Munida lailai, Cabezas & Macpherson & Machordom, 2009

Cabezas, Patricia, Macpherson, Enrique & Machordom, Annie, 2009, Morphological and molecular description of new species of squat lobster (Crustacea: Decapoda: Galatheidae) from the Solomon and Fiji Islands (South-West Pacific), Zoological Journal of the Linnean Society 156 (3), pp. 465-493 : 471-474

MUNIDA LAILAI SP. NOV. ( FIG. 3 )

Munida parca Macpherson, 2004: 271 .

Material examined: Fiji Islands. MUSORSTOM 10. Stn 1348, 17°30.29′S, 178°39.63′E, 11 August 1998, 353– 390 m: 1 M, 5.9 mm (holotype, MNHN-Ga6506) .

BORDAU 1. Stn 1450, 16°44.45′S, 179°58.50′E, 4 March 1999, 327– 420 m: 1 F, 4.6 mm (paratype, MNHN-Ga6507).

Etymology: The name lailai means small in the Fijian language. The name may be considered as a noun in apposition.

Description: Carapace 1.2 times longer than wide. Transverse ridges usually interrupted in cardiac and branchial regions by very short, non-iridescent setae, and some scattered long iridescent setae. Intestinal region without scales. Dorsal surface of carapace armed with ten epigastric spines; one small postcervical spine on each side. Frontal margins slightly oblique. Lateral margins subparallel. Anterolateral spine well-developed, situated at anterolateral angle, clearly not reaching the level of the sinus between the rostrum and the supraocular spines. Second marginal spine before cervical groove small, about 0.25 times the length of the anterolateral spine. Branchial margins with five small spines. Rostrum spiniform, nearly 0.4 times the length of the remaining carapace, horizontal, carinated dorsally, and slightly convex. Supraocular spines short, not reaching midlength of rostrum, and clearly falling short of end of corneae, subparallel, slightly directed upwards ( Fig. 3A ).

Fourth thoracic sternite smooth, with a few short striae. Anterior section of fourth sternite narrower than third; median margin of third sternite contiguous with fourth sternite ( Fig. 3B ).

Second abdominal somite with eight spines along anterior ridge. Second and third somites each with one transverse stria.

Epistome crest without hump near mouth opening.

Eyes large: maximum corneal diameter 0.4 times the distance between the bases of the anterolateral spines.

Basal segment of antennule (distal spines excluded) about 0.4 times the carapace length, elongate, nearly three times longer than wide (excluding spines), overreaching end of corneae, with two distal spines, and with mesial spine clearly shorter than lateral spine; two spines on lateral margin, proximal one short, located at midlength of segment, distal one long, not reaching end of segment (excluding spines) ( Fig. 3C ). First segment of antennal peduncle with one short distomesial spine nearly reaching end of second segment; second segment with two distal spines, mesial spine slightly longer than lateral spine, not exceeding end of third segment; third segment unarmed ( Fig. 3C ).

With Mxp 3 ischium about 1.5 times the length of the merus, measured along the dorsal margin, and distoventrally bearing a spine. Merus of Mxp 3 with two well-developed spines on flexor margin, distal spine smaller; extensor margin unarmed ( Fig. 3D ).

With P1s subequal in length, about 4.5 times the carapace length, squamous, with numerous uniramous iridescent setae and plumose noniridescent setae, denser on mesial and lateral borders of articles. Merus longer than carapace length, 1.5 times the carpus length, armed with some spines, with strongest spine on distal border, not reaching proximal fourth of carpus. Carpus four times as long as high, shorter than hand, several strong spines on mesial border, and some small spines on dorsal side. Palm 1.3 times longer than fingers, with row of mesial spines; some scattered small spines on dorsal side, and one row of lateral spines continuing onto fixed finger, and reaching tip. Movable finger unarmed, except proximal and distal spines. Fingers distally curving and crossing, ending in a sharp point, cutting edges slightly gaping in holotype (more straight in paratype), with small teeth of various sizes ( Fig. 3E ).

With P2 about three times the carapace length, with numerous uniramous iridescent setae and plumose non-iridescent setae along dorsal margins of articles; merus 1.3 times as long as carapace, about ten times as long as high, more than four times the carpus length, and 1.8 times as long as the propodus; propodus about nine times as long as high, and 1.3 times longer than dactylus ( Fig. 3F ). Dorsal border of merus with row of spines, increasing in size distally; ventral margin with row of spines, increasing in size distally. Carpus with distodorsal and distoventral spines; distal margin reaching the level of the merocarpal articulation of P1. Propodus with ten or 11 movable ventral spinules. Dactylus slightly curving distally, with seven movable spinules along ventral margin, and with distal third unarmed ( Fig. 3G ). P3 as long as P2; spination of P3 is similar to that of P2 ( Fig. 3H ). P4 length 0.8 times P2 length; merus 0.6 times the length of that of P2; spines along margins of merus and carpus less spinose than those of P2 and P3 ( Fig. 3I ); merocarpal articulation ending at the level of the anterolateral spine of the carapace.

Remarks: The new species is closely related to M. parca from New Caledonia ( Macpherson, 1996) and M. caeli sp. nov. from the Solomon Islands (see above). The three species have five spines on the lateral margin of the carapace behind the cervical groove, eyes moderately large, the second abdominal segment with spines, the lateral portions of the posterior thoracic sternites without granules, rostrum spiniform, the epistome crest without a hump near the mouth opening, the distomesial spine of the basal antennular segment clearly shorter than the distolateral spine, and with the distomesial spine of the basal antennal article nearly reaching the end of the third article. Munida lailai sp. nov. can be distinguished from M. parca according to the following characters.

1. The chelipeds (P1) are clearly longer in the new species than in M. parca . In the new species, the length of P1 is about 4.5 times the carapace length, whereas this ratio is about 2.5 times in M. parca . The carpus is nearly 2.5 times longer than broad in M. parca , whereas it is four times longer than broad in the new species.

2. The walking legs (P2–P4) are longer in M. parca . P2 is about three times the carapace length in the new species, being slightly more than two times in M. parca . Furthermore, the merus of this leg is nearly as long as the carapace in M. parca , being longer in M. lailai sp. nov. In addition, the merocarpal articulation ends at the level of the anterolateral spine of the carapace in the new species, whereas in M. parca this articulation slightly exceeds the level of the anterior branch of the cervical groove.

On the other hand, M. lailai sp. nov. can be easily distinguished from M. caeli sp. nov. by the following aspects.

1. The antennular peduncle is clearly longer in M. lailai sp. nov. than in M. caeli sp. nov. The basal article clearly overreaches the corneae in M. lailai sp. nov., whereas this article only ends or slightly exceeds the corneae in M. caeli sp. nov.

2. The walking legs (P2–P4) are longer in M. lailai sp. nov. P2 is about three times the carapace length in M. lailai sp. nov., being twice the carapace length in M. caeli sp. nov.

Distribution: Fiji Islands, at a depth of between 327 and 420 m.

Figures

Figure 3. Munida lailai sp. nov., male holotype, 5.9 mm, (MNHN-Ga6506). Fiji Islands. A, carapace and abdomen, dorsal view. B, sternum. C, left antennule and antenna, ventral view. D, ischium and merus of right third maxilliped, lateral view. E, right cheliped, lateral view. F, left P2, lateral view. G, dactylus, left P2, lateral view. H, right P3, lateral view. I, right P4, lateral view. Scale: A, E, F, H, I = 2 mm; B, C, D, G = 1 mm.