Periclimenaeus nufu, Ďuriš & Horká & Hoc, 2009

Ďuriš, Zdeněk, Horká, Ivona & Hoc, Dao Tan, 2009, Periclimenaeus Nufu, A New Species Of Shrimp (Crustacea: Decapoda: Pontoniinae) From Vietnam, Raffles Bulletin of Zoology 57 (2), pp. 453-464 : 454-460

Periclimenaeus nufu , new species

( Figs. 1–5 )

Material examined. – Holotype: female (CL 1.9 mm, TL 6.5 mm), ION R.4254/E.54104, sample n. 10.D2, Bai Tré site, Lon Island , 12 o 36'25"N, 109 o 19'58"E, Van Phong Bay , Vietnam, South China Sea, 28 Sep.2003, depth 5m, coral rubble, coll. ION staff (Department of Marine Living Resources).

Diagnosis. – Rostral dentition 4/0; anteroventral angle of carapace produced, movable; telson with two pairs of large dorsal spines at 0.2 and 0.5 of telson length, posterior margin with lateral spines situated anteriorly from remaining spines; first abdominal segment tergite with anterior median lobe; mandibular incisor process normal, distally dentate; first pereiopod fingers with cutting edges entire, carpus longer than chela, coxa with distal lobe dorsally and unarmed ventrally; major second pereiopod with dactyl almost semicircular dorsally and with low plunger ventrally, palm looks granulate – covered by numerous soft papillae; minor second pereiopod fingers with cutting edges simple, straight, shear-like fingers shorter than palm, palm papillose; ambulatory dactyli biunguiculate, with slender unguis subequal to corpus length and distoventral tooth feebly developed, ventral margin of corpus concave, denticulate proximally; uropodal rami broadly ovate, distolateral angle of exopod rounded, serrate.

Etymology. – The abbreviation NUFU (Norwegian Program for Development, Research and Education) is adopted as the specific name for the new species, in reference to the Vietnamese-Norwegian research project under which the type specimen was collected and examined.

Description (based on the female holotype). – A small sized pontoniine shrimp of subcylindrical form belonging to the Periclimenaeus robustus species group ( Bruce, 2005) ( Fig. 1 ).

Rostrum ( Fig. 2B ) about 0.35 of CL, reaching distal end of basal segment of antennular peduncle, slightly arched dorsally with four acute teeth, first tooth well in advance of posterior orbital margin, with short interspersed setae, ventral lamina toothless, straight, upturned proximally.

Carapace ( Figs 1 ; 2A,B ) smooth, without epigastric, supraorbital or hepatic spines, with a low swollen tubercle in postorbital position; antennal spine well developed, marginal, inferior orbital angle obsolete, anteroventral margin of carapace produced, rounded, forming soft movable plate.

Abdomen smooth, first segment tergite with low, anteriorly directed and flattened median lobe on dorsal surface ( Fig. 2E ), pleura rounded, fourth and fifth posteriorly produced, rounded, sixth segment median length subequal to fifth segment length, posterolateral and posteroventral angles produced, subacute.

Telson ( Fig. 2F ) about 1.4 times sixth abdominal segment length, 0.5 of CL, 1.7 times longer than anterior width; lateral margins feebly convex, posteriorly convergent; dorsal telson spines about 0.16-0.18 of telson length, situated at 0.2 and 0.5 of telson length; posterior margin broadly convex without median point, lateral posterior spines half of dorsal spines length, situated in advance of intermediate and submedian spines, intermediate spines subequal to dorsal spines, submedian spines 1.3 times longer than intermediate spines, stout, setulose.

Eyes ( Fig. 2A ) with globular cornea situated obliquely on stalk, with small accessory pigmented spot dorsally on stalk close to posterior corneal margin; corneal diameter about 0.2 of postorbital CL; stalk short, swollen, medial length about 1.5 of corneal diameter.

Antennule ( Figs. 2A,C ) of normal form; basal peduncular segment about 2.5 times as long as central width, stylocerite elongate, subtriangular, distally acute and laterally rounded, lateral margin straight, slightly tapering distally, distolateral tooth stout, subtriangular, overreaching anterior margin, reaching almost to distal end of intermediate segment, medial margin with minute ventromedial tooth at about 0.4 of segment length; intermediate segment about 0.2 of proximal segment length, distinctly wider than long, distal segment slightly longer than preceding, length subequal to width; upper flagellum biramous; four proximal segments fused, short ramus with three segments, 6 groups of aesthetascs; longer ramus slender, with about seven segments, lower flagellum similar, slender with about 10 segments.

Antenna ( Fig. 2D ) of normal form; basicerite short, laterally and dorsally unarmed; carpocerite subcylindrical, reaching about 0.75 of scaphocerite length; scaphocerite about 2.5 times longer than broad, broadest at about 0.6 of length, anterior margin rounded, lateral margin slightly concave, almost straight, with well developed distal tooth reaching level of distal margin of lamella.

