of the carapace and legs alone are usually insufficient.

Figures

FIG. 17. — Stebbingdromia plumosa (Lewinsohn, 1984) n. comb.; A, B, Chesterfield Islands, CORAIL 2, stn DW 84, McLay det. Cryptodromiopsis plumosa, 11.3 × 13.3 mm (MNHN-B 22562); A, thoracic sternum, two front views; B, abdomen, dorsal view; C, Hawaii, Oahu, McLay det. C. plumosa, ovigerous 9.5 × 10.5 mm (QM W21890), thoracic sternum and spermathecae; note large apertures of spermathecae at level of P3, concealed by sperm plug. Abbreviations: a6, abdominal segment 6; cx1-cx5, coxae of P1- P5; e4, e5, episternites 4, 5; g, granules on rounded prominence on P1 coxa; mxp3, external maxilliped; o, female gonopore; pr, holding prominence; pt, penial tube; sp, sperm plug; t, telson; u, uropod; 1-3, sternites 1-3; 4-8, sternites 4-8; 4/5-7/8, thoracic sternal sutures 4/5-7/8. Dotted line indicates difference in level. Scale bar: 2 mm.

FIG. 18. — Stebbingdromia plumosa (Lewinsohn, 1984) n. comb., Chesterfield Islands, CORAIL 2, stn DW 84, McLay det. Cryptodromiopsis plumosa, 11.3 × 13.3 mm (MNHN-B 22562); A, coxa of P5, with penis as mobile tube; B, G2, without styliform flagellum (corneous part stippled); C, abdomen, ventral view. Abbreviations: a3-a6, abdominal segments 3-6; cx5, coxa of P5; pt, penial tube; t, telson; u, uropod; v3-v5, vestigial pleopods 3-5. Scale bars: 1 mm.

FIG. 20. — Hypoconcha panamensis Smith, 1869; A, Panama,

FIG. 23. — Sphaerodromia nux Alcock, 1899,Madagascar, 60 × 67 mm (MNHN-B 6872); A, coxa of P5, modified and elongat- ed into process enclosing penis and not forming penial tube; B, G2, with long exopod. Abbreviations: cx5, coxae of P5; e, elongation of P5 coxa enclosing penis. Scale bars: 1 mm.

FIG. 14. — A, B, Moreiradromia antillensis (Stimpson, 1858) n. comb.; A, South America, Calypso, 14 × 15 mm (MNHN-B 12717), thoracic sternum, two front views, and spermathecae; B, Florida, 16 × 15 mm (MNHN-B 12753), ventral surface of abdomen, with vestigial pleopods on segments 3-5; C, Moreiradromia sarraburei (Rathbun, 1910) n. comb., San José Island, Diguet coll., McLay det. Cryptodromiopsis larraburei, 18.4 × 19 mm (MNHN-B 12761), thoracic sternum with abdomen (tilted for clarity). Abbreviations: a6, abdominal segment 6; cx1-cx5, coxae of P1-P5; g, granules on P1 coxa; mxp3, external maxilliped; o, female gonopore; pr, holding spiniform prominence; s, aperture of spermatheca; t, telson; u, uropod; v3-v5, vestigial pleopods 3-5; 1-2, sternites 1-2; 3-8, sternites 3-8; 4/5-7/8, thoracic sternal sutures 4/5-7/8. Dotted line indicates difference in level. Scale bars: 1 mm.

FIG. 27. — Dromia Weber, 1795, uropods and vestigial male pleopods on segments 3-5 with details on each side; A, Dromia personata (Linnaeus, 1758), Cape Fréhel, 47 × 59 mm (MNHN-B 22049); B, D. bollorei Forest, 1974, Ivory Coast, 71.5 × 85 mm, paratype (MNHN-B 21932). Abbreviations: a3-a6, abdominal segments 3-6; t, telson; u, uropod; v3-v5, vestigial pleopods 3-5. Scale bars: A, B, 5 mm; details, 1 mm.

FIG. 22. — Sphaerodromia Alcock, 1899, biramous vestigial male pleopods on segments 3-5 with details on each side; A, S. ducoussoi McLay, 1991, Tuamotu, Tuanake, 43.2 × 43 mm, holotype (MNHN-B 22172); B, S. nux Alcock, 1899, Madagascar, 60 × 67 mm (MNHN-B 6872). Abbreviations: a3, a6, abdominal segments 3, 6; t, telson; u, uropod; v3-v5, biramous vestigial pleopods 3-5. Scale bars: A, 2.5 mm; B, 2 mm.

FIG. 6. — A, Dromidiopsis tridentata Borradaile, 1903, New Caledonia, LAGON, stn DW 554, ovigerous 12.7 × 12 mm (MNHN-B 22550), thoracic sternum and spermathecae; B, D. australiensis (Haswell, 1882), Australia, Queensland, Cape Bedford, D. J. G. Griffin det., 15.4 × 14 mm (AM P16598), thoracic sternum with abdomen. Abbreviations: a5, a6, abdominal segments 5, 6; cx1- cx5, coxae of P1-P5; e4, episternite 4; mxp3, external maxilliped; o, female gonopore; pr, holding prominence; s, aperture of spermatheca; t, telson (setae covering sternite 4 not shown); u, uropod; 4-8, sternites 4-8; 4/5-7/8, thoracic sternal sutures 4/5-7/8. Dotted line indicates difference in level. Scale bars: 2 mm.

