Lewindromia, 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 : 74-78

Genus Lewindromia n. gen.

( Fig. 11 )

Dromia – Rüppell 1830 pro parte: 16. — H. Milne Edwards 1837 pro parte: 170. — Alcock 1900 pro parte: 139. (Non Dromia Weber, 1795 ).

Dromidia – Borradaile 1903a pro parte: 299. — Ihle 1913 pro parte: 31. — Edmondson 1922: 34. — Barnard 1950 pro parte: 319, 323. — Garth 1973: 316. — Lewinsohn 1977: 9; 1979 pro parte: 2. — Tirmizi & Kazmi 1991 pro parte:27. (Non Dromidia Stimpson, 1858 ).

Cryptodromiopsis – McLay 1993 pro parte: 187, 192; 2001a pro parte: 84. — McLay et al. 2001 pro parte: 740, table 3. — Chen & Haibao 2002 pro parte: 102, 541, 542. (Non Cryptodromiopsi s Borradaile, 1903).

TYPE SPECIES. — Cryptodromiopsis unidentata Rüppell, 1830 by present designation. Gender: feminine.

ETYMOLOGY. — The genus Lewindromia n. gen. is dedicated to Chanan Lewinsohn (1927-1983) in recognition for his contribution to the knowledge of the Indian Ocean dromiids.

SPECIES INCLUDED. — Cryptodromiopsis unidentata Rüppell, 1830 .

Dromidia unidentata hawaiiensis Edmondson, 1922 and Cryptodromia unilobata Campbell & Stephenson, 1970 were synonymised with Dromidia unidentata by McLay (1993: 192, 194).

DISTRIBUTION. — Indo-West Pacific: Red Sea and Indian Ocean, including sea mounts of the western Indian Ocean (see Zarenkov 1994), with a large extension in the Pacific ( Australia, Hawaii, Kermadec Islands, Easter Island, see Garth 1973: 316).

DESCRIPTION

Carapace longer than wide, evenly convex; dorsal surface with regions poorly defined; branchial groove marked, deeply notching external border. Anterolateral margin not joining exorbital angle, long, convex, entire, only with a very blunt tooth behind level of branchial groove; posterolateral margins not noticeably convergent posteriorly. Front narrow, with rostrum very small and blunt, not visible dorsally, and two pseudorostral teeth; supraorbital, suborbital and exorbital teeth present. Antenna: urinal article noticeably developed and rather straight; basal article thick, with exopod strongly developed and internal corner slightly produced, much shorter than exopod; article 4 wide. Mxp3: coxae closely approximated. Thoracic sternite 3 not visible. Sternite 4 very narrow, forming acute plate, ending in sharp tip in both sexes. In females, sternites 7 and 8 tilted, almost perpendicular in relation to precedent ones. Female sternal sutures 7/8 posteriorly wide apart, sharply close to each other at level of P3 where they are marked by thick ridge; apertures of spermathecae ending together on slight prominence between P2 ( Fig. 11C ). No sternal parts (very small episternite 4 may be discernible) remaining visible when male abdomen applied against ventral surface.

Male abdomen very long, without pleural parts, reaching mxp3, completely covering narrow and deep sterno-abdominal depression, and with all segments free; telson very long, with large base and regularly tapering, pointed at tip. Telson of females semi-ovate. Male segment 6 with external borders oblique and modified on edges. No vestigial pleopods in males. Uropods as dorsal plates, vertically oriented in males ( Fig. 11B ), welldeveloped in females. Uropods involved in holding of abdomen. A very efficient abdominal holding provided by long and prominent serrulated carina on P2 coxa; presence of large blunt prominence on P1 coxa.

Chelipeds without epipod. P1, P2 and P3 not knobbed nor nodose; propodus of P2 and P3 without distal spine; inner margin of dactylus armed with spines. P4 and P5 reduced, P5 being much longer than P4 and, when extended forward, reaching about mid-length of anterior margin of carapace. P5 coxa very developed in both sexes. Propodus of P4 and P5 very short and thick, as wide as long, with one distal spine opposing dactylus which is not markedly curved and ends in long horny spine; two smaller outer propodal spines.