Thoracic sternites narrow and unarmed.

Mouthparts ( Fig. 3 ) from left side dissected. Mandible ( Fig. 3A,B ) without palp; incisor process well developed, with four apical teeth, molar process tapering distally, with four groups of subacute teeth.

Maxillula ( Fig. 3C ) with bilobed palp ( Fig. 3D ), lower lobe short, with small spinule; upper lacinia broad, dorsal margin convex, distal margin with about eight strong serrate spines and several slender serrulate setae; lower lacinia short, truncate, with a group of about eight slender terminal and four subterminal setae, several long setae on ventral margin.

Maxilla ( Fig. 3F ) with simple palp, tapering, distally rounded, basally setose, slightly shorter than basal endite, basal endite deeply bilobed, upper lobe with about eight slender simple setae and single plumose distal seta, lower lobe slightly more than 3 times longer than central width, anterior lobe about 1.5 times longer than basal width, medial margin slightly angulate proximally, marginal setae plumose; posterior lobe well developed.

First maxilliped ( Fig. 3G ) with elongate flattened palp, about thrice longer than central width, not reaching anterior margin of basal endite, with single preterminal plumose seta; basal endite with distal margin produced, rounded, medial margin straight with numerous slender setulose setae and one single seta; coxal endite divided from basal endite by shallow emargination, with several long setulose setae medially; exopod with normal flagellum with four plumose terminal setae, caridean lobe large; produced, with lateral margin broadly rounded, marginal setae plumose; epipod well developed, deeply bilobed, lobes elongate, distally rounded.

Second maxilliped ( Fig. 3H ) with normally developed endopod, dactylar segment broad, about thrice longer than maximum width, distomedial margin straight, with numerous serrulate spines; propodal segment normal, distomedial margin weakly convex with several simple spines; carpus, merus and ischiobasis without special features; coxa medially angulate with pair of setae; exopod normally developed with four plumose terminal setae; epipod elongate, reaching two-thirds of ischiobasal length, rounded distally, without podobranch.

Third maxilliped ( Fig. 3I ) stout, with endopod slightly overreaching distal end of carpocerite; coxa with minute ventral tubercle, non-setose, lateral plate semicircular, arthrobranch absent; basis fused with ischiomerus, combined ischio-basal segment about 3.5 times longer than basal width, with series of long and short spiniform setae ventrally and pair of short distolateral setae; penultimate segment about 0.45 of ischio-basal segment length, 2.5 times longer than wide, with ventrolateral and ventromedial rows of long spiniform setae and pair of short distolateral setae - one spiniform; terminal segment about 0.6 of penultimate segment length, with pair of terminal spines longer than segment and scattered shorter spiniform setae ventrally and on sides of ventral margin; exopod normally developed, subequal to ischio-basal segment, with four plumose terminal setae.

First pereiopods ( Fig. 4 A-B) stout, overreaching carpocerite by distal end of merus; chela with palm subcylindrical, compressed, 1.7 times longer than deep, fingers similar, subequal to palm length, broad and high basally and tapering distally, with groups of short stiff setae, subspatulate, with elongate unguis and small adjacent tooth distally ( Fig. 4C ), cutting edges medial, entire; carpus 1.2 times chela length, thrice longer than distal width, tapering proximally; merus slightly longer than carpus and 5 times longer than central depth; ischium two thirds of merus length; basis without special features; coxa simple ventrally but dorsally produced to distinct lobe with rounded tip.

Major second pereiopod ( Fig. 4D ) well developed, length about twice CL, palm about twice longer than maximal depth, slightly swollen proximally, oval in section, covered with small soft papillose tubercles ( Fig. 4 ) dorsally and ventrally, ventral tubercles aligned to transversal rows ( Fig. 4F ); fingers ( Fig. 4E ) 0.4 of palm length, sparsely setose; dactyl twice longer than maximal depth, dorsal margin strongly convex, with stout obtuse hooked tip, cutting edge with low elongate molar process proximally, distal cutting edge convex, entire; fixed finger tapering distally, tip hooked; carpus about 0.35 of palm length, narrow proximally, broadly expanded distally, several tubercles ventrally; merus about 0.4 of palm length, robust, twice longer than central depth, tuberculate ventrally; ischium 0.8 of meral length, twice longer than distal depth, tapering proximally, without ventral denticles; basis and coxa normal, without special features.

