Periclimenaeus pectinidactylus Uriš, Horká & Sandford, 2009, n. sp.
Creators: name: Uriš, Zden Ě K Ď
name: Horká, Ivona
name: Sandford, Floyd
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Palaemonidae
Periclimenaeus
Periclimenaeus pectinidactylus

description: Periclimenaeus pectinidactylus n. sp.
(Figs 1–5)
Type material. — Holotype: female, CL 1.5 mm, RMNH D 53103; off Southwater Caye, Belizean Barrier Reef, SE off Dangriga, Belize, Caribbean Sea, 12 vi 2006, scuba, reef slope, 16.4 m, from an unidentified sponge (Smenospongia sp.?) # S25, coll. Z. Ď uriš & E. Vásquez.
Diagnosis. — Rostral dentition 6/0; first abdominal segment tergite without anterior median lobe; mandibular incisor process strongly reduced, toothless; antennal carpocerite short, not reaching half length of scaphocerite; first pereiopod fingers with cutting edges denticulate on medial margin, carpus shorter than chela; minor second pereiopod fingers with cutting edges simple, fingers shorter than palm; ambulatory dactyli biunguiculate, ventral margin of corpus concave, simple, without basal process.
Description (based on female holotype). — A small sized pontoniine shrimp of subcylindrical form lacking the major second pereiopod (Fig. 1).
Rostrum (Fig. 2 A) with distinct midrib, about 0.5 of CL, not reaching distal end of basal segment of antennular peduncle, slightly arched dorsally with six acute, anteriorly diminishing, teeth on distal 0.7 of rostral length, with short setae interspersed proximally, ventral lamina with margin without teeth, straight, upturned proximally.
Carapace (Figs 1; 2A) smooth, without epigastric, supraorbital or hepatic spines; antennal spine well developed, marginal, inferior orbital angle obsolete, anterolateral margin of branchiostegite rounded. Abdomen glabrous, first segment tergite without anterior median lobe, third segment tergite (Fig. 2 C) with posterior margin finely denticulate (visible only under high magnification); pleura rounded, fourth and fifth posteriorly produced, rounded, sixth segment median length greater than fifth segment length, posterolateral and posteroventral angles well developed, acute.
Telson (Fig. 2 D) about 1.4 times sixth segment median length, 0.65 of CL, 2.4 times longer than anterior width; lateral margins feebly convex, posteriorly convergent; dorsal telson spines about 0.12 of telson length, at 0.4 and 0.6 of telson length; posterior margin broadly convex without median point, lateral posterior spines similar to dorsal spines, intermediate spines well developed, slender, about 0.25 of telson length and almost three times lateral spine length, submedian spines almost twice lateral spine length, slender, setulose.
Eyes (Fig. 2 B) with globular cornea situated obliquely on stalks, with small accessory pigmented spot dorsomedially on cornea close to their posterior margin; corneal diameter about 0.3 of postorbital CL; stalk short, medial length subequal to corneal diameter.
Antennule (Fig. 2 B) of normal form; basal peduncular segment about twice as long as central width, stylocerite broad, distally acute, laterally rounded, lateral margin slightly concave, proximally broadly rounded, distally tapering, distolateral tooth well developed, overreaching anterior margin, medial margin with minute ventromedial tooth at about 0.25 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; 3–4 proximal segments fused, short ramus with 1–2 segments, 5 groups of long aesthetascs; longer ramus slender, with about 13 segments, lower flagellum similar, slender with about 13 segments.
Antenna (Fig. 2 E) of normal form; basicerite short, laterally and dorsally unarmed; carpocerite subcylindrical, short, reaching about 0.35 of scaphocerite length; scaphocerite (Fig. 2 E) about 2.5 times longer than broad, greatest at about 0.5 of length, anterior margin rounded, lateral margin slightly concave, almost straight, with well developed distal tooth not reaching level of distal margin of lamella.
Thoracic sternites narrow and unarmed.
Mouthparts (Fig. 3) from left side dissected. Mandible (Fig. 3 A) without palp; incisor process (Fig. 3 B) reduced to short hemispherical lobe (right mandible with similarly reduced incisor process), with minute apical tubercle; molar process (Fig. 3 B) slender, subcylindrical, truncate distally, with two subacute teeth posteriorly and with dense brushes of short setae.
Maxillula (Fig. 3 C) with bilobed palp (Fig. 3 D), lower lobe short, with small spinule; upper lacinia moderately broad, dorsal margin convex, distal margin with about 8 strong spines and several slender spiniform setae; lower lacinia elongate, overreaching upper lacinia, tapering distally, with dense group of slender terminal and subterminal setae, several long setae on ventral margin.
Maxilla (Fig. 3 E) with simple non-setose palp, tapering, distally rounded, of similar length to basal endite, basal endite deeply bilobed, upper lobe with about 6 slender simple distal setae, lower lobe slightly shorter, with about 6 distal setae, coxal endite obsolete, non-setose; scaphognathite normal, almost 3 times longer than central width, anterior lobe about 1.4 times longer than basal width, medial margin convex, marginal plumose setae short; posterior lobe well developed.
First maxilliped (Fig. 3 F) with elongate flattened palp, about 7 times longer than central width, exceeding anterior margin of basal endite, with single preterminal plumose seta; basal endite with distal margin produced, rounded, medial margin straight with numerous spiniform setae and single terminal setulose seta; coxal endite divided from basal endite by shallow but distinct emargination, with several spiniform and two 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. 3 G) with normally developed endopod, dactylar segment broadly subtriangular, about twice longer than maximum width, medial margin straight, with numerous serrulate spines; propodal segment normal, distomedial margin produced, with several serrulate spines; carpus, merus and ischiobasis without special features, merus feebly divided from ischium; coxa medially rounded; exopod normally developed with four plumose terminal setae; epipod (broken in dissection) small, elongate, rounded distally, without podobranch.
