Periclimenaeus heronensis, Bruce, 2010

Bruce, A. J., 2010, More pontoniine shrimps (Crustacea: Decapoda: Palaemonidae) from the CReefs 2009 Heron Island expedition, Zootaxa 2604 (1), pp. 20-36 : 21-29

publication ID	https://doi.org/ 10.11646/zootaxa.2541.1.3
persistent identifier	https://treatment.plazi.org/id/1F1687AB-FFA5-5D33-FF5F-D26D1C260E1C
treatment provided by	Felipe
scientific name	Periclimenaeus heronensis
status	sp. nov.

Treatment

Periclimenaeus heronensis View in CoL sp. nov.

( Figs 1–5 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 )

Material examined. 1 ♂, holotype, dissected, Heron Island reef, north-eastern side, HI09-76A, 23°29.990’S 151°55.601’E, 12m, 22 November 2009, dead Acropora , coll. N.L. Bruce & K. Schnabel, QM W31919 GoogleMaps .

Diagnosis. Rostrum slender, dentition 5/0, reaching to end of antennular peduncle, without supraorbital spines or tubercles, first abdominal tergite without median anterodorsal lobe, scaphocerite with small distolateral tooth, slightly exceeding lamella, incisor process of mandible well developed, simply acutely pointed, first pereiopod slender, chela greater than half carpus length, fingers forcipulate, second pereiopod chelae with palms smooth, major with large molar process, cutting edges entire, merus minutely tuberculate ventrally, minor chela with dactyl elongate, exceeding tip of fixed finger, cutting edge mainly entire, with low tooth proximally covered with minute acute tubercles, fixed finger longitudinally deeply grooved, with rounded tooth proximally, covered with minute acute tubercles; third pereiopod dactyl biunguiculate, corpus entire, without basal armament, propod with paired distoventral and 1 distal ventral spine, telson with dorsal spines well developed, at 0.3 and 0.6 of telson length, uropod with exopod laterally with distal tooth and spine only.

Description. Male. A small sized slender species of typical Periclimenaeus form.

Rostrum ( Fig. 1B View FIGURE 1 ), tip missing, about 0.48 of CL, slender, reaching to end of proximal segment of antennular peduncle, dorsal carina feebly developed, with 5 acute slender teeth, first four of increasing size distally, first tooth anterior to posterior orbital margin, preterminal tooth smaller, teeth separated by long slender simple median setae, ventral margin feebly concave, unarmed, non-setose.

Carapace ( Fig. 1A View FIGURE 1 ) smooth, glabrous, without supraorbital spines or tubercles, post-orbital or hepatic spines, posterior orbital carina feebly developed, continuous with well developed slender marginal antennal spine, inferior orbital angle completely obsolete, pterygostomial angle not produced, obtusely rounded.

Abdominal segments smooth, glabrous, first without median anterior dorsal lobe, third tergite not posteriorly produced, sixth segment about 0.35 of CL, subequal to length of fifth segment length, 1.1 times longer than deep, posterolateral angle acute, posteroventral angle larger, acute, pleura all posteroventrally rounded.

Telson ( Fig. 1G View FIGURE 1 ) 0.77 of CL, about twice as long as anterior width, lateral margins straight, convergent, with 2 pairs of short, subequal dorsal spines, about 0.07 of telson length, at 0.3 and 0.6 of telson length, posterior margin about 0.5 of anterior width, broadly rounded, without median point, lateral posterior spines ( Fig. 1H View FIGURE 1 ) slightly smaller than dorsal spines, intermediate spines well developed, robust, 0.22 of telson length, submedial spines 0.83 of submedial spine length, with sparse simple setae.

Antennule ( Fig. 1C View FIGURE 1 ) with proximal segment of peduncle twice as long as central width, medial margin straight, non-setose, without ventromedial tooth, lateral margin concave, laterally produced proximally, distolateral angle ( Fig. 5A View FIGURE 5 ) without tooth, blunt, stylocerite acute, reaching to 0.4 of segment length, statocyst poorly defined, with granular statolith; intermediate and distal segments subcylindrical, intermediate 0.7 of distal segment length, combined length 0.7 of proximal segment length; upper flagellum ( Fig. 5B View FIGURE 5 ) biramous, upper ramus with 3 proximal segments fused, with 1 free segment, 8 groups of aesthetascs, lower ramus slender, incomplete.

