Periclimenes manihine, Bruce, A. J., 2006

Bruce, A. J., 2006, Periclimenes manihine sp. nov., a new pontoniine shrimp of the P. alcocki species group (Crustacea: Decapoda: Palaemonidae), Zootaxa 1309, pp. 45-54 : 46-54

publication ID	https://doi.org/ 10.5281/zenodo.173830
publication LSID	lsid:zoobank.org:pub:9761041F-E651-40AC-9326-028BA524079A
DOI	https://doi.org/10.5281/zenodo.6258628
persistent identifier	https://treatment.plazi.org/id/7B1387D7-FFED-2758-9A4E-4205FACDFDE3
treatment provided by	Plazi
scientific name	Periclimenes manihine
status	sp. nov.

Treatment

Periclimenes manihine View in CoL sp. nov.,

( Figs 1–4 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 )

Periclimenes View in CoL sp. Bruce, 1976: 481.

Diagnosis: Periclimenes alcocki species group, with rostral dentition 1+6–8/1–2, antennal and hepatic spines small, antennal spine one spine length posterior to carapace margin, slightly lower than antennal spine, cornea about 0.17 of CL, fixed fingers of major and minor second pereiopod chela distally deeply bifid, palm tuberculate, major dactyl of major second pereiopod without lateral flange, cutting edge with one robust tooth, one less robust tooth more distally, fixed finger with 2 robust teeth, third pereiopod dactyl biunguiculate, fourth and fifth dactyls without accessory tooth, propod spinulate, telson with 4 pairs small, not minute, dorsolateral spines.

Material examined. 1♂ holotype QM W. 28012; 1♂ paratype, RMNH D.51683; 1 ♂ paratype, R.V. Manihine , Cr. 334, Stn. 4, off Ras Ngomeni, Kenya, 3°01’S 40°22.5’E to 2°59.5’N 40°22.6’E, 245–256 m, Agassiz trawl, 7 October 1971, AJB#1644, coll P. Sandu.

Description. Generally similar ( Fig. 1 View FIGURE 1 ) to P. a l c o c k i (see Bruce, 1991: 302–308, figs 2–5; 1996: 228–230, fig.11b–d), or P. brevirostris (see Bruce, 1991: 322–330, figs 15–20).

Rostrum ( Fig. 2 View FIGURE 2 b) well developed, straight, slightly depressed, reaching to about middle of intermediate or distal antennal segments, about 0.5–0. 6 of CL, slender, with tip slightly upturned, dorsal carina distinct, low, with 6–8 small acute similar evenly distributed teeth, with numerous short interdental setae, ventral margin straight, carina obsolete, with sparse short setae proximally, 1–2 small acute teeth distally.

Carapace ( Fig. 2 View FIGURE 2 a) smooth, glabrous, with small epigastric spine separated from first rostral tooth by larger gap then between first and second dorsal teeth, supraorbital spine absent, inferior orbital angle broadly rounded in dorsal view, antennal spine small, slender, placed well below and not exceeding inferior orbital angle, hepatic spine small, slender, about one spine length posterior to anterior carapace margin, slightly lower than inferior orbital angle level.

Abdominal segments without special features. Third segment tergite not posterodorsally produced; sixth segment about 1.6 times fifth segment length, 1.5 times longer than deep, 0.42 of CL., fourth and fifth pleura bluntly angular.

Telson ( Fig. 2 View FIGURE 2 g) about 0.7 of CL, 3.0 times longer than anterior width lateral margin straight, slightly convergent, with 4 pairs of small similar marginal dorsal spines, about 0.5 of telson length, at 0.25, 0.54, 0.7 and 0.9 of telson length, posterior margin ( Fig. 2 View FIGURE 2 h) angular with small acute median point, about 0.4 of anterior width, lateral spines small, robust, similar to dorsal spines, intermediate spines about 0.15 of telson length, submedian spines short slender, densely plumose, about subequal to lateral spine length, intermediate and submedian spines subventral.

