Alcyonohippolyte commensalis Kemp 1925, comb. nov.
Creators: name: Marin, Ivan
name: Okuno, Junji
name: Chan, Tin-Yam
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Hippolytidae
Alcyonohippolyte
Alcyonohippolyte commensalis

description: Alcyonohippolyte commensalis (Kemp, 1925) comb. nov.
(Figs. 5–11, 14 A–C, 15A, 16B)
Hippolyte commensalis Kemp, 1925: 331 (? part), figs. 21–22 [type locality: Nancowry Island, Nicobars]. — Bruce, 1975: 24, fig. 6; 1976: 50. — Hayashi, 1986: 20 (part). — Holthuis, 1995: 146 (part). — Minemizu, 2000: 102, unnumbered fig.— Kawamoto & Okuno, 2003: 58, unnumbered fig.
Material examined. Japan: 4 males (pcl. 1.2–1.6 mm), 1 ovigerous female (pcl. 2.2 mm, tl. 9 mm) (RUMF), Ryukyu Islands, Okinawa, Motobu Peninsula, Sesoko-jima Island, from Xenia sp., coll. Y. Fujita, 19 Jul. 1998; 2 ovigerous females (pcl. 2.3 and 2.8 mm), (CMNH –ZC 02394), Ogasawara (Bonin) Island, Chichi-jima Island, Hyotan-jima Islet, 12 m, from Xenia sp., coll. O. Morishita, Jun. 2000; 1 ovigerous female (pcl. 1.6 mm) (CMNH – ZC 02393), Ryukyu Islands, Kume-jima, Tonbara, 30 m, coll. T. Kawamoto, 23 Jan. 2002. Australia: 4 ovigerous females, 3 females (QM W33475), Great Barrier Reef, Lizard Island, lagoon, patch reef, LI10-037, 14°41.202’S 145°27.307’E, snorkeling, 0.5–1.5 m, on Xenia sp., coll. I. Marin, 30 Aug. 2010; 1 male (pcl. 1.5 mm, tl. 8 mm), 3 ovigerous females, 1 female (QM W33478), beach in front of marine station, LI10-030, 14°41.171’S 145°27.302’E, snorkeling, 0.5–1.5 m, on Xenia sp., coll. I. Marin, 31 Aug. 2010; a male, 1 ovigerous female (pcl. 2.8 mm), 2 females, (QM W33476), beach in front of marine station, LI10-020, 14°38.761’S 145°27.215’E, snorkeling, 0.5–1.5 m, on Xenia sp., coll. I. Marin, 29 Aug. 2010; 11 males, 3 ovigerous females, 6 females (QM W33477), lagoon, patch reef, LI10-039, 14°41.229’S 145°27.296’E, snorkeling, 0.5–1.5 m, on Xenia sp., coll. I. Marin, 31 Aug 2010.
Diagnosis. Female (CMNH–ZC 02393). Carapace smooth, non-gibbous dorsally (Fig. 5); with supraorbital, antennal and hepatic teeth, antennal tooth situated considerably lower than inferior orbital angle, hepatic tooth larger than antennal tooth, situated below and behind level of antennal tooth. Rostrum long, slender, unarmed dorsally, with single subapical ventral tooth (Figs. 6 C), with proximal lateral lamina armed with supraorbital tooth at level of proximal margin of orbit (Fig. 6 A). Orbit well developed, inferior orbital angle produced distally, blunt (Fig. 6 C). Abdominal somites smooth, pleura of abdominal somites I–V rounded (Fig. 5). Telson (Fig. 6 E) slender, about 3.5 times as long as proximal width, narrowing distally, generally with 2 pairs of small dorsal submarginal spines at 0.55 and 0.75 of telson length; distal margin of telson armed with 4 pairs of spines. Eyes normal, large, with subovate cornea. Antennule (Fig. 6 F) well developed; basal segment without ventromedial tooth, distolateral angle bearing large acute tooth. Antenna (Fig. 6 G) well developed, basicerite with triangular distoventral tooth; scaphocerite wide, about twice longer than maximal width, with well developed acute distolateral tooth. Mandible robust (Fig. 7 A), without palp; incisor process reduced, slender, styliform, with pointed tip; molar process robust, with stout sharp distal teeth. Maxillula (Fig. 7 B) normal, with well developed bilobed palp, ventral lobe armed with long simple setae; upper lacinia wide, with convex ventral margin, flaring distally, with numerous stout setae along distoventral margin, bearing 2–3 long plumose setae at distodorsal angle; lower lacinia more slender, tapering distally, covered with long simple setae. Maxilla (Fig. 7 C) with simple blunt palp, endites completely fused, armed with small stout setae, with few long plumose setae at distodorsal angle; scaphognathite well developed, fringed with plumose setae. Maxilliped I (Fig. 7 D) with completely fused endites, armed with small stout setae along distal margin, with few elongated plumose setae at distodorsal angle; exopod well developed, with well marked caridean lobe furnished with plumose setae; epipod rectangular, bilobed distally. Maxilliped II (Fig. 7 E) with well developed stout exopod; ischium stout, with long plumose setae along lateral margin; propodal segment small, length equal to dactylar segment, with convex dorsal margin furnished with long simple setae, ventral margin unarmed; dactylar segment convex, armed with dense long stout simple setae along distal margin; epipod well developed, distally bilobed. Maxilliped III (Fig. 7 F) large and stout; exopod small, reduced, reaching midlength of ischiomeral segment; ischiomeral segment about 3 times as long as width, slightly tapering distally; penultimate segment about 2.5 times as long as wide, smooth; terminal segment with distal margin oblique, armed with row of strong spines distally; coxal