FIG. 4. — Cryptodromiopsis tridens Borradaile, 1903, Polynesia, Moorea, 1979, C. Bouchon coll., 6.2 × 7.5 mm (MNHN-B 22579); thoracic sternum with (A) and without (B) abdomen. Abbreviations:a6, abdominal segment 6; cx1-cx5, coxae of P1-P5; e4, e5, episternites 4, 5; mxp3, external maxilliped; pr, holding prominence; pt, penial tube; t, telson; u, uropod; 1-3, sternites 1-3; 4-8, sternites 4-8; 6/7-7/8, thoracic sternal sutures 6/7-7/8. Scale bar: 1 mm.

FIG. 7. — A, Epipedodromia thomsoni (Fulton & Grant,1902),Australia,Victoria, Port Phillip, 9 × 11 mm (BM 1884-39), thoracic sternum and spermathecae; B, Hemisphaerodromia monodus (Stebbing, 1918), Madagascar, Fort-Dauphin,Decary coll., det.H. abellana Barnard, 1954, 16 × 18 mm (MNHN-B 12725), thoracic sternum and spermathecae.Abbreviations: cx1-cx5, coxae of P1-P5; e4, e5, episternites 4, 5; mxp3, external maxilliped; o, female gonopore; r, medial ridge; s, aperture of spermatheca; 1-3, sternites 1-3; 4-8, sternites 4-8; 4/5-7/8, thoracic sternal sutures 4/5-7/8. Dotted line indicates difference in level.Scale bars: 2.5 mm.

FIG. 21. — Sphaerodromia ducoussoi McLay, 1991; A, B, Tuamotu, 43.2 × 43 mm, holotype (MNHN-B 22172), thoracic sternum without and with abdomen; C, Tuamotu, Mururoa, 41.4 × 40.9 mm, paratype (MNHN-B 22173), spermathecae, behind level of P3. Abbreviations: a6, abdominal segment 6; cx1-cx4, coxae of P1-P4; e4, e5, episternites 4, 5; i, prominence on P3 coxa, covered by abdomen and inefficient for abdominal holding; o, female gonopore; pr, holding prominence; s, aperture of spermatheca; t, telson; u, uropod; 4-8, sternites 4-8; 4/5-7/8, thoracic sternal sutures 4/5-7/8. Dotted line indicates difference in level. Scale bars: 2.5 mm.

FIG. 24. — Eodromia denticulata McLay, 1993, Indonesia, Kai Islands, Tanimbar Island, KARUBAR (MNHN-B 26327); A, B, 4.9 × 4.5 mm, abdomen, ventral and dorsal views; note elongated uniramous vestigial pleopods on segments 3-5; C, ovigerous 5 × 4.5 mm, thoracic sternum and spermathecae, with aperture at level of P3. Abbreviations: a3-a6, abdominal segments 3-6; cx2- cx5, coxae of P2-P5; o, female gonopore; s, aperture of spermatheca; t, telson; u, uropod; v3-v5, vestigial pleopods 3-5; 6-8, sternites 6-8; 6/7, 7/8, thoracic sternal sutures 6/7, 7/8. Scale bars: 0.5 mm.

FIG. 28. — Patterns of male coxa of P5 in the Dromiacea de Haan, 1833; A-G, pattern with coxa modified and elongated into process enclosing penis and not forming penial tube; A, B, Homolodromiidae Alcock, 1900; A, Homolodromia paradoxa A. Milne Edwards, 1880, Bahamas, Gerda, stn 190, 24 × 15 mm (RMNH); B, Dicranodromia mahieuxii A. Milne Edwards, 1883, Bay of Biscay, Le Travailleur, stn 9, 9 × 6.5 mm, holotype (MNHN-B 21681); C, D, Dynomenidae Ortmann, 1892; C, Dynomene hispida Guérin- Méneville, 1832, New Caledonia, 8.8 × 11.5 mm (MNHN-B 22091); D, Paradynomene tuberculata Sakai, 1963, New Caledonia, 11 mm width (MNHN-B 24780); E-G, Sphaerodromiinae n. subfam. (Dromiidae); E, Sphaerodromia ducoussoi McLay, 1991, Tuamotu, 43.2 × 43 mm, holotype (MNHN-B 22172); F, Sphaerodromia lamellata Crosnier, 1994, New Caledonia, 47.8 × 42.6 mm, holotype (MNHN-B 24724); G, Eodromia denticulata McLay, 1993, Kai Islands, KARUBAR, 4.9 × 4.5 (MNHN-B 26327); H-K, pattern with coxa not modified but prolonging into mobile penial tube; H-J, Dromiinae de Haan, 1833 n. status (Dromiidae); H, Moreiradromia antillensis (Stimpson, 1858) n. comb., French Guiana, stn 33, 18 × 18 mm (MNHN-B 22030); I, “Dromia” wilsoni (Fulton & Grant, 1902), Guézé coll., 22 × 37 mm (MNHN-B 26254); J, Lauridromia dehaani (Rathbun, 1923), Gulf of Suez, Monod det. Dromia dormia, 42 × 45 mm (MNHN-B 21998); K, Hypoconchinae n. subfam. (Dromiidae), Hypoconcha californiensis Bouvier, 1898, Gulf of California, 20.3 × 19.4 mm,syntype (MNHN- B 22066). Corneous regions stippled.Scale bars:A,D-F,H-K,1 mm; B, C, G, 0.5 mm.