Antennule ( Fig. 2 View FIGURE 2 c) well exceeding rostrum, proximal segment of peduncle about 1.6 times longer than wide, medial margin straight, with small ventromedial tooth at about half length, distolateral angle strongly produced, with well developed distal tooth far exceeding anterior margin of lobe, stylocerite slender, reaching to about 0.8 of medial margin length, with short plumose setae proximally, statocyst normal, without statolith; intermediate segment about 1.3 times wider than long, 0.33 of proximal segment length, lateral margin lamellar with numerous plumose setae, medial margin similarly setose; distal segment 1.4 times longer than wide, 0.5 of proximal segment length; upper flagellum biramous, proximal 10 segments fused, shorter free ramus with 4 segments, with about 24 groups of aesthetascs, shorter free ramus and lower flagellum slender, filiform

Antenna ( Fig. 2 View FIGURE 2 d) with basicerite with well developed acute lateral tooth; ischiocerite and merocerite normal, carpocerite subcylindrical, reaching to about 0.5 of scaphocerite length, flagellum well developed, scaphocerite well exceeding antennal peduncle, about 2.6 times longer than broad, anterior margin broadly rounded, lateral margin straight, with well developed tooth at 0.83 of scaphocerite length, about 0.12 of scaphocerite length.

Eye ( Fig. 2 View FIGURE 2 e) with well developed, pigmented globular cornea, without accessory pigment spot, diameter about 0.16 of CL, slightly wider than stalk, stalk length subequal to corneal diameter,

Thoracic sternites with first sternite narrow, second and third increasingly wide, fourth without median process, fifth with low transverse lateral carinae separated by shallow median notch, sixth to eighth unarmed.

Mouthparts on right side examined, showing no noticeable differences from P. brevirostris . Incisor process of mandible with four acute teeth, second maxilliped epipod more elongated oval. Third maxilliped endopod reaching to distal carpocerite.

First pereiopod ( Fig. 3 View FIGURE 3 a) normal, neither slender or robust, reaching to exceed scaphocerite by length of fingers, with chela ( Fig. 3 View FIGURE 3 b) subcylindrical, compressed, about twice as long as deep, with several transverse groups of short denticulate setae proximoventrally, fingers subequal to palm length, simple, with numerous groups of setae, dactyl with bidentate tip, fixed finger unidentate distally, cutting edges entire; carpus subcylindrical, about 1.2 times chela length, 5.6 times longer than distal width, tapering proximally, unarmed, with numerous long denticulate setae distoventrally; merus about 1.05 times carpus length, 1.2 times chela length, 6.1 times longer than width, unarmed; about 0.55 of merus length, 0.7 of chela length; basis and coxa without special features, coxa with small setose ventral lobe.

Second pereiopods well developed, of slightly unequal lengths, dissimilar.

Major second pereiopod ( Fig. 3 View FIGURE 3 c) exceeding carpocerite by carpus and chela, chela ( Fig. 3 View FIGURE 3 d) about 1.25 times CL, palm subcylindrical, oval in section, about 3.0 times longer than depth, covered with minute acute tubercles, sparsely setose, fingers ( Fig. 3 View FIGURE 3 c, 4a) about 0.6 of palm length, dactylus 3.8 times longer than basal depth, proximally slightly swollen, with several small acute denticles dorsally, distally laminar, dorsal margin convex without lateral flange, ventral surface distally scaphoid, with strongly hooked acute tip, cutting edge distally entire, proximally with large acute tooth separated by small notch from smaller distal tooth, fixed finger robust, slightly swollen, about 2.7 times longer than proximal depth, with numerous small acute tubercles ventrally, with 2 large blunt teeth proximally, distal cutting edge entire, tip swollen, with 2 stout teeth ( Fig. 4 View FIGURE 4 b)), separated by notch receiving tip of dactylus; carpus about 0.3 of palm length, 1.5 times longer than distal width, feebly expanded distally, strongly tapered proximally, ventral surface with acute tubercles; merus ( Fig. 3 View FIGURE 3 f) about 0.55 of palm length, 3.0 times longer than deep, uniform, with numerous acute tubercles ventrally; ischium 1.5 of chela length, 1.15 times merus length, 3.3 times longer than distal width, tapering proximally, ventral margin with several acute tubercles distally; basis about half ischium length, slender, unarmed; coxa robust, without special features.

