Periclimenes tangeroa, Bruce, A. J., 2005

Bruce, A. J., 2005, Pontoniine shrimps from the 2003 NORFANZ Expedition, 10 May – 16 June (Crustacea: Decapoda: Palaemonidae), Zootaxa 981, pp. 1-20 : 12-18

Periclimenes tangeroa sp.nov.

( Figs. 5­7 , 8 D)

Diagnosis: Rostrum slightly exceeding antennular peduncle, with deep lamina, dentition 1+7/1; carapace and abdomen smooth; third abdominal tergite posterodorsally entire, fourth thoracic sternite without median process; distolateral tooth of scaphocerite robust, not exceeding lamella; cornea of eye small; minor second pereiopod with chela surface finely granular, dactylus non­spatulate, merus with small acute tubercles ventrally; third pereiopod with dactyl minutely biunguiculate, propod with three minute ventral. spines; telson with four pairs of dorsal spines, posterior spines reduced.

Material examined: 1 ovig. Ψ, NORFANZ stn. 006/010, South Norfolk Ridge, 34°09.14’S 171°27.95’E, 242­254 m, Sherman sledge, 12 May 2003, NMNZ CR. 9997.

Description: A large species of Periclimenes , of robust subcylindrical body form. The single specimen lacks the major second pereiopod and one third pereiopod.

Rostrum ( Fig. 5 C) well developed, extending slightly beyond antennular peduncle, horizontal, about 0.6 of CL, feebly up­turned distally, dorsal carina well developed, with seven small acute teeth evenly distributed along whole length, with feeble interdental setation, tip acute (Fig. 6A), ventral carina well developed distally, non­setose with single small acute tooth at about 0.6 of rostral length, distoventral margin sinuous, with minute obsolescent denticle.

Carapace ( Fig. 5 A) smooth, glabrous, with stout epigastric tooth at 0.25 of CL, supra orbital spines absent, antennal spine small, marginal, not exceeding inferior orbital angle ( Fig. 5 B), hepatic spine well developed, in advance of level of epigastric tooth, larger than antennal spine, at more ventral level, tip not reaching anterior margin of branchiostegite, anterolateral angle slightly produced, rounded.

Abdomen smooth, glabrous, third tergite not posterodorsally produced, posterior margin entire, pleura of first to fifth segments broadly rounded ( Fig. 5 G), sixth segment about 1.8 times as long as fifth, 0.4 of CL, 1.4 times longer than deep, posterolateral angle and posteroventral angles well developed, subequal, acute.

Telson ( Fig. 5 H) about 0.73 of CL, 3.75 times longer than anterior width, lateral margins almost straight, posteriorly convergent, with four pairs of small marginal spines at about 0.45, 0.63, 0.77 and 0.95 of telson length, spines about 0.04 of telson length, posterior margin ( Fig. 5 I) rounded, without median point, 0.33 of anterior width, posterior spines reduced, lateral spines about subequal to dorsal spines (?, one missing, one broken), intermediate spines 2.1 times dorsal spine length, 0.07 of telson length, submedian spines short, non­setulose, slightly shorter than dorsal spines.

Antennule ( Fig. 5 D) with proximal segment of peduncle about 1.7 times longer than wide, medial and lateral margins subparallel, medial margin with well developed ventral tooth at about 0.5 of length, distolateral angle strongly produced, convex with six plumose setae, with slender acute distolateral tooth reaching to level of proximal border of distal peduncular segment, stylocerite slender, acute, reaching to 0.7 0f segment length, statocyst normal, statolith granular; intermediate segment very obliquely articulated with distal segment, distomedial and distolateral margins with numerous plumose setae, dorsal length about 0.2 of proximal segment length; distal segment dorsal length about 1.5 times intermediate segment dorsal length; upper flagellum biramous, proximal 14 segments fused, shorter free ramus with 6 segments, with about 35 groups of aesthetascs, lower flagellum slender, with numerous segments.

Antenna ( Fig. 5 E) with basicerite with stout distolateral tooth, coxal segment with rounded antennal gland protuberance; carpocerite short, robust, about 1.6 times longer than wide, reaching to about 0.5 of scaphocerite length, flagellum well developed; scaphocerite well developed, well exceeding tip of rostrum, broad, about 2.3 times longer than central width, lateral margin stout, feebly convex, with strong acute distolateral tooth, about 0.1 of lateral margin length, slightly exceeded by broadly rounded distal margin of lamella.

