Ctenocheloides boucheti, Poore, Gary C. B., 2015

Poore, Gary C. B., 2015, Ctenocheloides boucheti n. sp., a new ghost shrimp from Papua New Guinea (Decapoda, Axiidea, Ctenochelidae), Zootaxa 3955 (1), pp. 142-146 : 143-145

Ctenocheloides boucheti n. sp.

Figs 1–3

Material examined. Holotype. Papua New Guinea, Madang Province, Kranket I., 0 5°11.5'S, 145°49.1'E, 15 m, 6 Nov 2012 ( PAPUA NIUGINI stn PB03), MNHN IU- 2013-66 (female, cl. 4.0 mm).

Paratypes. Collected with holotype, MNHN IU- 2013-12301 (male without chelipeds, cl. 2.6 mm). S of Urembo I., outer slope, 0 5°15.9'S, 145°47.1'E, 9–11 m, 7 Dec 2012 ( PAPUA NIUGINI stn PB40), MNHN IU- 2014-10407 (male without chelipeds, cl. 4.2 mm).

Diagnosis. Eyestalk with acute distal lobe, elevated in male. Pereopod 1 (cheliped) ischium with toothed lower margin, the most distal tooth bifid; merus with obscure teeth; fingers each with about 20 irregular teeth along cutting edges; fingers 1.25 times as long as upper margin of propodus. Telson 0.9 times as long as wide. Antennular and antennal peduncles reaching similar lengths, each 1.9 times basal eyestalks width. Uropodal exopod 1.4 times as long as wide.

Description of female holotype. Cephalothorax length 0.25 total length, about 1.9 times as long as greatest depth; rostrum rounded; gastric region elevated compared with frontal region, cardiac region with low rounded cardiac prominence; cervical groove well defined, reaching 0.75 length of cephalothorax; linea thalassinica complete; branchiostegite with convex anterodorsal region defined by oblique groove, a second oblique groove over most of length; anterior branchiostegal lobe prominently projecting.

Pleomeres 1 and 2 about equally long, together almost as long as pleomeres 3–6; pleomeres 3–5 with patches of lateral plumose setae; pleomere 6 with lateral semicircular row of setae.

Eyestalk about twice as long as basal width, reaching midpoint of antennular article 2, concave dorsally, apically acute in dorsal and lateral views; cornea depressed, not domed.

Antennule peduncle 1.9 times basal width of eyestalks; articles 2 and 3 subequal. Antenna peduncle reaching about as far as antennule; article 1 with blunt lobe on lower margin; with distinct articulating broad acicle; article 5 0.7 length of article 4.

Maxilliped 2 without arthrobranch, epipod or exopod. Maxilliped 3 ischium-merus 6 times as long as wide; palp as long as ischium-merus; ischium with obsolete crista dentata of 5 irregular teeth; merus with strong mesial tooth, extension of crista dentata ridge bearing 2 strong triangular teeth; dactylus with 1 stronger seta (unguis) among numerous finer setae.

Right cheliped (pereopod 1) ischium with row of small sharp teeth and distal bifid tooth on lower margin; merus 2.1 times as long as broad, lower margin barely convex, with 1 small tooth at midpoint and larger one more distally; propodus 3.5 times as long as greatest depth, palm moderately swollen, fixed finger and dactylus each 1.25 times as long as upper margin, with about 20 irregular teeth along cutting edges, apices sharply curved, fingers curved mesially.

Left cheliped unknown.

Pereopod 2 merus-propodus with lower marginal rows of long setae; carpus 0.6 length of merus, 1.8 times as long as broad; propodus little longer than carpus; fixed finger cutting edge with oblique triangular teeth prominent in second quarter; dactylus with oblique teeth becoming plate-like distally; each finger with corneous tip. Pereopod 3 propodus twice as long along upper margin as wide, with clusters of setae on lower margin, 1 distal spiniform seta. Pereopod 4 propodus 3.8 times as long as wide, with distal spiniform seta. Pereopod 5 propodus with short finger about third length of dactylus, with 2 spiniform setae; dactylus twisted, with spiniform unguis.

Pleopod 1 of female of 1 linear article with undulating mesial margin. Pleopod 2 endopod 3.2 times as long as greatest width; appendix interna attached 0.65 along mesial margin, linear. Pleopods 3–5 similar.

Uropodal endopod with sharply rounded proximolateral corner, distally rounded, 1.4 times as long as wide; exopod ovate, 1.4 times as long as wide, margin with 21 spiniform setae increasing is size and curvature distally; both rami with rows of marginal plumose setae. Telson 0.9 times as long as wide, tapering from parallel-sided base to narrowly rounded apex.

Maxilliped 3 to pereopod 4 each with 2 arthrobranchs, without epipods or pleurobranchs.

Male. Eyestalk distally truncate in lateral view, apices upturned as small points. Pleopod 1 with broad basis and narrow tapering tip, 3 mesial marginal seta, 1 apical seta. Pleopod 2 endopod 3.5 times as long as wide; appendix masculina not reaching apex of endopod, with apical and facial setae; appendix interna almost reaching apex of appendix masculina.

Colour. Body whitish, cheliped fingers orange, ovary orange, bases of antennal flagella bright red.

Distribution. Madang Province, Papua New Guinea.

Etymology. For Philippe Bouchet, organiser of the Madang and many other marine diversity expeditions.

Remarks. Ctenocheloides boucheti differs from the other species of this genus in having more acute distal lobe on the eyestalk, more prominent distal bifid tooth on the cheliped ischium, longer cheliped fingers, shorter telson and the antennular and antennal peduncles reaching similar lengths. With only a single cheliped available, placement of this species in Kiictenocheloides would be a possibility but the new species differs from K. nomurai in the shape of the telson, absence of setae over the abdomen, shape of the eyes, relative lengths of the antennae and antennules, pereopod 5 and colour.

Anker & Pachelle (2013) were uncertain about the presence of gills on maxilliped 2. Komai (2013) reported a slender strap-like epipod on K. nomurai . No gills or epipods were found on this species. Anker & Pachelle (2013: 489, fig. 2g) reported and illustrated a small lobe that they were unable to identify—its shape conforms with one half of the lower lip that sits in a shallow cavity on the posterior face of the mandible.

Figures

FIGURE 1. Ctenocheloides boucheti n. sp. Holotype female. Colour photo by Tin-Yam Chan.

FIGURE 2. Ctenocheloides boucheti n. sp. Holotype female. a, lateral view. b, dorsal view of carapace, eyes, antennule, antennule. c, d, right pereopod 1 in upper and lateral view. e, telson and left uropod. f, g, left pleopods 1 and 2. Paratype male. h, eyes and antenna. i, j, left pleopods 1 and 2.

FIGURE 3. Ctenocheloides boucheti n. sp. Holotype female. a, b, right maxilliped 3, with detail of crista dentata and merus. c, d, left pereopod 2 with detail of fingers. e, f, left pereopod 3, with detail of dactylus. g, h, left pereopod 4, with detail of dactylus i – k, left pereopod 5 with details of fingers from other views. Scale bar applies to whole limbs only.