segment with well developed arthrobranch. Pereiopod I (Fig. 8 A) normal, with segments stout and unarmed; coxa with arthrobranch; basis with small lobe distoventrally; carpus stout, shorter than merus and equal to length of propodus, about as long as wide, flaring distally, distal margin overlapping carpo-propodal articulation, with row of stout plumose setae along distoventral margin (Fig. 8 B); palm about as long as wide, subcylindrical, smooth; fingers (Fig. 8 C) stout, slightly longer than palm, subspatulate, cutting edges armed with several large acute teeth. Pereiopod II (Fig. 8 D) relatively slender, with segments unarmed; coxa with small arthrobranch; basis with small lobe distoventrally; carpus subdivided into 3 subsegments and with ratio of 2:1:2 or 2:1:2.3; palm subcylindrical, length equal to distal carpal segment, with straight smooth margins; fingers robust, subspatulate, equal to length of palm, cutting margins armed with several large acute teeth (Fig. 8 E). Pereiopod III–V (Fig. 8 F, H, I) similar, segments smooth and relatively slender; meri each with large movable spine at distoventral angle; propodi with unarmed ventral margin, with or without minute distoventral spinules; dactyli (Fig. 8 G) slender, simple, with elongate curved unguis, without accessory tooth. Distolateral margin of uropodal exopod without fixed tooth, bearing only single long movable spine (Fig. 6 D).
Males (RUMF). Generally similar to females, but smaller in size (Fig. 5). Rostrum unarmed (Fig. 9 A), styliform, pointed distally. Propodus of pereiopod III (Fig. 9 D, E) with 3 pairs of spines along distoventral margin, proximal most pair about twice larger than others.
Coloration. The collector of the type material, R. B. Seymore Sewell, mentioned that “ the prawns were a white with the pale brown markings imitating the shadows cast by the polyps and their tentacles ” (see Kemp, 1925). Color photographs of A. commensalis have been provided by Bruce (1975), Minemizu (2000) and Kawamoto & Okuno (2003). The color pattern of the species is as follows: ground color of carapace and abdomen dark green; rostrum white, continuing white broad longitudinal band of dorsal midline running from carapace to abdominal somite VI; carapace with gastrofrontal region bearing white reticulate stripes, two white oblique bands running through branchiocardiac and ventrolateral parts of carapace, downwards anteriorly, former band continuing with band on dorsal midline, latter band continuing with band running through abdominal pleura I–IV; telson and uropods greenish transparent, covered with dark green marbling; cornea golden yellow, eyestalk with bluish white transverse bands; scaphocerite white, dorsally with green spots; pereiopods greenish transparent, covered with dark green marbling (Figs. 11, 15 A, 16B).
Remarks. Kemp (1925) described Hippolyte commensalis from material collected by R. B. Seymore Sewell at the Nicobar Islands (catalog number C 912/1). As was recorded by Sewell, “ these shrimps, together with (white) portuniid, were found among the tentacles of compound Actinian ” (Kemp, 1925). It is likely that the “ compound Actinian ” is a soft coral Xenia sp. (Octocorallia, Alcyonacea, Xeniidae) usually inhabited by specialized symbiotic portuniid crabs of the genus Caphyra Guérin-Méneville, 1832 (Brachyura, Portunidae, Caphyrinae, pers. observ.). The description and drawings given by Kemp (1925) show a toothless rostrum, and all the Australian material also shows a toothless rostrum (Fig. 10 A). However, specimens from Japan have rostrum bearing a distinct ventral tooth and only a single female possesses small subapical ventral tooth (Fig. 14 A). Moreover, some females from Japan have a pair of small spinules at the distoventral angle of the propodus of pereiopod III (Fig. 8 G). Nevertheless, all other features described by Kemp (1925) are identical with the present material. The standard Japanese name for this species is Azami-kakure-moebi.
Host. All examined specimens were collected from colonies of soft corals of the genus Xenia Lamarck, 1816 (Octocorallia, Alcyonacea, Xeniidae).
Size. The largest female (ovigerous) has pcl. 3.0 mm, tl. 16.0 mm, and the largest male has pcl. 1.6 mm, tl. 7 mm.
Distribution. The species is known from the Red Sea (Holthuis 1955), Kenya (Bruce 1976), Nicobar Islands (Kemp 1925; type locality), Japan (Ogasawara and Ryukyu Islands, Minemizu, 2000; Kawamoto & Okuno 2003; present study), the Great Barrier Reef of Australia (present study), Gilbert and Solomon Islands (Hayashi 1986).
description: Published as part of Marin, Ivan, Okuno, Junji & Chan, Tin-Yam, 2011, On the " Hippolyte commensalis Kemp, 1925 " species complex (Decapoda, Caridea, Hippolytidae), with the designation of a new genus and description of two new species from the Indo-West Pacific, pp. 32-54 in Zootaxa 2768 on pages 39-45, DOI: 10.5281/zenodo.206743