Munida pectinata, Macpherson & Machordom, 2005

Macpherson, E. & Machordom, A., 2005, Use of morphological and molecular data to identify three new sibling species of the genus Munida Leach, 1820 (Crustacea, Decapoda, Galatheidae) from New Caledonia, Journal of Natural History 39 (11), pp. 819-834 : 828-831

Munida pectinata sp. nov.

( Figure 3 )

Material examined

New Caledonia. NORFOLK 1, stn 1681, 22 June 2001, 24 ° 43.835 9 S, 168 ° 09.699 9 E, 228–240 m: one ovigerous female 9.1 mm; stn 1727, 27 June 2001, 23 ° 17.377 9 S, 168 ° 14.346 9 E, 190–212 m: two males 7.6–7.9 mm; four ovigerous females 6.4–10.0 mm (holotype, ovigerous female 6.9 mm, MNHN-Ga 4618); three females 6.0– 6.9 mm .

NORFOLK 2, stn 2096, 29 October 2003, 24 ° 43.91 9 S, 168 ° 08.88 9 E, 230–240 m: two males 7.1–11.2 mm, three ovigerous females 10.4–11.1 mm, one female 7.9 mm.

Etymology

From the Latin, pecten, comb, in reference to the spinulation of the merus of the third maxilliped.

Description

Carapace longer than wide. Transverse ridges mostly interrupted, with dense, very short, non-iridescent setae, and few long non-iridescent setae. Main transverse striae on gastric area interrupted. Few scales and secondary striae between main striae. Scales on intestinal region absent. Gastric region with 8–10 epigastric spines. One parahepatic, one anterobranchial (sometimes absent) and one postcervical spine on each side. Frontal margins transverse. Lateral margins slightly convex. Anterolateral spine well developed, at anterolateral angle, not reaching level of sinus between rostrum and supraocular spines; two marginal spines before cervical groove, anterior one three times shorter than anterolateral spine. Branchial margins with five spines. Rostrum two-thirds as long as remaining carapace, horizontal, tip slightly upwards directed. Supraocular spines well developed, reaching midlength of rostrum, and not exceeding end of corneae ( Figure 3A ).

Thoracic sternites smooth, without striae, granules or carinae. Anterior part of fourth sternite slightly wider than third ( Figure 3B ).

Second abdominal somite unarmed. Second and third somites each with three transverse striae.

Eyes moderately large, maximum corneal diameter about one-third distance between bases of anterolateral spines.

Basal segment of antennule (distal spines excluded), about one-quarter carapace length, slightly over-reaching corneae, with two distal spines, mesial spine longer than lateral spine; two spines on lateral margin, proximal one short, located at midlength of segment, distal one long, over-reaching distolateral spine ( Figure 3C ).

First segment of antennal peduncle with one long distal spine on mesial margin, reaching end of third segment and not reaching base of long lateral spine of basal segment of antennule; second segment with two long distal spines, mesial spine clearly over-reaching end of antennal peduncle; penultimate segment unarmed ( Figure 3C ).

Ischium of third maxilliped about 1.8 times length of merus measured along dorsal margin, distoventrally bearing spine. Merus of third maxilliped with three well-developed spines on flexor margin, distal smaller, extensor margin with small distal spine ( Figure 3D ).

Chelipeds squamous, with some iridescent uniramous setae, denser on mesial borders of articles. Palm as long as fingers. Merus armed with some spines, strongest spine on distal border short, reaching proximal quarter of carpus. Carpus with several spines on dorsal side and several spines scattered on mesial side. Palm with several spines scattered on mesial and dorsal sides, spines along lateral border continuing along fixed finger, some spines on proximal half of movable finger. Fingers distally curving and crossing, ending in a sharp point ( Figure 3E ).

Second pereiopod about 2.5 carapace length; merus shorter than carapace, about six times as long as high, about 1.3 times as long as propodus; propodus 6.5 times as long as high, about 1.5 times dactylus length ( Figure 3F ). Merus with small spines on dorsal border, increasing in size distally, ventral margin with one long distal spine. Carpus with few dorsal spines and one distoventral spine. Propodus with 10–11 movable ventral spines. Dactylus slightly curving distally, with eight to nine movable spinules along entire ventral margin ( Figure 3G ). Third pereiopod similar to second; fourth pereiopod shorter than second and third. Merus of fourth pereiopod two-thirds length of second pereiopod. Epipods absent from all pereiopods.

Remarks

Munida pectinata belongs to the group of species closely related to M. clinata Macpherson, 1994 , and has the following features: five spines on the lateral margins of the carapace behind the cervical groove, oblique frontal margins, smooth thoracic sternites, unarmed abdominal somites, spiniform rostrum, and distal spine on the extensor margin of the merus of the third maxilliped.

However, these two species are distinguished by several constant morphological characters as follows.

The frontal margins of the carapace are more oblique in M. clinata than in M. pectinata .

The distomesial spine of the basal antennular segment is longer than the distolateral spine in M. pectinata , whereas in M. clinata these spines are subequal.

The distomesial spine of the basal segment of the antennal segment clearly over-reaches third segment in M. pectinata . In M. clinata this spine reaches only the end of the second segment.

The molecular data indicated a close similarity of M. pectinata to M. clinata and M. notata . Thirty-three substitutions were found between the M. pectinata specimens and M. clinata , and 37 with M. notata , for 16S. For COI, M. pectinata specimens have two distinct haplotypes (only one transition change between them), which showed 63–66 diagnostic positions for M. clinata and 67–68 for M. notata . However, the molecular phylogenetic analyses always consistently showed M. pectinata as a sister taxon of M. clinata . For the global data, the divergence with respect to M. clinata ranged from 7.68% to 7.85% (5.2% for 16S and from 9.6% to 10% for COI; Table II).

Distribution

New Caledonia, between 190 and 240 m.

Figures

Figure 3. Munida pectinata sp. nov., ovigerous female 6.9 mm, holotype from stn 1727 (NORFOLK 1). (A) Carapace, dorsal view; (B) sternal plastron; (C) ventral view of cephalic region, showing antennular and antennal peduncles; (D) right third maxilliped, lateral view; (E) right cheliped, dorsal view; (F) right first walking leg, lateral view; (G) dactylus of right first walking leg, lateral view.