Microgoneplax pelecis, Castro, 2007

Castro, Peter, 2007, A reappraisal of the family Goneplacidae MacLeay, 1838 (Crustacea, Decapoda, Brachyura) and revision of the subfamily Goneplacinae, with the description of 10 new genera and 18 new species, Zoosystema 29 (4), pp. 609-774 : 730

Microgoneplax pelecis n. sp.

( Fig. 44 )

TYPE MATERIAL. — KARUBAR, stn DW 29, ♂ holotype, cl 3.9 mm, cw 6.7 mm ( MNHN-B 30065), ♂ paratype, cl 3.5 mm, cw 5.8 mm ( MNHN-B 30066).

TYPE LOCALITY. — Indonesia, Kai Is, 05°36’S, 132°56’E, 181- 184 m.

MATERIAL EXAMINED. — Indonesia. Kai Is , KARUBAR, stn DW 29, 05°36’S, 132°56’E, 181-184 m, 26.X.1991, ♂ holotype ( MNHN-B 30065 ) ; ♂ paratype ( MNHN-B 30066 ) .

ETYMOLOGY. — From pelekys, noun in apposition, Greek for “ax” or “hatchet”, in reference to the hatchet-like G1 diagnostic of the species.

DISTRIBUTION. — Known only from Indonesia (Kai Is). Depth: 181- 184 m.

DESCRIPTION

Carapace ( Fig. 44A ) transversely rectangular, much wider than long (1.7 as wide as long in holotype). Carapace convex, without clear indication of regions. Front slightly convex, nearly straight.Notch between front, inner edge of supraorbital border. Supraorbital borders broad, conspicuously sinuous, finely granular, with long simple setae. Suborbital borders conspicuously sinuous, granular, each with large, wide, rectangular inner tooth not visible dorsally. Long, slender, acute tooth on outer orbital angle. Lateral borders beyond outer orbital teeth slightly curved, no anterolateral teeth.

Subhepatic, pterygostomial regions, with low, round tubercles.

Eye peduncles ( Fig. 44A ) long (0.8 front width), cornea elongated, spherical distal margin, not reniform.

Chelipeds (P1) unequal in holotype, only specimen having both chelipeds; fingers slender, dactylus curved in male holotype, slightly shorter than propodus (heavier chela of male holotype much shorter than propodus), with blunt teeth; dark colour on median portion of pollex of cheliped (second cheliped being regenerated) of paratype male; inner (ventral) margin of propodus with round tubercles in holotype, lower tubercles in paratype. Broad tooth on inner (ventral), proximal margin of carpus; outer (dorsal) margin of merus with low, tooth-like tubercles (larger in male holotype), long simple setae. Ambulatory legs (P2-P5) long, slender, unarmed, varying number of long simple setae; dactyli long, slender, each with 2 carinae along each side.

Male abdomen narrowly triangular, with 6 freelymovable somites plus telson; telson longer than wide. Somite 3 covers most space between P5 coxae; somite 2 only slightly narrower than somite 3, leaving large portion of thoracic sternite 8 visible. G1 ( Fig. 44B ) long, slender, wide basal part; outwardly bent, broadened distal part with large denticles along borders, pointed tip. G2 ( Fig. 44C ) slender, short, less than half G1 length; slightly curved, thick flagellum about same length of proximal part (peduncle), much expanded, flattened tip with terminal spinule.

Female unknown.

REMARKS

Microgoneplax pelecis n. sp. can be easily differentiated from congeners by its characteristic hatchet-like G1. The medially-placed outer orbital teeth are slightly more slender than in the other species.

Five females (one pre-adult parasitised by a bopyrid, three mature, one ovigerous; MNHN-B 29212) collected from station DW 29 of KARUBAR Expedition to the Kai Is could not be reliably identified since males of M. pelecis n. sp. as well as males of five species of Singhaplax were also collected from the same station. Males of species of these two genera can be differentiated because of their G1 and G2. The identification of females, on the other hand, is a difficult task. The vulvae of the four mature females of station DW 29 were all round, without a vulvar cover, and without the displaced suture 5/6 that has been identified in one mature female collected together with the males of S. styrax n. sp. (see above). The inner suborbital tooth was conspicuous (but blunt, not rectangular), which suggests their possible but highly questionable identification as M. pelecis n. sp.

Figures

FIG. 44. — Microgoneplax pelecis n. sp.,♂ holotype,cl 3.9 mm,cw 6.7 mm,Kai Is, Indonesia,KARUBAR,stn DW 29 (MNHN-B 30065): A, dorsal surface of the carapace; B, left G1, ventral view; C, left G2, ventral view. Scale bars: A, 5 mm; B, C, 1 mm.