Antenna ( Fig. 1D View FIGURE 1 ) with basicerite laterally unarmed, carpocerite slender, subcylindrical, 6.75 times longer than distal width, extending well beyond scaphocerite; scaphocerite ( Fig. 1E View FIGURE 1 ) about 2.5 times longer than distal width, distally rounded, lateral margin straight with small distolateral tooth at about 0.9 of lateral margin length, reaching to level of anterior margin of lamella, flagellum slender, incomplete.

Eye ( Fig. 1F View FIGURE 1 ) with globular cornea, about 0.2 of CL, well pigmented, without accessory pigment spot, eyestalk about as wide as long.

Ophthalmic somite, epistome, labrum, and paragnath, without special features.

Mandible ( Fig. 2A View FIGURE 2 ) with corpus normal, without palp; incisor process well developed, tapering to single acute distal tooth, medial margin distally concave, otherwise straight; molar process ( Fig. 5 View FIGURE 5 EF) subcylindrical, distally oblique, with small anterior marginal tooth, with similar dorsal marginal tooth and larger posterior tooth, with marginal row of simple setae, anterior margin longitudinally carinate ( Fig. 5C View FIGURE 5 ).

Maxillula ( Fig. 2B View FIGURE 2 ) with palp ( Fig. 5G View FIGURE 5 ) stout, very feebly bilobed, ventral lobe with short sinuous ventral spinule; upper lacinia ( Fig. 5H View FIGURE 5 ) broad, distally transversely truncate, with single row of eight simple marginal spines, fully ankylosed with lacinia, with two slender submarginal spines; lower lacinia bluntly rounded distally, with numerous slender simple spiniform setae.

Maxilla ( Fig. 2C View FIGURE 2 ) with slender tapering palp, with single short plumose seta proximally on lateral margin; basal endite short, broad, distally bilobed, lobes short, rounded with six slender simple setae; coxal endite obsolete, medial margin convex, non-setose; scaphognathite normal, 2.7 times longer than broad, anterior lobe 1.2 times longer than basal width, distally rounded with medial margin feebly concave, posterior lobe half length of anterior lobe.

First maxilliped ( Fig. 2D View FIGURE 2 ) with stout non-setiferous palp, slightly exceeding distal margin of caridean lobe; basal and coxal endites fully fused, basal portion with sparse long feebly setulose setae, medial margin straight, coxal portion convex, with three slender simple marginal setae; exopod well developed, flagellum slender, with four plumose terminal setae, caridean lobe broad, about twice as long as wide; epipod large, cordiform.

Second maxilliped ( Fig. 2E View FIGURE 2 ) of normal form, dactylar segment about 3.2 times longer than distal width, with numerous long slender finely setulose spines along medial margin; propodal segment with disto-medial margin broadly rounded with several slender simple spines; carpus with disto-medial angle acute; merus and ischio-basis without special features, exopod well developed, flagellum slender with four plumose terminal setae; coxa slightly produced medially, non-setose, epipod simple, twice as long as broad, without podobranch

Third maxilliped ( Fig. 2F View FIGURE 2 ) short, robust, reaching to about middle of carpocerite, ischio-merus and basis completely fused, combined segment flattened, about 2.4 times longer than proximal width, tapering slightly distally, lateral margin straight, non-setose, medial margin with coxal portion feebly convex, ischio-meral region feebly concave, both with sparse slender simple setae; carpus about 0.6 of antepenultimate segment length 3.0 times longer than wide, medial margin with numerous long slender finely setulose setae, terminal segment about 0.8 of preterminal segment length, 4.0 times longer than basal width, tapering distally, with numerous long slender densely setulose spines medially, exopod as on second maxilliped; coxa medially excavate, with well developed low rounded lateral plate, without arthrobranch.

Fourth thoracic sternite ( Fig. 4H View FIGURE 4 ) with semicircular perpendicular transverse carina; posterior sternites unarmed.

First pereiopod ( Fig. 4A View FIGURE 4 ) slender, chela ( Fig. 4B View FIGURE 4 ) about 0.5 of CL, palm compressed, twice as long as deep centrally, with small groups of slender cleaning setae proximo-ventrally, fingers slender, tapering strongly distally with small bidentate tips, dactyl about 5.5 times longer than proximal depth, cutting edge lateral, feebly laminar distally, entire, fixed finger similar; carpus 1.1 times chela length, 5.6 times longer than distal width, tapering proximally, with slender cleaning setae distoventrally; merus 1.17 times chela length, 1.05 times carpus length, 5.5 times longer than central width; ischium, 0.95 of chela length, 4.0 times longer than distal width, tapering proximally; basis about 5.5 of chela length; coxa robust, without distoventral process.

