Mclaydromia colini, 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 : 80-82

Mclaydromia colini n. sp.

( Figs 12 ; 13 )

Dromidiopsis dubia – McLay 1993: 138, fig. 15c. (Non Dromidiopsis dubia Lewinsohn, 1984 ).

TYPE MATERIAL. — New Caledonia. LAGON, stn 619, 22°3.2’S, 166°54.2’E, 27-42 m, 06.VIII.1986, holotype 16.2 × 13.2 mm ( MNHN-B 22546 ) ; stn 111, 22°24.30’S, 166°47.70’E, 25 m, 22.VIII.1984, paratype 10.4 × 9.1 mm ( MNHN-B 26282 ) ; stn 569, 22°48.80’S, 166°58.90’E, 62 m, 17.VII.1985, paratype ovigerous 9.4 × 8.6 mm ( MNHN-B 26289 ) ; stn 215, 21°52.90’S, 165°49.90’E, 14 m, 21.IX.1984, paratype ovigerous 12.0 × 10.3 mm ( MNHN-B 26284 ) ; stn 303, 22°38’S, 166°49.10’E, 30-35 m, 27.XI.1984, paratype 11.3 × 9.7 mm ( MNHN-B26280 ) ; stn 104, 22°26’S, 166°40.40’E, 24 m, 22.VIII.1984, paratype ovigerous 9.6 × 8.5 mm ( MNHN-B 26281 ) .

Although we have examined all the material from New Caledonia referred by McLay (1993), only the specimens selected for the type series are given herein. For the locality details of remaining specimens see McLay (1993:138). ETYMOLOGY. — The present species is dedicated to Colin L. McLay (University of Canterbury, Christchurch, New Zealand).

TYPE LOCALITY. — New Caledonia, 22°3.2’S, 166°54.2’E, 27- 42 m.

DISTRIBUTION. — Only known from New Caledonia.

DESCRIPTION

Carapace noticeably longer than wide, covered with a fine tomentum. Tomentum more developed on flanks of carapace, chelipeds, and legs. Cardiac region ill defined; branchial groove well recognizable, a blunt small tooth just behind; regions of carapace not defined. Front wide. Median frontal tooth (rostrum) small but well recognizable. Lateral frontal teeth (pseudorostral) prominent, blunt, so that entire front is produced forward. Supraorbital tooth quitely distinct. Exorbital angle without tooth. Orbital fissure very deep. Suborbital margin abruptly interrupt- ed, forming suborbital lobe, and leaving deep and broad hiatus between suborbital lobe and antenna. Two marked but blunt teeth on anterior half of anterolateral margin: first tooth lying about level of orbital fissure; second tooth much larger and placed at higher level than first; a smaller, rounded third anterolateral tooth visible. Subhepatic tubercle strong in adults, low but well recognizable in young.

Carpus of cheliped ornamented with several tubercles on dorsal surface and with strong tubercle on external distal margin; remaining cheliped articles smooth. Cutting edge of dactylus with minute proximal teeth followed by molariform tooth backwards directed, opposed to similar tooth on cutting edge of fixed finger; distally, the usual interlocking teeth. Cheliped with welldeveloped epipodite.

Rather dense tomentum covering P2 to P5, their margins fringed with closely placed plumose setae. P2 and P3 robust. Upper margin of merus with a rounded tubercle placed distally; upper surface of remaining articles smooth, no obvious tubercles or conspicuous elevations. Dactylus slightly shorter than propodus, inner margin armed with acute spines, claw strong; condyles of P2 and P3 very strong, rounded. P5 longer than P4. Dactylus of P4 curved, opposed by small propodal spine; no spine on outer propodal margin. Dactylus of P5 strongly curved, opposed by single spine propodal, stronger than on P4; a minute spine on distal outer propodal margin.

Abdomen composed of six free segments, plus telson. Male telson about as long as broad, rounded distally. Abdominal segment 2 with wing-like lateral expansion covering base of penial tube issued from P5 coxa. Abdominal segment 6 abruptly constricted, considerably narrower than segment 5. Uropod plates salient, visible dorsally. Abdominal holding consisting of uropod plate fitting in front of curved serrate flange on base of P2 coxa; additionally, on P1 coxa a marked tubercle, may be a group of very small and closely approximated granules, without contact with telson.