Third maxilliped (Figs 3 H, I) with endopod reaching to end of carpocerite; coxa distoventrally produced, with two apical setae, lateral plate rounded, arthrobranch absent; basis with ventral margin rounded, with some spiniform setae, ischiomerus fused to basis, with suture feebly developed, distally recurved (Fig. 3 I), about 3.3 times longer than central width, sparsely setose proximally, with row of six ventromedial long spiniform setae and single small distolateral spine near dorsal margin; penultimate segment about 0.8 of ischiomerus length, 4 times longer than wide, with ventrolateral and ventromedial rows of long spiniform setae; terminal segment about 0.6 of penultimate segment length, tapering distally, with strong terminal spines and scattered spiniform setae ventrally and on sides of ventral margin; exopod normally developed, slightly overreached ischiomerus, with four plumose terminal setae.
First pereiopods (Figs. 4 A-D, 5B, C) (left one dried for scanning electron microscopy – Fig.5 C) stout, overreaching carpocerite by distal end of merus; chela with palm subcylindrical, compressed, 1.5 times longer than deep, fingers similar, subequal, slightly shorter than palm length, broad and high basally and tapering distally, with groups of short stiff setae, subspatulate, with small unguis and smaller adjacent tooth distally, cutting edges distally laminar, medial edge narrow, entire, lateral edge with row of about 40 fine, long denticles with rounded tips (Figs 4 D; 5C) (visible only under high magnification); carpus 1.25 times chela length, 3 times longer than distal width, tapering proximally; merus about 1.3 times carpus length, 4.5 times longer than maximal width at about half length; ischium about 0.5 of merus length; basis ventrally produced to rounded distal and proximal lobes; ischium and basis with ventral lobes bearing rows of long spiniform setae; coxa distoventrally produced to narrow lobe with two short spiniform setae.
Second pereiopod: only minor pereiopod present (Fig. 4 E), damaged by dissection; chela (Fig. 4 F) subequal to CL, with palm smooth, oval in section, 2.6 times longer than maximal depth distally, tapering slightly proximally, with several short setae, ventral margin slightly concave; several long setae along ventral margin of palm and fixed finger, one long seta distomedially on palm reaching to 0.7 of fingers length; fingers about 0.75 of palm length, dactylus compressed, not exceeding fixed finger, about 3.5 times longer than maximal depth, dorsal margin convex, tip hooked, blunt, cutting edge simple; fixed finger basal width subequal to dactylus, 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 about 1.3 of distal depth, non-spinulate; merus subequal to palm length, about 4 times longer than central depth, ventral margin unarmed; ischium 0.7 of meral length, ventrally unarmed; basis and coxa short, robust, basis ventrally rounded, coxa with small ventral tubercle.
Ambulatory pereiopods robust; third pereiopod (Fig. 4 G) with dactyl (Fig. 4 H) 0.28 of propod length, biunguiculate; unguis distinctly demarcated, 3 times longer than basal width, slightly curved, un-ornamented, corpus compressed, about 2.2 times longer than depth, uniformly deep, dorsal margin convex, ventral margin concave, unarmed, with acute distal accessory tooth reaching about 0.3 of unguis, accessory tooth slightly divergent and widely separated from unguis, emargination rounded; propod about 0.55 of CL, 7.3 times longer than rather uniform width, distoventral angle armed with two stout spines, about 0.5 of dorsal corpus length, four additional smaller single spines regularly spaced on ventral margin and vestigial fifth one proximally and more close to preceding spine; carpus stouter than propod, 4 times longer than proximal width, 6.2 times propod length, tapering proximally, unarmed; merus 1.15 times longer than propodus, about 6.5 times longer than wide, uniform, unarmed; ischium 0.7 of propod length, width subequal to merus width, tapering proximally; basis and coxa robust, without special features. Fourth and fifth pereiopods similar, subequal.
Uropods (Fig. 2 D) with protopodite posterolaterally unarmed; exopod 1.2 of telson length, 2.4 times longer than broad, lateral margin convex, unarmed, non-setose, with acute tooth distally and adjacent straight spine about 1.5 times longer than tooth; endopod slightly shorter than exopod, 1.7 times longer than broad.
Measurements (mm). — Post-orbital carapace length 1.5; total length 6.1; rostrum length 0.8.
Color (shrimp freshly dead, in alcohol).—Body orange, coloured covered by red dots.
Host. — Unidentified sponge (Fig. 5 A) (size 14 x 12 x 15 cm, subspherical, compact, surface texture irregularly grooved or tuberculate, dark brown with yellowish niches; tissues toughly elastic, difficult to tear) collected from a depth of 16.4 m on a reef slope. The sponge could be a Smenospongia (Demospongia: Thorectidae), possibly S. conulosa Pulitzer –Finali, 1986 (S. Zea, pers. comm.).
Associated fauna. — One specimen of the alpheid shrimp Synalpheus townsendi Coutière, 1909, and one specimen of pontoniine shrimp Periclimenes sp. from the ‘ iridescens ’–group, were found dead inside the ziplocked plastic bag with which the sponge was covered in-situ, and which was closed immediately after detaching the sponge from the bottom. The former species is a sponge-associate and lives inside sponge; the latter specimen was more likely to have been on its surface ohave been on its surface.
description: Published as part of Uriš, Zden Ě K Ď, Horká, Ivona & Sandford, Floyd, 2009, Periclimenaeus pectinidactylus n. sp. (Crustacea: Decapoda: Pontoniinae) from the Belizean Barrier Reef, Caribbean Sea, pp. 31-40 in Zootaxa 2130 on pages 32-38, DOI: 10.5281/zenodo.188350