Male P5 coxa with mobile penial tube.

Male G2 much longer than G1, thin and long flagellum overreaching sterno-abdominal depression.

Carrying behaviour

Individuals carry a wide range of camouflage material (sponges, soft coral, compound or solitary ascidians, actinians), and the cap is often very large, so that the crab is “deeply embedded” ( McLay 2001a: 84). Lewindromia unidentata n. comb. looks like “a hairy ball that fits tightly into its piece of camouflage” ( McLay 2001a: 84). See also Chen & Haibao 2002: pl. 5, fig. 2.

REMARKS

Dromia unidentata was transferred to Dromidia by Kossmann (1880: 67) until McLay (1993: 192) placed it in Cryptodromiopsis . The study of Dromidia sensu nobis and Cryptodromiopsis sensu nobis, which are restricted to their type species, led us to conclude that D. unidentata does not belong to neither of these genera and that a new genus should be erected for it. That new genus is named herein Lewindromia n. gen.

We found it useful to compare Lewindromia n. gen. with the genera below; special reference is made to the features other than those of the carapace.

Lewindromia n. gen. is distinguished from Austrodromidia sensu nobis ( Figs 1 ; 2 ) by the following characters: 1) uropods showing as dorsal plates, vertically oriented (markedly reduced or even obsolete ventral plates in Austrodromidia ); 2) male segment 6 with external borders oblique (external borders anteriorly hollowed and posteriorly expanded in Austrodromidia ); and 3) spermathecae ending together on central prominence between P2 (ending wide apart between P 2 in Austrodromidia ).

The differences between Lewindromia n. gen. and Cryptodromia (type species: C. coronata Stimpson, 1858: 226 , by original designation) include: 1) apertures of spermathecae closely approximated (situated wide apart in Cryptodromia ; see the diagnosis by Stimpson 1858: 225: “ Foeminae sterni sulci remoti, ad segmentum pedum secundi paris tantum producti, terminis in tuberculis ”); 2) male telson much longer than wide (wider than long in Cryptodromia ); 3) male thoracic sternite 3 not visible (visible dorsally in Cryptodromia ); 4) male thoracic sternite 4 ending in acute tip (sternite 4 anteriorly truncated in Cryptodromia ).

Differences between Lewindromia n. gen. and Cryptodromiopsis sensu nobis ( Fig. 4 ) include: 1) thoracic sternite 1-3 concealed in males (exposed in Cryptodromiopsis ); 2) coxae of mxp3 placed close together (separated by distinct gap in Cryptodromiopsis ); 3) thoracic sternite 4 ending in acute tip in males (sternite 4 not pointed in Cryptodromiopsis ); 4) male telson much longer than wide (wider than long in Cryptodromiopsis ); and 5) apertures of spermathecae at level of P2 (at level of P 1 in Cryptodromiopsis ).

Lewindromia n. gen. is distinguished from Dromidia sensu nobis ( Fig. 5 ) by the following characters: 1) male abdominal segment 6 with external borders oblique and sinuous (external borders subparallel in Dromidia ); 2) male telson much longer than wide, regularly tapering, and the tip becoming very narrow (telson wider than long, ending by sharp spine in Dromidia ); 3) male uropods as dorsal plates, vertically oriented, exposed and completely visible dorsally (almost totally concealed ventral plates in Dromidia ); 4) uropods involved in abdominal holding which consists of uropods fitting in front of serrulated carina on P2 coxae; an additional strong, rounded prominence on P1 coxa (uropods not involved at all in abdominal holding; a strong spine directed backwards, partly overhanging abdomen in Dromidia ); and 5) thoracic sternite 4 tapering and ending in acute tip (sternite 4 broad, ending in rounded tip in Dromidia ).

