Coralliocaris junckeri, Li, Xinzheng & Poupin, Joseph, 2012

Li, Xinzheng & Poupin, Joseph, 2012, Coralliocaris junckeri, a new pontoniine shrimp species (Crustacea: Decapoda: Palaemonidae) from Futuna Island, Central Pacific, Zootaxa 3224, pp. 41-48 : 41-47

Coralliocaris junckeri , sp. nov.

( Figs. 1–4 )

Coralliocaris sp. — Poupin & Juncker, 2008: 32, pl. 1e (specimen described herein).

Material examined. 1 ovigerous Ƥ (cl 3.5 mm), holotype, Wallis & Futuna, CRISP 2007 expedition, 14 October 2007, station 14, Futuna Island, Vainifao reef, 14°18’32’’S, 178°08’30’’W, snorkeling in low intertidal, coll. M. Juncker, in coral, with pincers, MNHN-Na 17054.

Diagnosis. Rostrum unarmed; slightly overreaching disto-medial margin of basal segment of antennular peduncle; antennular peduncle with ventral surface of basal segment without spine or tooth along medial margin; first pereopod with fingers not forming concavity on medial surface when closed; second pereopods large, robust, fingers 0.4 times length of palm, forming medial concavity when closed, with stout hooked tips, outer margin of dactylus with proximal half nearly straight, distal half evenly rounded, medial surface with well developed flange forming longitudinal ridge, fixed finger with medial surface with well developed flange forming longitudinal ridge; palm subcylindrical, swollen, robust, 1.8 times maximum width, maximum width at proximal 0.4 of length.

Description. Body (fig. 1A) distinctly depressed; integument smooth.

Carapace (fig. 1A, B, C) with strong left antennal spine, right antennal spine abnormally absent; anterolateral margin rounded; postorbital socket distinct for fitting eye. Rostrum (fig. 1A, B, C) slender, slightly overreaching disto-medial margin of basal segment of antennular peduncle; dorsal and ventral margins unarmed; supraorbital eave regularly expanded posteriorly, not angled.

Fourth thoracic sternite without process.

Abdomen (fig. 1A, E) forming large marsupium with broadly expanded pleurae on anterior three somites, pleopods and posterior part of abdomen, with more than 60 eggs; third somite with dorsal length slightly longer than second somite, slightly produced posterodorsally; pleurae of fourth and second somites rounded posteroventrally; sixth somite slightly longer than deep, with posterolateral lobe rounded. Telson (fig. 1D) 2.2 times as long as greatest width, 0.5 of carapace length, with two pairs of small dorsolateral spines at 0.5 and 0.8 of telsonal length, spine length about 0.05 of telsonal length; posterior margin nearly straight, with three pairs of spines, lateral pair shortest, similar to dorsolateral spines; intermediate pair thickest and longest, about 0.1 of telsonal length, about 2.6 times as long as lateral spine, submedian pair 0.5 of intermediate spine in length.

Eyes (figs. 1, 2A) with globular cornea; eyestalk elongate, subcylindrical, posterior margin length 1.3 times longer than wide.

Antennular peduncle (fig. 2B) reaching 0.8 of length of scaphocerite; medial margin length of basal segment as long as greatest width; lateral margin roundly convex, anterolateral lobe well developed, overreaching distodorsal margin of second (intermediate) segment, near to distal end of medial margin of second segment, terminating in an acute tooth on left, rounded (without tooth or spine) on right; ventral surface without spine or tooth along medial margin; stylocerite well developed, reaching near to distal margin of anterolateral lobe; intermediate segment with length of medial margin 0.5 of length of medial margin of basal segment, 0.8 times greatest width, with row of several long plumose setae on medial margin; distal segment with length of medial margin 0.3 of length of medial margin of basal segment, 0.7 times greatest width, distinctly widened distally; upper flagellum biramous, fused part composed of nine segments, with about 22 groups of aesthetascs, shorter branch with three segments, longer branch with about 15 segments, lower flagellum with about 34 articles, as long as carapace length. Antenna (fig. 2C) with carpocerite reaching to about 0.7 of length of scaphocerite; basicerite with robust distolateral spine; length of scaphocerite 0.6 of carapace length, 2.0 times greatest width, lateral margin nearly straight; distolateral spine of scaphocerite much shorter than distal margin of blade.