Eye ( Fig. 5 F) with cornea well developed, small, globular, well pigmented, without accessory pigment spot, diameter about 0.1 of CL slightly oblique; stalk subcylindrical, width subequal to length, 0.9 of corneal diameter.

Ophthalmic somite small, without bec ocellaire, with accessory pigment spot.

Epistome unarmed.

The mouthparts on the right side have been examined in detail and appear indistinguishable from those illustrated for P. a l c o c k i by Bruce (1991, fig. 4a­k).

Thoracic sternites without median process on fourth thoracic segment, fifth with low transverse ridge, with median notch, sixth similar to fifth, slightly larger, seventh to ninth broad, unarmed.

First pereiopod (Fig. 6B) slender, exceeding carpocerite by half carpus and chela; chela (Fig. 6C) with palm oval in section, about 2.5 times longer than deep, with sparse short cleaning setae proximoventrally; fingers about 0.7 of palm length, slender, dactylus about 4.6 times longer than basal depth, tapering to small simple acute hooked tip, cutting edge laminar, entire; fixed finger similar; carpus about 1.4 times chela length, 6.3 times longer than distal width, tapering proximally, with few distoventral cleaning setae; merus slightly longer than carpus, slightly bowed, about 8.0 times longer than wide, uniform; ischium 0.55 of carpus length; basis 0.5 of ischium length.

Minor second pereiopod (Fig. 6D) with chela (Fig. 6E) minutely tuberculate, subequal to CL, palm oval in section, subcylindrical, about 4.0 times longer than distal width, slightly tapered proximally; fingers (Fig. 6F) about 0.95 of palm length, sparsely setose, dactylus about 4.7 times longer than proximal depth, tapering distally to acute hooked tip, distal two thirds of cutting edge sharp, entire, proximal third with small acute distal tooth and larger more irregular proximal tooth; fixed finger similar to dactyl, distal tooth larger than proximal tooth; carpus about 0.38 of palm length, slightly excavate distally, tapered Periclimenes tangeroa sp. nov., ovigerous female holotype. A, rostrum, distal end. B, first pereiopod. C, same, chela. D, second pereiopod. E, same, chela. F, same, fingers. G, third pereiopod. H, same, propod and dactyl. I, same, distal propod and dactyl.

strongly proximally, unarmed, feebly denticulate ventrally; merus about 0.7 of palm length, 4.0 times longer than deep, uniform, unarmed, ventral margin coarsely denticulate; ischium subequal to meral length, about 3.7 times longer than distal width, tapering slightly proximally, ventral margin non­denticulate; basis robust, about 0.4 of ischial length, without special features; coxa with small distoventral lobe.

Third pereiopod (Fig. 6G) with dactyl (Fig. 6I), slender, curved, very acute, minutely biunguiculate, 0.28 of propod length; unguis feebly demarkated from corpus, curved, about 5.5 times longer than basal width ( Fig. 7 A), corpus 2.1 times longer than basal width, dorsal margin convex, ventral margin concave with minute acute distal accessory tooth ( Fig. 7 B), about 0.07 of unguis length, with medial and lateral distal sensory setae; propod (Fig. 6H) about 0.5 of CL, 8.2 times longer than proximal depth, tapering very slightly distally, with 3 minute ventral spines at 0.35, 0.68 and 0.92, without visible distoventral spine (possibly lost in dissection), with small groups of simple setae distally; carpus 0.57 of propod length, with well developed distodorsal lobe, unarmed; ischium 1.1 times propod length, 9.5 times longer than width, uniform, unarmed; ischium, basis and coxa without special feature. Fourth and fifth pereiopods similar.

Uropod ( Fig. 5 J) with protopod unarmed, distolaterally rounded, rami reaching to level of distal end of telson; exopod about 2.2 times longer than wide, lateral margin entire, feebly convex, with small distolateral lobe with very small acute tooth (Fig. 6I), with larger mobile spine medially; endopod slightly shorter than exopod, about 2.8 times longer than width.

Ova: Numerous and small.

Measurements: CL 10.2 mm; carapace and rostrum, 15.4 mm; total body length (approx.), 42 mm; second pereiopod, chela, 10.0 mm; ova length, 0.55 mm.