Minor second pereiopod ( Fig. 4H ) chela length subequal to CL, with palm ( Fig. 4I ) tuberculate dorsally and ventrally, oval in section, 1.5 times longer than central depth, tapering slightly proximally, ventral margin convex; with series of long setae along ventral margin of palm and fixed finger; fingers about two thirds of palm length, dactylus compressed, slightly exceeding fixed finger, about 2.4 times longer than maximal depth, dorsal margin convex, tip blunt, cutting edge simple; fixed finger basal width subequal to dactylus width, rather straight, tapering distally to upturned subacute tip, cutting edge grooved proximally; carpus short, less than 0.4 of palm length, stout, distally excavate, length subequal to distal depth, ventral margin simple; merus short and stout, slightly longer than both carpus length and half of palm length, about 1.7 times longer than central depth, ventral margin tuberculate; ischium subequal to merus length, ventral margin with distomesial rounded lobe; basis and coxa short, robust, without special features.

Ambulatory legs robust; third pereiopods ( Fig. 5A, C ) with dactyli ( Fig. 5B, D ) 0.4 of propod length, feebly biunguiculate; unguis distinctly demarcated, slender, 5 times longer than basal width, slightly curved, corpus compressed, about twice longer than proximal depth, tapering distally, dorsal margin slightly convex, ventral margin sinuate, with minute but acute distal accessory tooth somewhat separated from base of unguis, three minute sharp denticles proximally on corpus; propod about 0.55 of CL, 3.8 times longer than proximal width, tapering distally, distoventral angle armed with two stout spines about 0.5 of dorsal corpus length, three to four additional smaller single spines irregularly spaced on ventral margin, with proximal one smallest and close to preceding spine; carpus subequal and as stout as propod, about 3.5 times longer than distal width, tapering proximally, unarmed; merus subequal to propod length but stouter, about 3 times longer than proximal width, several sharp tubercles ventrally; ischium two thirds of propod length, slightly more slender than merus, tapering proximally; basis and coxa robust, without special features.

Fourth and fifth pereiopods ( Fig. 5E, G , respectively) generally similar and subequal to third pereiopods, with daclyli ( Fig. 5F, H , respectively) gradually slightly slender and longer than third dactylus; fourth dactylus with accessory tooth vestigial, corpus with only single proximal denticle on ventral margin; fourth propodus with distoventral pair of spines short, 0.25 of dactylar corpus dorsal length; fifth dactylus with unguis unusually long, nine times longer than basal width, additional unguis inconspicuous, corpus unarmed; additional ventral spines lacking; fifth propod totally unarmed.

Uropods ( Fig. 2H ) with protopodite posterolaterally unarmed; exopod ( Fig. 2I ) broadly ovate, subequal to telson length, 1.6 times longer than broad, lateral margin convex with distal half serrate, non-setose, distolateral angle produced to rounded serrate lobe, serration with vestigial terminal denticles ( Fig. 2 I-detail), distolateral lobe medially with slender acute spine with incurved tip, spine far exceeding distal end of lobe and reaching level of distal end of exopod; endopod slightly shorter than exopod, ovate, 2.2 times longer than broad.

Color. – Specimen preserved, no traces on color.

Host. – The specimen was collected during an examination of coral rubble. No host animal was recorded. All species of Periclimenaeus , if their host is reported, live in association with host animals, sponges or compound ascidians.

Distribution. – Known only from the type locality, Van Phong Bay, south of Nhatrang Bay, Vietnam (South China Sea).

Figures

Fig. 1. Periclimenaeus nufu, new species, female holotype. Scale bar = 1 mm.

Fig. 2. Periclimenaeus nufu, new species, female holotype. A, anterior cephalothorax, eyes and antennae, dorsal. B, anterior carapace, lateral. C, antennule, dorsal. D, antenna, ventral. E, posterior carapace and anterior first abdominal segment, dorsal. F, telson, dorsal. G, same, distal part. H, right uropod, dorsal. I, same, exopod, with distolateral margin enlarged. Scale bars = 0.5 mm.

Fig. 3. Periclimenaeus nufu, new species, female holotype, mouthparts (from the left side). A, mandible. B, same, molar and incisor processes. C, maxillula. D, same, palp. E, same, laciniae. F, maxilla. G, first maxilliped. H, second maxilliped. I, third maxilliped. Scale bars = 1 mm.

Fig. 4. Periclimenaeus nufu, new species, female holotype. A, right first pereiopod, lateral. B, same, distal segments, lateral. C, same, tips of fingers. D, major second pereiopod, lateral. E, same, distal palm and fingers, mesial. F, same, ventral margin of palm. G, same, tubercle from ventral palm. H, minor second pereiopod, lateral. I, same, chela. Scale bars = 1 mm.

Fig. 5. Periclimenaeus nufu, new species, female holotype. A, left third pereiopod, lateral. B, same, distal propodus and dactylus. C, right third pereiopod, lateral. D, same, distal propodus and dactylus. E, right fourth or fifth pereiopod, lateral. F, same, distal propodus and dactylus. G, left fifth pereiopod, lateral. H, same, distal propodus and dactylus, mesial. Scale bars: A, C, E-G = 1 mm; B, D, F, H = 0.1 mm.