Mouthparts based on left side, except mandible. Mandible (fig. 2D) deeply divided into incisor and molar processes, without palp; incisor process tapering distally, (left mandible incisor process) armed with three small teeth. Maxillule (fig. 2E) with bilobed palp, upper lobe short, with three spiniform apical setae, lower lobe unarmed; basal endite tapering distally, apex rounded, with finely serrate apical spines; coxal endite stout, apex blunt, with spiniform setae. Maxilla (fig. 2F) with short simple palp armed with single spine at about distal third; endite greatly reduced to single lobe, bearing long apical setae, reaching to half length of palp length, scaphognathite well developed, about 1.8 times longer than central width, fringed with plumose setae. First maxilliped (fig. 2G) bearing several long apical setae and short subapical-medial spiniform setae on flagellum; caridean lobe broad, subrectangular, fringed with plumose setae; endopod palp rudimatory; epipod large, bilobed; basal and coxal endites almost completely fused, basal endite rounded, unarmed marginally, coxal endite well developed, bearing long spiniform setae along medial margin and few short simple setae along upper margin. Second maxilliped (fig. 2H) with dactylar segment with stout spiniform setae along medial margin and row of spiniform setae on posterior surface; propodus not produced anteriorly, with setae on anteromedial angle; epipod feebly developed. Third maxilliped (fig. 2I) with stout endopod; basis incompletely fused with ischiomerus, medial margin produced medially, with several long simple setae; ischiomeral part about 1.4 times central width, with simple setae along medial margin; penultimate segment about 0.7 of length of ischiomerus, 1.1 times central width, convex medially, with dense short fine setae on medial margin; terminal segment as long as penultimate segment, 1.8 times maximum width, distal half of medial margin with dense fine short setae, disto-medial part with rather long curved spiniform setae; epipod large, rounded; arthrobranch with three lamellae; exopodal flagellum slightly overreaching distal end of endopod when extended, fringed with plumose setae distally.

First pereopod (fig. 3A, B) slender; chela 0.6 times as long as carpal length; fingers (fig. 3B) about half of length of palm, with several tufts of long fine setae on lateral surfaces and hooked tips, cutting edges blunt, broadest at base, tapering distally, lateral margins of cutting edges entire; dactylar length 2.9 times proximal width; palm 1.6 times as long as maximum width, with several tufts of long recurved setae on ventromedial surface, tuft of short cleaning setae present on proximal medioventral surface; carpus about 0.6 of carapace length, as long as merus, with row of long setae at distomedial part corresponding to cleaning setae on palm; ischium about 0.33 of length of merus.

Second pereopods (fig. 3C, D) large, robust, subequal and similar; chela large, heavy, robust, about 1.7 of carapace length; fingers (fig. 3D) 0.4 of length of palm, with medial cavity, with stout hooked tip, dorsal margin rounded, with tufts of setae; dactylus with cutting edge with large subtriangular tooth at proximal 0.33 of length, medial surface with well developed flange forming longitudinal ridge; fixed finger having cutting edge with large subtriangular tooth at middle of cutting edge and proximal tooth-like lobe, with notch between tooth and lobe, subapical cutting edge concave, medial surface with well developed flange forming longitudinal ridge; palm subcylindrical, swollen, robust, maximum width at proximal 0.4 of length, 1.8 times of maximum width; carpus short, cuplike, about 0.33 as long as palm, as long as distal width, with distomedial process; merus compressed, about 0.5 of length of palm; distomedial process triangular; ischium compressed, subtriangular, dorsal length about 0.25 as long as palm, 1.1 times distal width.

Third to fifth pereopods (fig. 3E, F) similar, robust; each dactylus short, distally round, flexor surface with strongly curved hook-shaped protuberance; propodal length of third pereopod about 0.5 of carapace length, 4.0 times as long as dactylar length, 3.2 times depth, with few groups of long setae on distodorsal margin; carpus about 0.4 times as long as propodus, as long as deep, with distodorsally produced lobe; merus about 1.2 times of propodal length, slightly tapering distally, 2.1 times proximal depth; ischium short, widened distally, 0.4 times of propodal length, 0.9 of distal wide; coxa and base without special features.

Pleopods well developed; exopod of third pleopod slightly longer than endopod, 0.75 of carapace length, appendix interna of third pleopod raising from proximal 0.2 of mesial margin, 0.33 times endopodal length. Uropod (fig. 1D) far overreaching tip of telson; protopodite rounded posterolaterally; exopod 1.2 times of telsonal length, 2.4 times as long as maximum width, lateral margin straight, with acute immovable distolateral tooth and movable spine medially, diaeresis 0.33 of total exopodal length, suture distinct; endopod 0.9 of exopodal length, 2.9 of maximum width.

Colouration. Based on a color photograph taken just after the collecting event ( Fig. 4 ), Coralliocaris junckeri sp. nov. overall white with pale pink shades on tip of rostrum, scaphocerites, antennular peduncles, fingers of chelae of second pereopods, pereopods 3–4, and abdominal pleurites. Tailfan white on proximal third and light brown on distal two third.

