Hamodactylus paraqabai Horká, Fransen & Ďuriš, 2016, sp. nov.
Creators: name: Horká, Ivona
name: Fransen, Charles H. J. M.
name: Ďuriš, Zdeněk
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Palaemonidae
Hamodactylus
Hamodactylus paraqabai

description: Hamodactylus paraqabai sp. nov.
urn:lsid:zoobank.org:act: D50ED903-8CDF-4B68-BE54-8E4F2177FB2B
Figs 1–5, 10 B–C
Etymology
The specific name paraqabai is a noun composed of the prefix para - (from Greek: besides) and the adjective - aqabai, a species name used for H. aqabai, a closely similar species from the Red Sea.
Material examined
Holotype
PAPUA NEW GUINEA: ovigerous ♀ (PoCL 1.5 mm), Madang, Krangket Is., stn PR3, 05°11.3' S 145°49.1' E, lagoon, depth 13 m, on Nephthea sp., 6 Nov. 2012, coll. Z. Ďuriš, fcn PNG12-17 (GenBank acc. nr. KR088751) (MNHN-IU-2013-11092).
Paratypes
PAPUA NEW GUINEA: 1 ovigerous ♀ (PoCL 1.9 mm), same data as holotype (MNHN-IU-2013-10551); 1 ♀ (PoCL 1.6 mm, mouthparts dissected), Madang Resort, 05°12.5' S 145°48.5' E, stn PR227, on Nephthea sp., 10 Dec. 2012, coll. A.F. Berberian, leg. Z. Ďuriš, fcn PNG 12-638 (GenBank acc. nr. KR088752) (MNHN-IU-2013-11090).
Guinea), habitus. Scale bar = 1 mm. Additional material
AUSTRALIA, Great Barrier Reef, Lizard Island, from soft branchy corals (Alcyonacea), coll. & leg. Z. Ďuriš: 1 ♀ (PoCL 1.3 mm), stn LI10-47, 14°41.8' S 145°27.0' E, North Point, South of Mermaid Cove, depth 9 m, on Nephthea sp., 1 Sep. 2010, fcn Au10-78B (GenBank acc. nr. KR088753) (MTQ-33208); 1 ♂ (PoCL 1.1 mm), stn LI10-59, 14°42.0' S 145°26.9' E, lagoon, depth 8.6 m, on Nephthea sp., 2 Sep. 2010, fcn Au10-85 (GenBank acc. nr. KR088754) (MTQ-33218).
Description of holotype
Small sized shrimp, ovigerous female; specimen complete, with all appendages (Fig. 1).
Carapace smooth. Rostrum (Fig. 2A) well developed, exceeding intermediate segment of antennular peduncle (Fig. 2B); lamina deep, lateral carina situated slightly above straight, setose, toothless ventral margin; dorsal margin convex, elevated, strongly compressed, with six subequal teeth, of which first situated above level of posterior orbital margin. Supra-orbital and epigastric spines absent. Orbit obsolescent, inferior orbital angle acutely produced in lateral view. Antennal spine small and slender, marginal, situated closely below inferior orbital angle. Hepatic spine larger and more robust than antennal, situated just behind level of posterior orbital margin and well below level of antennal spine. Antero-lateral angle moderately produced, rounded.
Abdominal segments smooth (Fig. 1). First segment pleuron highly produced anteriorly, third segment not produced posterodorsally, sixth segment twice as long as deep. Pleura all broadly rounded. Posteroventral angle of sixth segment feebly produced, postero-lateral angle feebly acute.
Telson 0.8 of length of sixth abdominal segment and 3.2 times as long as maximum width (Fig. 2C). Lateral margins convex in anterior half, posteriorly converging. Two pairs of very small marginal dorsal spines, about 0.05 of telson length, present at 0.55 and 0.8 of telson length. Posterior margin (Fig. 2D) rounded, about half of anterior width, with three pairs of spines; lateral spines short but distinctly twice as long as dorsal spines. Intermediate spines largest, about 0.2 of telson length and 1.5 times length of more slender, setulose, submedian spines.
Eyes (Fig. 2B) well developed. Cornea ellipsoid, obliquely set on stalks; stalk swollen proximally, with distinct accessory pigment spot anterodorsally.