Major second pereiopod (left) ( Fig. 3A View FIGURE 3 ) with chela ( Fig. 3B View FIGURE 3 ) massive, 3.0 times CL, palm oval in section, about 2.2 times longer than central depth, very finely granulate ventrally, (virtually invisible but palpable), tapering slightly distally, sparsely setose, fingers ( Fig. 3 View FIGURE 3 CD) about 0.33 of palm length, in-curved, dactyl robust, compressed, about twice as long as deep with strongly convex dorsal margin, tip bluntly hooked, cutting edge with large molar process centrally, distal third concave, blunt, entire, fixed finger about 1.2 times longer than proximal depth, with bluntly hooked tip, cutting edge with well developed fossa on central portion, medial margin with large acute tooth and smaller proximal tooth, lateral margin proximally broadly expanded, feebly convex, distal cutting edge blunt, entire; carpus about 0.28 of palm length, as wide distally as long, tapering strongly proximally, moderately excavate distally, unarmed; merus about 9.4 of palm length, twice as long as central width, slightly bowed and centrally swollen, ventral margin with 10 small denticles; ischium about 0.29 of palm length, 1.8 times longer than distal width, tapering strongly proximally, ventral margin with 6 minute denticles; basis and coxa stout, without special features.

Minor second pereiopod (right) ( Fig. 3D View FIGURE 3 ) chela ( Fig. 3E View FIGURE 3 ) about half of major chela length, 1.5 times CL, palm smooth, oval in section, sparsely setose, 2.75 times longer than proximal depth, tapering slightly distally, dactyl ( Fig. 3 View FIGURE 3 FG) about 0.45 of palm length, extending well beyond tip of fixed finger, 3.75 times longer than basal width, curved, with stout blunt tip, distal half feebly concave, sharp, entire, proximal fourth concave, second fourth cutting edges thickened, covered with minute acute denticles, fixed finger ( Fig. 3 View FIGURE 3 FG) about 0.9 of dactylus length, 2.0 times longer than proximal depth, with small blunt feebly hooked tip, cutting edge deeply longitudinally grooved except near tip, medial margin with low rounded thickening proximally, covered with minute acute denticles ( Fig.3H View FIGURE 3 ), lateral margin similar but at higher level and with larger tuberculate thickening proximally; proximal segments similar to major chela but smaller, ventral margins without denticles.

Third pereiopod ( Fig. 4C View FIGURE 4 ) reaching to about distal end of antennular peduncle; with propod about 0.53 of CL, dactyl ( Fig. 4E View FIGURE 4 ) compressed, biunguiculate, about 0.17 of propod length, unguis short, 0.25 of corpus length, clearly demarcated, 1.4 times longer than basal width, slender, simple, very acute, corpus twice as long as deep, dorsal margin feebly convex, ventral margin with stout, strongly curved terminally blunt distal accessory tooth, larger than unguis, ventral margin feebly convex with 3 small low blunt denticles, with pairs of long simple sensory setae medially and laterally; propod ( Fig. 4D View FIGURE 4 ) 4.4 times longer than deep, sparsely setose, tapering distally, distal width about half of proximal, with 2 robust distoventral spines, lateral spine about 6.5 times longer than basal width, 0.95 of distal propod width, medial spine about 0.55 of lateral spine length, 1 preterminal distal ventral spine, slightly smaller than distal medial spine; carpus subequal to propod length, 3.0 times longer than central width, unarmed; merus about 1.15 times propod length, 3.2 times longer than central width, unarmed; ischium 0.95 of propod length, 2.75 times longer than distal width, unarmed; basis and coxa robust, without special features.

Fourth pereiopod similar to third, propod ( Fig. 4F View FIGURE 4 ) shorter, about 0.9 of third propod length.

Fifth pereiopod generally similar to third and fourth pereiopods, propod ( Fig. 4G View FIGURE 4 ) 1.1 times longer than third propod length, 6.0 times longer than proximal width, with single smaller distoventral spine only, with numerous long setae over distal third of ventral margin.

First pleopod ( Fig. 5I View FIGURE 5 ) with basipodite twice as long as broad; exopod 1.1 times basipodite length, 4.0 times longer than broad; endopod ( Fig. 5J View FIGURE 5 ) 2.43 of exopod length, 3.0 times longer than wide, distally rounded, lateral margin with 6 short plumose setae, medial margin without accessory lobe, with 12 slender simple spiniform setae, decreasing in size proximally.