Lewindromia n. gen. and Dromidiopsis sensu nobis ( Fig. 6 ), both with uropods oriented vertically, differ from each other as follows: 1) all abdominal segments free (abdominal segments 5 and 6 fused together in Dromidiopsis ); 2) pseudorostral teeth prominent, so that entire front is strongly produced forward (lateral frontal lobes extremely low so that entire front is produced forward only slightly in Dromidiopsis ); 3) propodus of P4 and P5 subequal in size (of different size, that of P5 much longer in Dromidiopsis ); 4) when extended forward, P5 reaching about mid-length of anterior margin of carapace (P5 much long, reaching as far as outer orbital angle in Dromidiopsis ); 5) female sternal sutures 7/8 sharply close to each other at level of P3 where they are lined by thick ridge (separated wide apart, getting progressively close to each other in Dromidiopsis ); 6) apertures of spermathecae at level of P2 (at level of P1 or just behind them in Dromidiopsis ); and 7) thoracic sternite 4 ending in acute tip (sternite 4 truncated distally in Dromidiopsis ).

Lewindromia n. gen. and Homalodromia ( Fig. 9 ), both with uropods vertically oriented, differ from each other, as follows: 1) apertures of spermathecae together on slight prominence between P2 ( Fig. 11C ) (apertures at each extremity of a tubular prominence forming bridge between P1 coxae in Homalodromia ); 2) sternite 4 forming acute plate, ending in sharp tip ( Fig. 11A, C ) (bluntly truncate at tip in Homalodromia ); and 3) no sternal parts remaining visible when male abdomen applied against ventral surface ( Fig. 11B ); small episternite 4 hardly dicernible at lower plane or not visible (sternite 4 and episternite 4 remaining visible in Homalodromia ).

Lewindromia n. gen. and Lamarckdromia n. gen. share the thoracic sternite 4 showing as triangular acute plate, but narrower in Lewindromia n. gen. The following characters readily distinguish Lewindromia n. gen. from Lamarckdromia n. gen. ( Fig. 10 ): 1) male abdominal segment 6 with external borders oblique and sinuous (external borders subparallel in Lewindromia n. gen.); 2) male telson much longer than wide, regularly tapering, the tip becoming narrow (telson wider than long, rounded at tip, in Lewindromia n. gen.); 3) male uropods plates exposed, vertically oriented, involved in abdominal holding (showing as totally concealed ventral plates, not involved, in Lewindromia ); and 4) thoracic sternite 4 forming acute plate, ending in sharp tip (with anterior margin triangular in Lewindromia n. gen.).

Lewindromia n. gen. and Lauridromia ( McLay 1993: 145, table 2; see Guinot & Bouchard 1998, fig. 2A-C) share several characters: triangular shape of sternite 4, although narrower in Lewindromia n. gen.; male abdomen completely covering sterno-abdominal depression; vertically oriented uropods; holding prominences on P2 and P1 coxae. Lewindromia n. gen. differs from Lauridromia by: 1) all abdominal segments free (segments 5 and 6 fused, at least in some extent, in Lauridromia ); 2) apertures of spermathecae grouped together on slight prominence between P2 ( Fig. 11C ) (wide apart, at level of episternites 4, each at summit of tubercle, in Lauridromia ); 3) epipod on cheliped absent (present in Lauridromia ); and 4) terminal apparatus of P5 consisting of only one distal propodal spine opposing the dactylus, and two outer propodal spines small (two propodal spines and several others well-developed spines in Lauridromia ).

Lewindromia n. gen. differs from all the above genera by having an extremely long G2, which overreaches the tip of telson when abdomen is completely folded (G2 shorter, fitted inside sternoabdominal depression in the other genera).