Host. This shrimp was collected with pincers in coral branches, most probably in a Pocillopora sp., a coral very common at CRISP-2007 station 14.

Etymology. This new species is dedicated to Matthieu Juncker who has collected the shrimp while snorkeling at low tide.

Remarks. To date, there have been eleven species placed in the genus Coralliocaris including the new species. Coralliocaris junckeri sp. nov. can be readily distinguished from C. macrophthalma (H. Milne Edwards, 1837) , C.

graminea ( Dana, 1852) , and C. viridis Bruce, 1974 by the dactylus of the second pereopod with lateral margin straight in proximal half and hooked curved in the distal half, vs the lateral margin of the second pereopod dactylus strongly convex and semicircular in these three species. The form of the second pereopod dactylus of the new species is also distinct from that of C. superba ( Dana, 1852) and C. taiwanensis ( Fujino and Miyake, 1972) . These two species have the lateral margin of the second pereopod dactylus abruptly angled. The dactylus of the second pereopod has a longitudinal ridge on its medial surface which is absent in C. brevirostris Borradaile, 1898 and C. tridens Mitsuhashi, Fujino and Takeda, 2001 . Coralliocaris labyrintha Mitsuhashi & Takeda, 2008 and C. nudirostris Heller, 1861 have the outer margin of the second pereopod dactylus sinuous, which is different from the situation in the new species. Coralliocaris junckeri sp. nov. also differs from C. labyrintha by the slight evenly convex lateral margins of the rostral eave, the latter has the rostral eave smoothly angled; it also differs from C. taiwanensis by the fingers of the first pereopod not forming concavities on their medial surfaces when the fingers are closed, the latter has the fingers of the first pereopod forming concavities on the medial surfaces when the fingers are closed. The new species is very close to C. sandyi Mitsuhashi & Takeda, 2008 in morphology, but can be distinguished by the more stout second pereopods, the palm in the new species is swollen, 1.8 times as long as its maximum width, that of C. sandyi is nearly uniform in its whole length, not swollen, nearly 3.0 times as long as its maximum width. The colour patterns of C. junckeri and C. sandyi are very different, that of C. junckeri is whitish with distal parts of the body red to orange, the colour of C. sandyi is green with fine dark longitudinal striae ( Mitsuhashi & Takeda, 2008) like that in C. graminea ( Dana, 1852) .

In fact, the new species can be distinguished from most of the congeneric species by the unarmed rostrum. With exception of C. nudirostris Heller, 1861 , C. sandyi Mitsuhashi & Takeda, 2008 , C. brevirostris Borradaile, 1898 and the new species, other species in the Coralliocaris have the rostrum dorsally armed with teeth. However, according to Mitsuhashi & Takeda (2008), C. nudirostris and C. sandyi have either armed or unarmed rostral forms, which implies that an armed or unarmed rostrum is not a stable feature to distinguish sibling species in the genus.

Figures

FIGURE 1. Coralliocaris junckeri, sp. nov., holotype ovig. Ƥ (cl 3.6 mm) (MNHN-Na 17054). A. Body, dorsal view; B, carapace, lateral view; C, anterior carapace, dorsal view; D, caudal fan and posterior abdomen, dorsal view; E, abdomen, lateral view. Scale bars: 1.0 mm.

FIGURE 2. Coralliocaris junckeri, sp. nov., holotype ovig. Ƥ (cl 3.6 mm) (MNHN-Na 17054). A, left eye, ventral view; B, left antennule, dorsal view; C, left antenna, ventral view; D, right mandible, posterior view; E, left maxillula, anterior view; F, left maxilla, posterior view; G, left first maxilliped, posterior view; H, left second maxilliped, posterior view (epipod omitted); I, left third maxilliped, posterior view. Scale bars: A – C, I, 1.0 mm; D – H, 0.5 mm.

FIGURE 3. Coralliocaris junckeri, sp. nov., holotype ovig. Ƥ (cl 3.6 mm) (MNHN-Na 17054). A, left first pereopod, ventral view; B, same, chela, dorsal view; C, left second pereopod, dorsal view; D, same, fingers, ventral view; E, left third pereopod, posterior view; F, same, dactyl and distal part of propod, posterior view. Scale bars: A – E, 1.0 mm; F, 0.5 mm.

FIGURE 4. Coralliocaris junckeri, sp. nov., holotype ovig. Ƥ (cl 3.6 mm) (MNHN-Na 17054). Live coloration, dorsal view (photographed by J. Poupin).