Munida zebra Macpherson, 1994

Komai, Tomoyuki & Higashiji, Takuo, 2016, New records of the squat lobster genus Munida Leach, 1820 (Crustacea: Decapoda: Anomura: Munididae) from deep-water off Okinawa Islands, Ryukyu Islands, Japan, with description of a new species, Zootaxa 4109 (5), pp. 542-554 : 547-552

Munida zebra Macpherson, 1994

[New Japanese name: Adeyaka-chu-koshiori-ebi] ( Figs 3–5 )

Munida zebra Macpherson, 1994: 556 , figs 63, 89 (type locality: New Caledonia, 24°55’S, 168°22.0’E, 515 m).— Baba 2005: 128, 276.— Baba et al. 2008: 127.— Yaldwyn & Webber 2011: 212.

Material examined. North of Ie Island, Okinawa Islands, 26°52.659’N, 127°42.982’E, 495 m, 12 December 2007, bait trap, coll. A. Kaneko, 1 female (cl 17.5 mm), CBM-ZC 11349.

Description of Japanese specimen. Carapace (excluding rostrum) ( Fig. 3 A) 1.2 times as long as wide. Dorsal surface gently convex transversely; main transverse ridges uninterrupted medially; secondary transverse striae numerous; most ridges and striae with row of setae. Gastric region slightly elevated, with 6 pairs of epigastric spines (these spines unequal in size, second mesial longest); postrostral carina low, obsolescent. Cervical groove distinct. Parahepatic, branchial dorsal and postcervical spines present. Anterior part of branchial region between cervical groove and transverse groove with squamiform ridges; posterior part of branchial region with 13 transverse ridges (excluding posterodorsal ridge). Cardiac region with 5 main transverse ridges interspersed by secondary striae, all not interrupted medially. Intestinal region with short scale-like ridge medially; posterodorsal ridge distinct, gently convex, with 3 transverse striae irregularly interrupted. Frontal margins slightly oblique. Anterolateral margins gently convex; lateral margins slightly sinuous in general outline. Anterolateral spines each located at anterolateral angle of carapace, long, exceeding level of sinus between rostrum and supraocular spines; second marginal spine anterior to cervical groove less than half-length of anterolateral spine. Branchial margins each with 4 small spines, anteriormost spine slightly longer than other spines.

Rostrum ( Fig. 3 A) spiniform, 0.3 times as long as carapace, nearly horizontal in lateral view; dorsal margin bluntly carinate. Supraocular spines long, slightly diverging anteriorly and very slightly ascending in lateral view, 0.6 length of rostrum. Inner orbital spine bifid, curved outward, clearly visible in dorsal view.

Pterygostomial flap bluntly pointed anteriorly with minute granules ( Fig. 3 D); lateral face rugose with scattered obliquely transverse or short, scale-like ridges.

Thoracic sternite 3 ( Fig. 3 B) about 1.4 times wider than long, distinctly separated from sternite 4, slightly wider than anterior width of sternite 4; anterior margin granulate, with distinct, V-shaped median notch. Sternite 4 medially with medially interrupted, obliquely transverse striae. Sternites 5–7 smooth. Transverse ridges dividing sternites nearly smooth, with sparse short setae.

Pleomere 2 ( Fig. 3 A) with 3 transverse stria on tergum (anterior two distinct, posteriormost stria faint; anterior ridge armed with 4 pairs of spines. Pleomere 3 ( Fig. 3 A) with 2 distinct transverse striae on tergum, unarmed anteriorly. Pleomere 4 with 2 distinct transverse striae. Pleura of pleomeres 2–4 with scale-like striae. Pleomere 5 with 2 transverse striae on tergum (anterior stria interrupted laterally) and 1 transverse stria on each pleuron. Pleomere 6 ( Fig. 3 C) with 1 laterally interrupted stria anterior to midlength and broadly W-shaped groove on posterior half, otherwise smooth; posterior margin tri-lobed. Telson ( Fig. 3 C) about 1.6 times as wide as long, incompletely divided in 7 plates (division of posterolateral plate not obvious); many scale-like tubercles on posterior plates.

Eyes ( Fig. 3 A) moderately large. Cornea dilated, corneal width distinctly greater than distance between rostrum and supraocular spine and about 0.2 cl. Eyestalk with submarginal flange; eyelashes very short.

Basal article of antennular peduncle ( Fig. 3 A, D) slender, length excluding distal spines about 2.2 of width; distal spines slender, subequal; 2 lateral spines present, distal spine located distinctly proximal to base of distolateral spine, far overreaching it, proximal spine short, located at midlength of article; statocyst lobe not inflated, ventral surface rounded, with few minute tubercles and sparse setae.