FIG. 19. — A, B, Hypoconcha californiensis Bouvier, 1898, Gulf of California, San José Island (MNHN-B 22066); A, 17 × 18 mm, syntype, thoracic sternum, two front views; note sternites 7 and 8 strongly tilted and perpendicular to preceding ones; B, 20.3 × 19.4 mm, syntype, ventral view of abdomen, with asymmetrical, uniramous vestigial pleopods and uropods showing as ventral plates; C, H. panamensis Smith, 1869, Lower California, Bouvier det. H. digueti Bouvier, 1898, Diguet coll., about 32 mm width (MNHN-B 22071), abdomen, ventral view; note uropods showing as setiferous ventral lobes. Abbreviations: a3-a6, abdominal segments 3-6; cx1-cx5, coxae of P1-P5; e4, e5, episternites 4, 5; mxp3, external maxilliped; o, female gonopore; pl, female pleopod (setae incompletely figured); s, aperture of spermatheca; t, telson; u, uropod; v3-v5, vestigial pleopods 3-5; 3-8, sternites 3-8; 4/5-7/8, thoracic sternal sutures 4/5-7/8. Dotted line indicates difference in level. Scale bars: A, C, 2.5 mm; B, 1mm.

FIG. 3. — A, Conchoecetes artificiosus (Fabricius, 1798), Madagascar, Nosy-Bé, 23 × 22 mm (MNHN-B 6890), thoracic sternum, two front views, and spermathecae; B, C, Conchoecetes intermedius Lewinsohn, 1984; B, Madagascar, 16 × 17 mm, holotype (MNHN-B 6891), thoracic sternum with abdomen; C, Moluccas, 9 × 9 mm (MNHN-B 15890), abdomen, ventral view; note absence of vestigial pleopods. Abbreviations: a3-a6, abdominal segments 3-6; cx1-cx5, coxae of P1-P5; e4, e5, episternites 4, 5; mxp3, external maxilliped (coxae separated for clarity); n, notch on margin of abdominal segment 5; o, female gonopore; pr, holding prominence; s, aperture of spermatheca; sp, sperm plug; t, telson; u, uropod; 1-2, sternites 1-2 (normally covered by mxp3 coxae, closely approximated); 3-8, sternites 3-8; 4/5-7/8, thoracic sternal sutures 4/5-7/8. Dotted line indicates difference in level. Scale bars: 1 mm.

FIG. 25. — Frodromia atypica (Sakai, 1936), New Caledonia, MUSORSTOM 4, CP 171, 10.6 × 9.5 mm (MNHN-B 22559); A, B, thoracic sternum, with and without abdomen; C, abdomen, ventral view; note uropods showing as intercalary dorsal plates and elongated uniramous vestigial pleopods on segments 3-5; D, P5 coxa, modified and elongated into process enclosing penis and not forming penial tube. Abbreviations: a3-a6, abdominal segments 3-6; cx1-cx5, coxae of P1-P5; e, elongation of P5 coxa enclosing penis; e4, e5, episternites 4, 5; mxp3, external maxilliped; pr, holding prominence on P1 and P2; t, telson; u, uropod; v3-v5, vestigial pleopods 3-5; 1-3, sternites 1-3; 4-8, sternites 4-8; 4/5-7/8, thoracic sternal sutures 4/5-7/8. Dotted line indicates difference in level. Scale bars: 1 mm.

FIG. 15. — Platydromia spongiosa (Stimpson, 1858) n. comb.; A, B, Saint-Paul Island, Brocchi det. Platydromia depressa Brocchi, 1877, Vélain coll., 178-1875, 11 × 14 mm (MNHN-B 12724); A, thoracic sternum, two front views, note sternite 4 medially hollowed; B, dorsal view of abdomen; C, Amsterdam Island, Ams-A4, 11.II.1971, Beurois coll., 13 × 16 mm (MNHN-B 12728), ventral view of abdomen, note uropods not visible dorsally and oriented forward, and the vestigial pleopods showing only as papillae on segments 3-4. Abbreviations: a2-a6, abdominal segments 2-6; cx1-cx5, coxae of P1-P5; e4, e5, episternites 4, 5; mxp3, external maxilliped; pt, penial tube; t, telson; u, uropod; v3-v5, vestigial pleopods 3-5; 1-2, sternites 1-2; 3-8, sternites 3-8; 4/5-7/8, thoracic sternal sutures 4/5-7/8. Dotted line indicates difference in level. Scale bars: 1 mm.