Figures

FIG. 11. — Lewindromia unidentata (Rüppell, 1830) n. comb.; A, B, Obock, Lewinsohn det. Dromidia unidentata, about 30 mm width (MNHN B-6930), thoracic sternum, two front views, without abdomen and with abdomen; C, Red Sea, Aden and Obock, Nobili det. D. unidentata, 24 × 24 mm (MNHN-B 6940), thoracic sternum and spermathecae. Abbreviations: a6, abdominal segment 6; cx1-cx5, coxae of P1-P5; e4, e5, episternites 4, 5 (in fact, episternite 4 not so visible when abdomen folded); mxp3, external maxilliped; o, female gonopore; pr, holding prominence: blunt prominence on P1, carina on P2; 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. 1. — Austrodromidia australis (Rathbun, 1923), New South Wales, off Eden, Goonambee, 1922, 29.5 × 33 mm (AM P5777); A, thoracic sternum, two front views; B, abdomen, dorsal view; C, abdomen, ventral view; note uropods showing as very narrow ventral plates. Abbreviations: a6, abdominal segment 6; cx1-cx5, coxae of P1-P5; e4, e5, épisternites 4, 5; mxp3, external maxilliped; pr, holding prominence; pt, penial tube; t, telson; u, uropod; 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 bar: 5 mm.

FIG. 2. — Austrodromidia octodentata (Haswell, 1882), South Australia, Kangaroo Island, Endeavour, Rathbun det. Cryptodromia octodentata; A, B, 39 × 42 mm (AM E. 801); A, thoracic sternum, two front views; B, abdomen, ventral view; note uropods reduced to nearly obsolete buds; C, 44 × 46 mm (AM P. P2311), thoracic sternum and apertures of spermathecae, covered with spermatic plug. Abbreviations: a6, abdominal segment 6; cx1-cx5, coxae of P1-P5; e4, e5, episternites 4, 5; mxp3, external maxilliped; o, female gonopore; pr, holding prominence; pt, penial tube; sp, spermatic plug; t, telson; u, uropod; 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: 5 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. 5. — Dromidia hirsutissima (Lamarck, 1818), “Cap de Bonne-Espérance”, 26.6 × 31 mm, lectotype (MNHN-B 22034); A, thoracic sternum, two front views; B, C, abdomen, dorsal and ventral views; note uropods showing as ventral plates, hardly visible dorsally. Abbreviations: a5, a6, abdominal segments 5, 6; cx1-cx5, coxae of P1-P5; e4, e5, episternites 4, 5; pr, spiniform holding prominence; pt, penial tube; v4, v5, elongated vestigial pleopods 4 and 5 (pleopods present also on segment 3); t, telson; u, uropod; 4-6, sternites 4-6; 5/6-7/8, thoracic sternal sutures 5/6-7/8. Dotted line indicates difference in level. Scale bars: 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. 9. — A, Homalodromia coppingeri Miers, 1884, Seychelles, 5.2 × 5.3 mm (MNHN-B 26130), thoracic sternum with abdomen; B, Homalodromia? coppingeri Miers, 1894, New Caledonia, LAGON, stn 556, 7.8 × 9 mm (MNHN-B 22528), thoracic sternum and spermathecae; note apertures of spermathecae at level of P1, concealed by sperm plug, and vestigial holding prominence on P2 coxa of female. Abbreviations: a6, abdominal segment 6; b, tubular bridge between apertures of spermathecae; cx1-cx4, coxae of P1-P4; e4, episternite 4; mxp3, external maxilliped; o, female gonopore; pr, holding prominence; sp, sperm plug; t, telson; u, uropod; v, vestige of the holding prominence in the female; 4-8, sternites 4-8; 4/5-7/8, thoracic sternal sutures 4/5-7/8. Scale bar: 1 mm.

FIG. 10. — Lamarckdromia globosa (Lamarck, 1818) n. comb., New South Wales, Port Jackson, det. Dromidia excavata Stimpson, McLay redet. Dromidiopsis globosa (MNHN-B 22041); A, 25 × 25 mm, thoracic sternum and spermathecae; B-D, 24 × 25 mm, extremity of abdomen in dorsal view, abdomen in ventral view, and thoracic sternum without abdomen. Abbreviations: a3, a6, abdominal segments 3, 6; cx1-cx5, coxae of P1-P5; e4, e5, episternites 4, 5; mxp3, external maxilliped; o, female gonopore; pr, holding prominence; pt, penial tube; s, aperture of spermatheca; t, telson; u, uropod; 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: 2.5 mm.