Colouration ( Fig. 8 D): (From colour photo) Body and antennae whitish, rostrum pale red, pereiopods with merus and ischium reddish, carpus dull bluish, minor second pereiopod chela dull reddish banded with dull blue, ambulatory propods white, uropods reddish, lateral exopod white.

Host: No data.

Etymology. The species is named after the NIWA research vessel, the R.V. Tangeroa .

Systematic position: Only five Periclimenes species with four pairs of dorsal telson spines are known: P. a l c o c k i Kemp, 1922, P. a l e a t o r Bruce, 1991, P. brevirostris Bruce 1991 , P. platyrhynchus Bruce 1991 and P. poupini Bruce, 1992 . Periclimenes tangeroa is most closely related to P. alcocki . It may be distinguished by the following features:

1 Dorsal carina of rostrum with seven teeth, ventral carina with single distinct tooth only, vs 8­11 and 2­4.

2 Rostrum without post orbital teeth vs with one postorbital tooth

3 Hepatic spine in advance of level of epigastric tooth, vs at same level.

4 Corneal diameter about 0.1 of CL, vs about 0.75.

5 Third pereiopod dactyl slender, minutely biunguiculate, about 0.28 of propod length, corpus tapering strongly distally; propod with minute distoventral and two similar ventral spines ( Fig. 7 B), vs more robust, with larger accessory tooth, about 0.17 of propod length, corpus tapering feebly distally, and propod without ventral spines ( Fig. 7 C).

Remarks: The holotype specimen of P. a l c o c k i was collected from the Laccadive Sea at 9°34’57”N 75°36’30:E, at a depth of 750 m, and is held in the collections of the Zoological Survey of India (registration number ZSI 4789/7). No additional specimens were collected. Kemp’s description and illustrations clearly show the differences from P. tangeroa with the exception of the ambulatory dactyl, which was not illustrated and, in the description, described “as in P. laccadivensis ”. The figure for P. laccadivensis shows a small slender but well developed dactylar accessory tooth ( Kemp, 1922, fig. 20c). Attempts to obtain further information have not been successful. Bruce (1996) referred a population of 90 specimens from the Arafura Sea to P. a l c o c k i and commented upon their remarkable morphological uniformity. The ambulatory dactyl of similar specimens was illustrated by Bruce (1991, fig. 5h) and shows a small but stout accessory tooth. This identification should possibly be regarded as provisional, pending re­examination of the holotype, as the hepatic spine in the holotype is directly below the epigastric tooth in the holotype, whereas it is markedly in advance in the New Caledonian specimens. Kemp’s description states that the rostrum bears on its dorsal carina “….. 9 teeth, three posterior teeth stand on the carapace behind the orbit”. From his Fig. 21, it appears to show an epigastric tooth and one posterior rostral tooth. It is assumed that the preserved second pereiopod of the present specimen is the minor second pereiopod. Kemp states that in his specimen of P. alcocki the second pereiopods unequal but the “longer limb the dactylus is conspicuously spatulate” and “The smaller chela is similar”. This dactylus in P. tangeroa is non­spatulate.

Figures

FIGURE 5. Periclimenes tangeroa sp. nov., ovigerous female holotype. A, carapace and antennae, dorsal. B, anterior carapace and left antennae, dorsal. C, rostrum. D, antennular peduncle. E, antenna. F, posterior abdominal segments, lateral. G, telson. H, same, posterior spines. I, uropod.

FIGURE 7. Periclimenes tangeroa sp. nov., ovigerous female holotype. A, third pereiopod dactyl, distal corpus and unguis. Third pereiopod dactyls, not to scale, adjusted to same basal depth. B, Periclimenes tangeroa sp. nov. C, Periclimenes alcocki Kemp (redrawn from Bruce, 1996). A, scale bar 0.2 mm.

FIGURE 8. A, Apopontonia disparostris Bruce, NORFANZ stn. 20. B, Hamiger novaezealandiae Borradaile, NORFANZ stn. 133, male. C, Periclimenes fenneri sp. nov., holotype, NOR­ FANZ stn. 154. D, Periclimenes tangeroa sp. nov., holotype, NORFANZ stn. 0 0 6. Scale bars in millemeters.