Alcyonohippolyte tubiporae, Marin, Ivan, 2011

Marin, Ivan, 2011, Two new species of alcyonacean-associated shrimp genus Alcyonohippolyte Marin, Okuno & Chan, 2010 (Crustacea: Decapoda: Hippolytidae) from the Great Barrier Reef of Australia, Zootaxa 3123, pp. 49-59 : 56-59

Alcyonohippolyte tubiporae sp. nov.

( Figs. 6 , 7 )

Material examined. Holotype, ovigerous female (plc. 2.7 mm, tl. 9 mm), QM W33519, GBR of Australia, Lizard Island area, Lagoon, patch reef, LI10-039, 14º41.229’S 145º27.296’E, 0.5–1.0 meters, on Tubipora sp., coll. I. Marin, 31 Aug. 2010.

Paratypes, 2 ovigerous females (pcl. 3.0 mm, tl. 14 mm; pcl. 2.0 mm) and 1 male (pcl. 1.5 mm), QM W33522, locality and host same to holotype.

Description. Paratype female (QM W33522). Carapace ( Fig. 6 A–C) smooth and naked, dorsal surface non gibbous; with well-marked supraorbital, antennal and hepatic teeth, antennal tooth acute, small, situated slightly below orbital angle; hepatic tooth acute, larger than antennal tooth, slightly exceeding distal margin of carapace, situated below and slightly behind level of antennal tooth ( Fig. 6 A). Rostrum long, compressed, dorsally unarmed, with single subdistal ventral tooth, reaching the distal margin of antennular peduncle, proximal lateral rostral lamina with sharp supraorbital tooth situated above the level of proximal orbital margin ( Fig. 6 b). Orbit well developed, inferior orbital angle slightly produced distally. Pterygostomial angle bluntly projected.

Abdominal somites ( Fig. 6 A) smooth and unarmed, dorsal parts of abdominal somites II–V with some tufts of plumose setae; pleurae of abdominal somites I–V rounded. Telson slender, about 2.5 times as long as proximal width, narrowing posteriorly, with 2 pairs of small submarginal dorsal spines at 0.5 and 0.75 of telson length; distal margin of telson armed with 3 pairs of spines.

Eyes normal, well developed, with subcylindrical eyestalk and subovate cornea; eyestalk about as long as wide; cornea suboval, without papilla.

Antennula ( Fig. 6 D) well developed; basal segment about 1.5 times as long as wide, with small ventromedial tooth, with acute distolateral tooth overreaching midlength of intermediate segment, inner distolateral angle lined with several long setose setae; stylocerite well developed, acute, almost reaching distal margin of basal segment; intermediate segment stout, about twice wider than long, with slightly convex inner lateral margin lined with long plumose setae; distal segment stout, about as long as wide, with long plumose setae along inner lateral margin; proximal part of upper antennular flagellum with 4 segments, shorter ramus with 1 stout segment.

Antenna normal, well developed, basicerite armed with sharp triangular tooth distoventrally, slightly overreaching distal margin of segment; carpocerite stout, about as long as wide, reaching midlength of scaphocerite; flagellum well developed; scaphocerite ( Fig. 6 B) wide, about 1.5 times as long as maximal width, greatly overreaching antennular peduncle, with well developed acute distolateral tooth, not reaching the distal margin of blade.

Mouthparts characteristic for the genus and similar to the species described above.

Pereiopod I ( Fig. 6 E) robust, unarmed; coxa with arthrobranch; basis with small lobe distoventrally; ischium stout, about as long as wide, with long simple setae along ventral margin; merus stout, about twice longer than wide; carpus stout, shorter than merus and equal to the length of propodus, about as long as wide, flaring distally, distal margin overlapping carpo-propodal articulation, with a row of stout setose setae along distoventral margin; palm about as long as wide, subcylindrical, smooth; fingers stout, slightly longer than palm, subspatulate, about as long as wide, cutting edges armed with several large acute teeth.

Pereiopod II relatively slender, segments unarmed ( Fig. 6 F); coxa with arthrobranch; basis with small lobe distoventrally, about as long as wide; ischium about 1.5 times as long as wide, smooth; merus about 3.5 times as long as wide, with straight margins; carpus subdivided into 3 subsegments with ratio of about 1.5: 1: 1.5, proximal segment about 1.5 times as long as wide, about 1.5 times longer than medial (the 2nd) segment, medial segment about as long than wide, about 1.5 times shorter than distal segment; palm subcylindrical, equal to distal carpal segment, about 1.5 times longer than wide, with straight smooth margins; fingers robust, about 0.7 of the length of palm, about twice longer than wide, subspatulate, cutting edges armed with several large acute teeth.