Minor second pereiopod exceeding carpocerite by 0.5 of carpus and chela, chela ( Fig. 3 View FIGURE 3 g) about 0.95 times CL, palm subcylindrical, oval in section, about 3.3 times longer than depth, covered with minute acute tubercles, tubercles generally with short simple seta adjacent, particularly ventrally, fingers about 0.4 of palm length, dactylus 4.0 times longer than basal depth, dorsal margin convex without lateral flange, ventral surface feebly scaphoid, with hooked acute tip, cutting edge distally entire, proximally with acute tooth, fixed finger similar to dactylus, about 3.0 times longer than proximal depth, with numerous small acute setose tubercles ventrally, with single large acute teeth proximally, distal cutting edge entire, tip with 2 stout teeth ( Fig. 4 View FIGURE 4 c)), separated by notch receiving tip of dactylus; proximal segments generally similar to major second pereiopod, slightly less robust.

Third pereiopod slender, exceeding scaphocerite by half propod length; dactyl ( Fig. 2 View FIGURE 2 f) slender, gently curved, compressed, about 0.18 of propod length, unguis distinctly demarkated, slender, about 4.5 times longer than basal width, 0.53 of corpus length, corpus 2.8 times longer than basal width, slightly tapering distally, dorsal margin convex, ventral margin concave with well developed acute distal accessory tooth, about 0.37 of unguis length, with distolateral pair of sensory setae; propod ( Fig. 4 View FIGURE 4 d)) about 0.7 of CL, about 11.5 times longer than wide, with pair of long slender dorsally finely denticulate distal spines ( Fig. 4 View FIGURE 4 e), length about equal to distal propod width or 0.33 of dactyl length, with similar pair of distal ventral spines, 2 isolated ventral spines; carpus 0.5 of propod length, merus subequal to propod length both unarmed, ischium subequal to carpal length, basis and coxa without special features.

Fourth and fifth pereiopods similar to third, propodal spinulation variable, sparse, with numerous spines broken or missing.

First pleopod ( Fig. 4 View FIGURE 4 f)) basipodite about 2.0 times longer than maximal width; exopod 1.4 times basipodite length, 5.0 times longer than wide; endopod ( Fig. 4 View FIGURE 4 g) 0.5 of exopod length, 3.5 times longer than central width, distally expanded, rounded, with single short plumose seta, medial margin with 5 long slender spiniform setae on proximal quarter, 7 short spinules on second quarter.

Second pleopod ( Fig. 4 View FIGURE 4 h) with basipodite about 1.9 times longer than maximal width, slightly longer than first pleopod basipodite; exopod ( Fig. 4 View FIGURE 4 i) 1.25 times basipodite length, 4.2 times longer than maximal width; endopod about 0.95 of exopod length, 5.5 times longer than width, appendices at 0.33 of medial margin length, appendix masculina ( Fig. 4 View FIGURE 4 i) with corpus subcylindrical, slightly tapering distally, 6.0 times longer than width proximally, with about 20 long slender simple spines over medial, anterior and lateral surfaces; appendix interna slightly exceeding appendix masculina, with dense group of cincinnuli distomedially.

Uropod ( Fig. 2 View FIGURE 2 i) normal; protopodite posterolaterally unarmed; rami slightly exceeding telson; exopod 2.6 times longer than width, with lateral margin feebly convex, unarmed, with small acute distolateral tooth with larger mobile spine medially ( Fig. 2 View FIGURE 2 j); endopod about 0.95 of exopod length, 3.0 times longer than wide.

Measurements (mms): Holotype: postorbital carapace length, 3.8; carapace and rostrum, 6.0; total body length (approx.), 16.0; major second pereiopod chela, 5.0; minor second pereiopod chela, 3.7.

HabitatHost: Substrate muddy. Host unknown.