Antennular peduncle (Fig. 2B) normal, exceeding tip of rostrum by distal segment. Basal segment broad, 2 times as long as wide, with stylocerite slender, acute, reaching almost to middle of segment; lateral border convex, anterolateral margin slightly acutely produced mesially, with 2 acute distolateral teeth (Fig. 2E); medioventral margin with tooth in front of statocyst level. Intermediate and distal segments short, together equal to 0.3 of proximal segment length. Upper flagellum biramous, with first 7 segments fused, shorter free ramus 3-segmented and longer ramus consisting of about 10 slender segments. About 6 groups of aesthetascs present. Lower flagellum consisting of about 11–13 slender segments.
Antenna (Fig. 2B) with robust basicerite without lateral tooth. Carpocerite slender, short, reaching almost to middle of scaphocerite. Scaphocerite large, extending well beyond antennular peduncle, about 2.5 times as long as broad, with greatest width in midlength, distomedially angulated; lateral border almost straight, with acute distal tooth; lamina extending far beyond distolateral tooth.
Fourth thoracic sternite unarmed.
First pereiopod (Fig. 3 A–D) slender, reaching to end of scaphocerite. Chela with palm subcylindrical, slightly bowed and compressed, about 4 times as long as wide. Fingers about 0.75 of palm length; cutting edges gaping distally, bearing series of 5 small blunt teeth at distal third on dactylus, and 3 such teeth on fixed finger; very thin denticulate lamella present laterally along latter series of teeth on both fingers, tip of fingers slender, hooked. Cleaning setae present proximally on palm and on disto-ventral end of carpus, latter being subequal to chela length and 6.5 times as long as wide distally. Merus about 1.3 times as long as carpus and almost twice length of ischium. Basis and coxa normal.
Second pereiopods (Fig. 3 E–F) greatly reduced, small, reaching almost to end of carpocerite, subequal and similar, resembling ambulatory pereiopod. Chela without any trace of fixed finger; dactylus resembles that of walking legs. Unguis distinct, occupying distal 0.25 of dactylus length, corpus slender, 4.2 times as long as basal width, slightly curved, without accessory spines or teeth, long setae arising from distal and subdistal part of corpus. Propodus subcylindrical, unarmed, about 6.5 times as long as wide and 2
molar maxilliped.
process. D. Maxillula. E. Maxilla. F. First maxilliped. G. Second maxilliped. H. Third times length of dactylus; dactylus unarmed. Carpus, merus and ischium unarmed, lengths in ratio of 1.2, 1.0 and 1.6 times length of propodus. Basis and coxa normal.
Ambulatory pereiopods slender, distinctly longer and more robust than second pereiopods. Third pereiopod (Fig. 3G) exceeds tip of scaphocerite by dactylus. Dactylus (Fig. 3H) slender, uniformly tapering, unarmed and with a distinct unguis on distal 0.45 of length, total length about 5 times width near base. Propodus about 12 times as long as wide, 3 times length of dactyl, and devoid of spines. Carpus, merus and ischium 0.5, 0.8 and 0.5 of propodus length, unarmed. Fourth and fifth pereiopods similar, dactylus of fifth pereiopod (Fig. 3I) slightly more slender and straighter than that of third leg.
Uropods (Fig. 2C) slender, extending well beyond tip of telson. Protopodite unarmed laterally. Exopod about 3 times as long as wide, extending well beyond endopod, with lateral border almost straight, entire, terminating in small mobile spine (Fig. 2F). Endopod 3.3 times as long as wide.
Mouthparts (Fig. 4; dissected from female paratype MNHN-IU-2013-11090). Mandible (Fig. 4 A–C) with reduced cylindrical molar process bearing a few brushes of setae distally (Fig. 4C). Incisor process slightly expanded distally, with four large teeth on truncated tip, of which lateral most enlarged. Palp absent.
Maxillula (Fig. 4D) with slender, feebly bilobed palp, lower lobe bearing a small seta distally. Upper lacinia short and stout, truncate distally, with about 10 robust spines distally. Lower lacinia more slender, with group of long setae on truncate tip.
Maxilla (Fig. 4E) with distally tapering, non-setose palp. Basal endite simple, short, stout and blunt, with simple seta distally. Coxal endite obsolete, medial region slightly convex. Scaphognathite normal, widest centrally, about 2 times as long as broad, with more slender posterior lobe. Marginal plumose setae well developed.