Pereiopods III–V similar, relatively slender, with segments unarmed. Pereiopod III ( Fig. 6 G) with basis about as long as wide; ischium about 2.5 times longer than wide; merus about 3.5 times as long as wide, with straight dorsal and ventral margins, bearing large movable spine at distoventral angle; carpus about 2.5 times as long as maximal width, flaring distally, with distodorsal margin overhanging proximal part of propodus; propodus about 6 times as long as wide, with straight and smooth margins, ventral margin unarmed, with a pair of small spines at distoventral angle; dactylus rather stout, basal part about 1.5 times as long as maximal width, swollen, with elongated and curved main unguis, without accessory tooth.

Pleopods normal. Uropods slender, slightly exceeding telson; distolateral margin of exopod without fixed tooth, with long mobile spine only.

Male paratype (QM W33522). Generally similar to female; slightly smaller in size. Carapace ( Fig. 6 C) naked, dorsal surface of abdominal somites with tufts of small setose setae; rostrum unarmed, styliform, pointed distally, with small subdistal ventral tooth ( Fig. 6 C). Propodus of pereiopod III subchelate, with 3 pairs of spines along distoventral margin, most proximal pair about twice larger than others.

Coloration. Body generally brown, covered with pale white bands ( Fig. 7 ); two thin white oblique bands cross carapace laterally, lower band continue to pleurae of abdominal somites; dorsal surface of the front of carapace, rostrum, eyes, antennula, antenna and scaphocerite white; several large transparent spots situate on abdominal somites II–IV dorsolaterally, abdominal somite VI, telson and uropods; maxilliped III and pereiopods I brown, ambulatory pereiopods II–V completely transparent.

Differential diagnosis. The new species possesses smooth carapace and stout carpal segments of pereiopod II. Normal smooth carapace clearly differs A. tubiporae sp. nov. from Alcyonohippolyte dossena Marin, Okuno & Chan, 2011 having hump back carapace. Alcyonohippolyte commensalis (Kemp, 1925) differs from the new species by carpus of pereiopod II longer than merus, more slender carpal segments (see Marin et al., 2011: fig. 8D) and longer proximal carpal segment of pereiopod II, which is about twice longer than wide and distinctly longer than the distal carpal segment (vs. proximal carpal segment of pereiopod II is about 1.5 times longer than wide and equal to the distal segment in A. tubiporae sp. nov.); chela of pereiopod II is smaller and shorter in A. tubiporae sp. nov. than in A. commensalis . Alcyonohippolyte maculata Marin, Okuno & Chan, 2011 can be clearly separated from the new species by having setose setae on carapace dorsally (see Marin et al., 2011: fig. 13B) and significantly more slender carpal segments of pereiopod II (see Marin et al., 2011: fig. 13H). Alcyonohippolyte tenuicarpus sp. nov., described above, differs from the new species by longer rostrum and more slender carpal segments of pereiopod II (see above).

Host. The species was found in association with organ pipe coral of the genus Tubipora Linnaeus, 1758 , possibly T. musica Linnaeus, 1758 ( Alcyonacea : Tubiporidae ). All shrimp specimens were found on the surface of coral colonies among exposed tentacles of corallites. Shrimps hide between tubes of corallites being disturbed. Etymology. The species is named after its association with organ pipe coral of the genus Tubipora Linnaeus, 1758 , possibly T. musica Linnaeus, 1758 ( Alcyonacea : Tubiporidae ).

Size. The largest female (ovigerous) has pcl. 3.0 mm, tl. 14.0 mm and male has pcl. 1.5 mm, tl. 10 mm. Distribution. The new species is known from the type locality only, Lizard Island, the Great Barrier Reef of Australia.

Figures

FIGURE 6. Alcyonohippolyte tubiporae sp. nov., holotype, ovigerous female, QM W 33519 (A), paratype female, QM W 33522 (B, D – G), paratype male, QM W 33522 (C): A—general view; B—carapace, dorsal view; C—carapace, lateral view; D—antennula; E—pereiopod I; F—pereiopod II; G—pereiopod III.

FIGURE 7. Coloration of Alcyonohippolyte tubiporae sp. nov.: holotype, ovigerous female, QM W 33519 (A, B); paratypes, female (C) and male (D), QM W 33522.