Antennal peduncle ( Fig. 3 A, D) moderately stout, just reaching distal corneal margins. First article with long distomesial spine reaching distal end of third article; distolateral angle unarmed. Second article with long spine at distomesial and distolateral angles, spines subequal in length, distomesial spine slightly overreaching distal end of fourth article. Third article unarmed. Fourth article very short, unarmed.

Third maxilliped (Fig. E) relatively slender. Ischium distinctly longer than merus, with strong spine at flexor distal angle, extensor distal angle with minute denticle; lateral face with scale-like ridges medially. Merus slightly narrowed distally, flexor margin with 2 greatly unequal spines, distal spine tiny, proximal spine prominent, arising slightly proximal to midlength; extensor distal margin without spine. Exopod slender, tapering, distinctly overreaching distal margin of merus; lateral surface slightly rugose.

Chelipeds ( Figs 3 F, G; 4A, B) subequal, about 3.2 times as long as carapace. Merus with 2 rows of spines on dorsal surface, lateral row extending over entire length, with 9 spines, mesial row restricted to distal half, with 4 spines (spines in both rows increasing in size distally), dorsomesial distal spine prominent, slightly larger than dorsolateral distal spine; lateral face with numerous small scale-like tubercles and with 1 small subterminal spine adjacent to ventrodistal angle; mesial face with scattered small granules, armature including 2 rows of spines increasing in size distally (dorsal row with 3 small spines, ventral row with 5 spines); ventral surface with scattered scale-like tubercles. Carpus 0.9 times as long as palm, 2.8 times longer than distal width; dorsolateral margin with row of 5 or 6 small, subequal spines, dorsomesial margin with double row of 7 unequal spines; lateral and ventral surfaces with scattered small, scale-like tubercles, ventrodistal angle produced, with 1 small spine; mesial face with 2 spines ventrally. Palm about 3.0 times as long as wide; dorsal surface with row of 4 or 6 small spines on midline, dorsolateral margin 3 small spines slightly increasing in size distally, dorsomesial margin with row of 5 spines; dactylar articulation flanked by 2 small spines; mesial face with row of 3 small spines; surfaces covered with small scale-like tubercles; fixed finger straight, terminating in sharp claw, with 2 small subterminal spines and 2 or 3 small, widely spaced spines on lateral margin, cutting edge serrated with row of tiny, acute or subacute teeth or denticles. Dactylus subequal in length to palm, dorsal surface with row of minute, bifid tubercles laterally, terminating in sharp, curved claw crossing tip of fixed finger; mesial margin with 1 small spine at base; cutting edge with row of tiny blunt or subacute teeth or denticles over entire length, no hiatus between closed fingers. Setation on merus consisting of mixture of long iridescent setae and dense plumose setae; mesial faces of carpus and chela with long iridescent setae; scale-like tubercles on carpus and chela each bearing short plumose setae on distal edge.

Ambulatory legs (second to fourth pereopods) moderately long and slender, decreasing in length posteriorly. Second pereopod ( Fig. 4 C), when anteriorly extended, overreaching tip of rostrum by mero-carpal articulation, about twice of carapace length; merus 0.9 times as long as carapace, extensor margin with row of numerous setae and 11 distally curved spines increasing in size distally, flexor margin with strong distolateral spine followed by 1 smaller spine and scale-like ridges, lateral face with small scale-like ridges and granules, mesiodistal angle with small spine; carpus 0.4 length of propodus, with row of 3 (right) or 4 (left) spines increasing in size distally, flexor distal margin produced in spine, lateral face with weak longitudinal ridge dorsally, otherwise with low, scale-like tubercles; propodus with row of short transverse ridges, bearing various setae, on extensor margin, lateral face with few minute granules and few long setae, flexor margin with row of 13 evenly spaced movable spines, all but distalmost spine arising from low protuberances, distalmost spine supported by contiguous fixed acute spine; dactylus ( Fig. 4 D) about half length of propodus and 4.5 times longer than greatest width, slightly curved distally, bearing sparse short to long stiff setae, flexor margin gently sinuous, with 8 corneous spinules plus 1 slender subterminal spinule contiguous with unguis, increasing in length distally, over entire length, each spinule arising from low protuberances. Third pereopod ( Fig. 4 E) similar to second pereopod, though shorter; merus with 10 spines on extensor margin, flexor margin laterally with 1 strong distolateral spine followed by 2 smaller spines and scale-like ridges or tubercles; carpus with 4 spines on extensor margin; propodus with 15 movable spines on flexor margin; dactylus with 8 corneous spinules on flexor margin. Fourth pereopod ( Fig. 4 F) not reaching anterolateral angle of carapace by mero-carpal articulation; ischium with tiny distal spine on extensor margin; merus about 0.6 length of that of second pereopod, with row of 4 spines on distal half of extensor margin, flexor margin laterally with 1 strong distal spine followed by some small spines and scale-like ridges; carpus with 3 spines on extensor margin and prominent spine at flexor distal angle; 10 or 11 movable spines on flexor margin; dactylus with 7 or 8 corneous spinules on flexor margin.