Colouration General body colouration mainly whitish, pinkish laterally; rostrum, gastric and cardiac regions dense white, large white dorsal patches on second and third abdominal tergites, dorsal fourth and fifth tergites and whole caudal fan white; branchiostegite, part of dorsal carapace, dorsal first abdominal tergite, posterior second and third tergites, and pleura, except posterior part of fifth segment pleuron, all pale whitish, finely speckled with minute red chromatophores; proximal segment of antennular peduncle, scaphocerite, second pereiopod carpus and chela all heavily speckled with white; first pereiopod, third to fifth pereiopods translucent whitish with bases and coxae pink; second pereiopod with fingers red, with posterolateral red patch on palm, merus and ischium pinkish, pleopods pink.

Etymology: Named in memory of the former East African Marine Fisheries Research Organization’s vessel, the R.V. Manihine (Goole, Yorkshire, U.K., 1906 — Dar es Salaam, Tanzania, 1992–97 (Jim Porter, pers. comm., 231206),.originally a steel steam sidetrawler named the Coot, and, during the Second World War, a twin diesel engined Admiral’s barge.

Systematic position: A member of the Periclimenes alcocki species group, most closely related to P. brevirostris Bruce, 1991 , sharing the following major characters: Rostrum distinctly shorter than antennular peduncle, with epigastric tooth, cornea well developed, ambulatory dactyls with short simple accessory teeth, telson with four pairs of dorsal spines

Periclimenes manihine differs from P. brevirostris in having the rostrum less strongly tapering, dentition 1+6–8/1–2, (rather than 1+5–6/2), with 1–2 clearly postorbital rostral teeth, hepatic spine closer to anterior carapace margin, first pereiopod with carpus distinctly longer than chela, the fixed finger of both second pereiopods strongly bifid distally and the ambulatory propods having the distoventral and adjacent spines finely denticulate dorsally. The strongly bifid tip to the second pereiopod fixed fingers is the most characteristic feature not shared by any other species of the genus Periclimenes .

Distribution: Known only in the type locality only.

Remarks Periclimenes alcocki was described by Kemp (1922), the first species of a species group now containing 6 species (P. a l c o c k i Kemp, 1922; P. poupini Bruce, 1990 ; P. aleator Bruce, 1991 ; P. brevirostris Bruce, 1991 ; P. albatrossae Chace and Bruce, 1993 ; P. tangeroa Bruce, 2005 ).

They are all relatively poorly known from few specimens, several only from the type material, and occur in deep water, mainly from 300– 600m. Periclimenes manihine represents the shallowest depth at which this group has so far been found. Little is known of their biology, but P. alcocki has been reported in association with a pennatulid, Virgularia sp. ( Bruce, 1996) and P. poupini is associated with pagurids of the genus Trizopagurus associated with actinarians of the genus ( Bruce, 1990). Only one species is so far previously known from the Indian Ocean, P. alcocki s.str., from the Laccadive Sea. The specimen referred to P. a l c o c k i by Bruce (1978) is not that species and represents a related, still not fully described species. The group has otherwise not yet been found outside the West Pacific region.

A key to the species of the Periclimenes including the alcocki species group has been provided by Bruce (1991). This key can be modified to include Periclimenes manihine sp. nov. by the addition of the following couplet.

33. Rostrum distinctly exceeding antennular peduncle, R. 1+5–9/4. P. a l e a t o r Bruce, 1991 Rostrum distinctly shorter than antennular peduncle................................................ 33a 33a.Rostrum markedly tapering distally, without postorbital rostral teeth, first pereiopod carpus short, distinctly shorter than chela and merus, fixed finger of major second pereiopod feebly bidentate; R. 1+5–6/2 ............................... P. brevirostris Bruce, 1991 Rostrum not strongly tapering distally, with 1–2 postorbital rostral teeth, first pereiopod carpus long, distinctly longer than chela, subequal to merus, fixed fingers of both second pereiopods deeply bidentate distally; R. 1+6–8/1–2 ........... P. manihine sp. nov.