First maxilliped (Fig. 4F) with slender, tapering, non-setose palp. Basal region broad and round, not distinctly separated from coxal region. Median margin straight, sparsely provided with slender setulose setae. Caridean lobe of exopod distinct, with plumose marginal setae; flagellum greatly reduced, devoid of setae, slightly overreaching caridean lobe. Epipod small, somewhat elongate, rounded distally.
Second maxilliped (Fig. 4G) with small dactylar segment, about 1.6 times as long as wide, convex medially, bearing row of stout, serrulate spines. Propodal segment large, twice as long as dactylar segment, twice as long as wide, with subrectangular distomedial angle. Medial margin broadly convex, with row of coarsely serrulate setae. Carpus short. Merus partly fused to ischium, ischium partly fused to basis, basis without exopod; combined segment stout, about twice as long as wide. Coxa produced medially, with small, suboval epipod laterally.
Third maxilliped (Fig. 4H) with broad antepenultimate segment, about 4 times as long as wide. Basis completely fused with ischiomerus, junction indicated medially by small knob; median margin sparsely provided with serrulate setae over proximal two thirds. Penultimate segment slender, about 3 times as long as wide, 0.33 of length of antepenultimate segment and with 2 slender, serrulate setae on medial border. Terminal segment 3 times as long as wide, slightly shorter than penultimate segment, with groups of serrulate setae medially and slender terminal setae. Exopod absent. Coxa not produced medially, with broadly rounded lateral lobe and small reduced arthrobranch laterally.
Other specimens
Females similar to holotype. Dorsal rostrum teeth varying from 4 (smaller specimen, PoCL 1.2 mm, damaged, lost) to 5, lamina shallower in smallest specimens, first pereiopod fingers with 3–4 distal cutting teeth. Single male specimen available (Fig. 5) comparatively smaller and more slender than adult females; rostrum (Fig. 5A) more shallow, bearing 4 dorsal teeth; first male pleopod (Fig. 5 B–C) with endopod almost half length of exopod, enlarged distally, with apex rounded, with 3 short simple setae proximally on medial border and 2 short setae more distally on lateral border; second pleopod (Fig. 5 D–E) with endopod slightly shorter than exopod, with appendix masculina about as long as appendix interna, with two unequal distal serrulate setae and one simple seta subdistally on lateral margin.
Measurements (PoCL, RL; mm)
Ovigerous females: 1.9, 1.8; holotype: 1.5, 1.5. Other females 1.3–1.6, 1.2–1.4 (in female of PoCL 1.6, TL 9.5 mm). Male: 1.1, 1.0. Eggs (with eye spots): 0.54–0.65 × 0.40–0.45.
Colouration (Fig. 10 B–C)
Males largely transparent, with diffuse yellow and white speckles, more dense on cephalothorax. Adult females more heavily coloured. Body generally transparent, faintly speckled with yellow and white colour, with yellow dots on base of the rostrum and on eyestalks, yellow colour more condensed to transverse bands on sides of each basis of antennae, two bands on carapace, and one wide band on each of 1 st to 5 th abdominal segments, all interspaced by faint white dots. Whitish path transversely on the tailfan articulations to the last abdominal segment. Anterior rostrum, antennal flagella, pereiopods, the sixth abdominal segment, and tailfan, predominantly transparent. One female from Papua New Guinea reddish coloured instead of yellow.
Host
Associated with branching soft corals of the genus Nephthea sp. (Fig. 10C) of the family Nephtheidae (Octocorallia: Alcyonacea).
Distribution
Up to date known from the Madang Lagoon, Papua New Guinea, and the Great Barrier Reef, Australia.
Remarks
See the Discussion.
description: Published as part of Horká, Ivona, Fransen, Charles H. J. M. & Ďuriš, Zdeněk, 2016, Two new species of shrimp of the Indo-West Pacific genus Hamodactylus Holthuis, 1952 (Crustacea: Decapoda: Palaemonidae), pp. 1-26 in European Journal of Taxonomy 188 (188) on pages 5-12, DOI: 10.5852/ejt.2016.188, http://zenodo.org/record/3837557