REMARKS

Dromidiopsis dubia was described from a single male (the holotype) from Madagascar. The comparison of the holotype and two additional adult males from Madagascar with several individuals from New Caledonia, previously identified as D. dubia by McLay (1993: 138), has shown that the New Caledonian specimens should no longer be attributed to D. dubia . The material belongs to a new species, named herein Mclaydromia colini n. gen., n. sp.

In addition to male holotype (10.5 × 9 mm) of D. dubia Lewinsohn, 1984 , the following material has been examined:

Madagascar. Near Tany Kely, 13°27’S, 48°10’E, 30 m, 13.VIII.1971, A. Crosnier coll., holotype 10.5 × 9 mm ( MNHN-B 6894). — Near Nosy-Bé, Tany Kely, north-west coast, 23 m, 30.IX.1970, P. Laboute coll., 12.5 × 11.5 mm ( MNHN-B 22592). — 13°40.3’S, 47°48’E, 32 m, 05.XII.1972, A. Crosnier coll., 15 × 13 mm ( MNHN-B 22593).

Mclaydromia colini n. gen., n. sp. and M. dubia n. comb. can be differentiated as follows: 1) in M. colini n. gen., n. sp. the blunt lateral frontal teeth (pseudorostral teeth) are prominent, so that entire front is produced forward, while in M. dubia n. comb. the lateral frontal teeth are short and rounded so that entire front is produced only slightly forward; and 2) in M. colini n. gen., n. sp. the dorsal face of carpus of cheliped is ornamented with conspicuous tubercles, whereas in M. dubia n. comb. the dorsal surface of carpus is smooth.

The above characters are constant throughout the material examined, regardless sex and age of the individuals examined. Full-grown individuals of Mclaydromia colini n. gen., n. sp. and M. dubia n. comb. can also be separated by the following additional characters: 1) in Mclaydromia colini n. gen., n. sp. suborbital margin abruptly interrupted, forming well individualized suborbital lobe and leaving deep and broad hiatus between suborbital lobe and antenna (suborbital margin gently interrupted, leaving only a narrow sinus between suborbital lobe and antenna in M. dubia n. comb.); 2) in M. colini n. gen., n. sp. a small, rounded but well visible third anterolateral tooth (only a small elevation behind second anterolateral tooth of carapace in M. dubia n. comb.); and 3) in M. colini n. gen., n. sp. subhepatic tubercle strong (very low in M. dubia n. comb.).

The original description of Dromidiopsis dubia mentions the absence of subhepatic tubercle on carapace and the smooth cheliped, except two weakly developed tubercles on distal margin of carpus ( Lewinsohn 1984: 102). We confirm these features in male holotype (10.5 × 9 mm) but, in a larger male (15 × 13 mm), a subhepatic tubercle is well recognizable although being very low, and the two teeth on carpus of cheliped are absent. The development of carapace teeth varies with age in both species. A colour photograph of a specimen from Maldive Islands is given by Debelius (1999: 249, as D. dubia ).

Two individuals of M. colini n. gen., n. sp. were carrying a sponge cap.

Figures

FIG. 12. — Mclaydromia colini n. gen., n. sp.; A, LAGON, stn 111, 25 m, 10.4 × 9.1 mm, paratype (MNHN-B 26282), thoracic sternum with abdomen; B, LAGON, stn 569, 62 m, ovigerous 9.4 × 8.6 mm, paratype (MNHN-B 26289), thoracic sternum and spermathecae. Abbreviations: a6, abdominal segment 6; cx1-cx4, coxae of P1-P4; e4, episternite 4 (very small); mxp3, external maxilliped (coxae separated for clarity); o, female gonopore; pr, holding prominence; s, aperture of spermatheca; t, telson; u, uropod; 1-2 sternites 1-2 (normally not exposed); 3, sternite 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. 13. — Mclaydromia colini n. gen., n. sp., LAGON, stn 111, 25 m, 10.4 × 9.1 mm, paratype (MNHN-B 26282), views of frontal border of carapace; A, dorsal view; B, anterodorsal view. Scale bar: 2.5 mm.