Second pleopod ( Fig. 5K View FIGURE 5 ) basipodite 2.3 times longer than broad, slightly longer than first basipodite length; exopod 1.1 times basipodite length; endopod 0.9 of exopod length, appendices ( Fig. 5L View FIGURE 5 ) at 0.4 of medial margin length, appendix masculina with corpus greatly reduced, subcylindrical, twice as long as wide, with single long slender simple terminal spine, 4.4 times length of corpus; appendix interna 3.2 times longer than interna corpus, with few cincinnuli.

Uropod ( Fig. 1I View FIGURE 1 ) with protopodite posterolaterally rounded; rami broad, exopod 1.7 times longer than broad, lateral margin feebly convex, sparsely setose, with stout distolateral tooth ( Fig. 5M View FIGURE 5 ) with much longer spine medially; diaeresis obsolete; endopod about 1.2 times exopod length, 2.2 times longer than broad.

Measurements (mms). Post-orbital carapace length, 2.0; carapace and rostrum, 3.4; total body length (approx.), 9.2; major chela, 6.1; minor chela, 3.2.

Colouration. No data.

Etymology. From the locality of collection, Heron Island.

Systematic position. Periclimenaeus heronensis sp. nov. most closely resembles P. matherae Bruce, 2005 . The two species may be separated by the following characters:

Rostral dentition 5/0 in P. heronensis (7/0 in P. matherae ); supraorbital tubercles absent in P. heronensis (present in P. matherae ); inferior orbital angle absent in P. heronensis (present in P. matherae ); strong ventromedial tooth on proximal segment of antennular peduncle absent in P. heronensis (present in P. matherae ); distolateral tooth on proximal segment of antennular peduncle absent in P. heronensis (present in P.matherae ); carpocerite far exceeding scaphocerite in P. heronensis (only slightly in P.matherae ; distolateral spine of scaphocerite at 0.9 of length in P. heronensis , almost reaching level of distal margin of lamella (at 0.68 in P. matherae , falling far short of distal margin of lamella); major second pereiopod dactyl with cutting edge entire in P. heronensis (denticulate in P. matherae ); ambulatory dactyl with short slender acute dactyl, longer curved blunt distal accessory tooth in P. heronensis (much longer unguis in P. matherae , with acute curved accessory tooth); dorsal telson spines small in P. heronensis (larger in P. matherae ). Periclimenaeus matherae is known only from Ashmore Reef, Western Australia.

Host. Unknown, most probably a sponge.

Remarks. Found in same collection with the specimen of P. arthrodactylus (Holthuis, 1952) reported by Bruce (2010). Specimen complete, except lacking right fourth and fifth pereiopods and left uropod.

In the course of identification, Periclimenaeus usitatus Bruce was considered a possibility. This species is known only from the type material collected from 20 m off the island of Unguja , Zanzibar, from an unidentified sponge host, of which only an unillustrated preliminary description is available ( Bruce, 1969). The male allotype, NHM 2010 . 291 ( Fig. 6 View FIGURE 6 ), has been re-examined. A significant character was overlooked in the brief original description. The minor second pereiopod chela ( Fig. 6A View FIGURE 6 ) has the palm smooth, oval in section, about twice as long as deep. The dactyl is about 0.62 of the palm length, curved, about 4.2 times longer than basal width, with a slender curved tip and a concave entire sharp cutting edge. The fixed finger is about 2.3 times longer than basal width, with a stouter curved tip, the cutting edge is distinctly longitudinally grooved, medial margin at a lower level than the lateral and straight and entire. The lateral margin is also straight and armed throughout its length by minute acute uniform triangular denticles ( Fig. 6B View FIGURE 6 ). The allotype lacks the major second pereiopod. The holotype female ( RMNH D.253614) has also been re-examined by Dr Charles Fransen who advises that “Indeed the fixed finger has this minute denticulation on the higher medial edge of the groove. It is not a single row of denticles however, but extends into the groove with obtuse denticles forming a granular longitudinal band. I also checked the major second chela, which has the same structure on the fixed finger.”

This arrangement appears to be without parallel in the genus Periclimenaeus . The third pereiopod has the dactylus ( Fig. 6D View FIGURE 6 ) compressed, about 0.16 of the propod length, twice as long as its basal width with the unguis distinctly demarcated, simple, slender, curved, about 3.0 times longer than the basal width: the corpus tapers distally and is about 4.2 times broader proximally than distally, with a slender perpendicular preterminal accessory tooth, ventral margin feebly concave and unarmed. The propod ( Fig. 6C View FIGURE 6 ) is about 3.75 times longer than proximal width and tapers distally, with 2 short distoventral spines, the longer lateral spine about half the distal propod width, the medial spine slightly shorter, with a similar distal ventral spine, and 3 shorter spines on the proximal half of the ventral margin.