Merus of fifth pereopod with low, scale-like tubercles on lateral surface.

Uropodal exopod with lateral margin faintly denticulate, with minute movable spinules; outer surface with 2 rows of low, scale-like tubercles, distal edge of each tubercle multidenticulate or with 1 or few minute movable spinules. Endopod ( Fig. 3 C) with lateral margin faintly denticulate, bearing minute movable spinules; outer surface with low, scale-like tubercles, distal edge of those tubercles smooth to multidenticulate, occasionally having 1–3 movable spinules; posterior margin roundly truncate, with row of minute movable spinules. Uropodal protopod ( Fig. 3 C) with few transverse striae or ridges on outer surface; posterior inner angle with small spine.

Colouration in life. See Fig. 5 . Carapace dorsal surface alternated by pink (behind epigastric spines, along cervical and transverse grooves and along cardiac region) and yellow-orange bands (gastric region and behind cervical groove); dorsal and marginal spines whitish with red tips. Rostrum and supraocular spines orange, middorsal line and proximal part white. Pleon generally pink, transverse grooves anterior to ridges whitish. Chelipeds and pereopods also generally pink; in chelipeds, bases of spines and scale-tubercles reddish, tips of spines white, distal halves of fingers red. Setae on mesial margins of chelipeds and dorsal margins of meri and carpi of ambulatory legs iridescent.

Distribution. Previously known from New Caledonia and Loyalty Islands ( Macpherson 1994), Kei Islands, Indonesia ( Baba 2005), and New Zealand ( Yaldwyn & Webber 2011); 245– 610 m. The present specimen greatly extends the geographical range of the species to the north, suggesting that the species is widely distributed in the western Pacific.

Remarks. Munida zebra was originally described on the basis of material from New Caledonia and Loyalty Islands, Southwest Pacific, at depths of 200– 610 m. Later, Baba (2005) and Yaldwyn & Webber (2011) recorded the species from Kei Islands, Indonesia, at a depth of 245 m, and from New Zealand (Northland Plateau to Bay of Plenty) at depths of 200–600 m, respectively. The present specimen agrees well with the original description of M. zebra by Macpherson (1994) and the diagnosis by Baba (2005), particularly in the following key characters: (1) carapace branchial margin with four spines; (2) no granules on thoracic sternites 7 and 8; (3) pleomere 2 with 4 pairs of spines on anterior ridge; (4) pleomere 3 unarmed; (5) cornea moderately large; (6) basal article of antennular peduncle not elongate, with distal spines subequal in length; (7) merus of third maxilliped on extensor distal margin; (8) dactyli of second to fourth pereopods armed with accessory spinules along whole length of flexor margin. The characteristic, beautiful living coloration of the specimen also generally agrees with that of M. zebra described and illustrated by Macpherson (1994: fig. 89), in particular the carapace with broad transverse bands. The distomesial spine on the second article of the antennal peduncle seems to be less developed in the present Japanese specimen, compared with the figure of the holotype given by Macpherson (1994: fig. 63c), but this might be in range of intraspecific variation.

Macpherson (1994) compared M. zebra with M albiapicula Baba & Yu, 1987 , only known from Taiwan and M erato Macpherson, 1994 from New Caledonia and Chesterfield Islands. Baba (2005) discussed additional differentiating characters between M. zebra and M. albiapicula .

Figures

FIGURE 3. Munida zebra Macpherson, 1994, female (cl 17.5 mm), CBM-ZC 11349. A, carapace, pleon and cephalic appendages, dorsal view (setae on carapace ridges and striae omitted; distal 2 articles of antennular peduncles omitted); B, thoracic sternite, ventral view; C, pleomere 6, telson and right uropod, outer view (setae on striae on pleomere 6 shown); D, basal article of left antennular peduncle, antennal peduncle and anterior part of pterygostomial flap, ventral view; E, left third maxilliped, lateral view (setae omitted); F, left cheliped, merus, dorsal view (setae omitted); G, same, carpus and chela, ventral view (setae omitted). Scale bars: A, F, G = 5 mm; C – E = 2 mm.

FIGURE 4. Munida zebra Macpherson, 1994, female (cl 17.5 mm), CBM-ZC 11349. A, left cheliped, merus and carpus, ventral view (setae omitted); B, same, chela, ventral view; C, left second pereopod, lateral view; D, same, dactylus and distal part of propodus, lateral view; E, left third pereopod, lateral view (setae omitted); F, left fourth pereopod, lateral view (setae omitted). Scale bars: A – C, E, F = 5 mm; D = 2 mm.

FIGURE 5. Munida zebra Macpherson, 1994, female (cl 17.5 mm), CBM-ZC 11349, habitus in dorsal view, showing colouration in life.