Periclimenaeus creefi, 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 : 29-35

publication ID	https://doi.org/ 10.11646/zootaxa.2541.1.3
DOI	https://doi.org/10.5281/zenodo.5309781
persistent identifier	https://treatment.plazi.org/id/1F1687AB-FFAD-5D35-FF5F-D3951BC60AEE
treatment provided by	Felipe
scientific name	Periclimenaeus creefi
status	sp. nov.

Treatment

Periclimenaeus creefi View in CoL sp. nov.

( Figs 7–11 View FIGURE 7 View FIGURE 8 View FIGURE 9 View FIGURE 10 View FIGURE 11 )

Material examined. 1 ov. ♀, dissected, Heron Island reef, north-eastern side, stn HI09-076C, 23°25.990’S 151°55.601’E, 10m, 22 November 2009, dead coral heads, coll. N.L. Bruce & K. Schnabel, QM W31437 GoogleMaps .

Diagnosis. Rostral dentition 5/0, supraorbital spines or tubercles absent, scaphocerite with small distolateral tooth, subequal to lamella margin, major second pereiopod chela smooth, dactyl with finely denticulate cutting edge distally, ambulatory dactyl biunguiculate with acute basal tooth.

Description. Ovigerous female. A small sized slender species of typical Periclimenes form.

Rostrum ( Fig. 7B View FIGURE 7 ) extending to end of intermediate segment of antennular peduncle, slender acute straight slightly depressed, about 0.46 of CL, dorsal carina with 5 well developed acute teeth, all anterior to the orbital margin, with numerous long plumose interdental setae, ventral margin feebly convex, unarmed, non-setose.

Carapace ( Fig. 7A View FIGURE 7 ) smooth, glabrous, without supraorbital spines or tubercles, without distinct postorbital carina, inferior orbital angle obsolete, antennal spine well developed, marginal, paraorbital, pterygostomial angle not produced, obtusely rounded.

Abdominal segments normal, sixth segment 1.05 times fifth segment length, 1.5 times longer than deep, posterolateral angle small, acute, posteroventral angle large, acute, pleura broadly rounded.

Telson ( Fig. 7H View FIGURE 7 ) about 0.66 of CL, 2.2 times longer than anterior width, lateral margins posteriorly convergent, posterior margin 0.5 of anterior width, rounded, without median point, with 2 pairs of well developed similar dorsal spines, 0.12 of telson length, at 0.25 and 0.57 of telson length, lateral posterior spines ( Fig. 7I View FIGURE 7 ) about 0.5 of dorsal spine length, sub-ventral, intermediate spines well developed, robust, 0.2 of telson length, submedian spines setulose, 0.95 of submedial spine length.

Antennule ( Fig. 7C View FIGURE 7 ) with proximal segment of peduncle twice as long as central width, medial margin straight, non-setose, with robust ventromedial tooth ( Fig. 7D View FIGURE 7 ), lateral margin concave, laterally produced, distolateral angle ( Fig. 11A View FIGURE 11 ) with small acute tooth, stylocerite acute, reaching to 0.45 of segment length, statocyst distinct, 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 biramous, upper ramus with 5 proximal segments fused, with 1 free segment, about 12 groups of aesthetascs, lower ramus slender, with 19 segments.

Antenna ( Fig. 7E View FIGURE 7 ) with basicerite laterally unarmed, carpocerite slender, subcylindrical, 5.6 times longer than distal width, extending well beyond scaphocerite; scaphocerite ( Fig. 7F View FIGURE 7 ) reaching to end of antennular peduncle, about 2.5 times longer than distal width, distally rounded, lateral margin straight with small distolateral tooth at about 0.85 of lateral margin length, not reaching to level of anterior margin of lamella, flagella incomplete

Eye ( Fig. 7G View FIGURE 7 ) with globular cornea, about 0.16 of CL, well pigmented, without accessory pigment spot, eyestalk about 1.8 times wider than long.

Ophthalmic somite, epistome, labrum ( Fig. 8A View FIGURE 8 ), and paragnath, without special features.

Mandible (left) ( Fig. 8B View FIGURE 8 ) with corpus damaged, without palp, incisor process ( Fig. 11C View FIGURE 11 ) slender, obliquely truncate distally with 4 small similar acute teeth, molar process ( Fig. 11B View FIGURE 11 ) compressed, anteriorly carinate, tapering distally, without obvious teeth, fringed with short setae.

Maxillula ( Fig. 8C View FIGURE 8 ) with palp ( Fig. 11D View FIGURE 11 ) feebly bilobed, ventral lobe with small distal tubercle with short simple spiniform seta; upper lacinia broad ( Fig. 11E View FIGURE 11 ), distally truncate with 9 stout simple spines, 5 central spines fully fused to lacinia, remaining spines articulated, surface with scattered spiniform setae and simple setae, lower lacinia tapering distally, blunt with numerous long sparsely setulose spiniform setae.

Maxilla ( Fig. 8D View FIGURE 8 ) with simple tapering distally blunt non-setose palp, basal endites fused, rounded, with 11 slender simple marginal setae, coxal endite obsolete, margin convex, non-setose, scaphocerite well developed, about 3.0 times longer than broad, anterior lobe 1.25 times longer than broad, feebly concave medially, posterior lobe slender.

First maxilliped ( Fig. 8E View FIGURE 8 ) with palp simple short, with single preterminal plumose seta medially, basal and coxal endites fully fused, broadly rounded distally, basal portion with medial margin straight, with numerous slender feebly setulose marginal setae, coxal region convex, with single seta, exopod with slender flagellum, setae missing, caridean lobe well developed, epipod sub-quadrate, feebly bilobed.

Second maxilliped ( Fig. 8F View FIGURE 8 ) 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 terminal setae missing; coxa produced medially, rounded, with single short simple seta, epipod simple, twice as long as broad, without podobranch.

Third maxilliped ( Fig. 8G View FIGURE 8 ) reaching to about end of basicerite, ischiomerus and basis semi-fused, ischiomerus broad, 1.75 times longer than proximal width, tapering slightly distally, medial margin feebly biconvex sparsely setose, lateral margin straight, sparsely setose; carpus 0.66 of ischiomeral length, subcylindrical, oval in section, 3.0 times longer than wide, sparsely setose medially; terminal segment 0.8 of carpal length, tapering distally, 4.0 times longer than basal width, with numerous slender finely setulose marginal and distal spines; coxa with medial margin convex, sparsely setose, exopod with slender flagellum with 2 terminal setae (2 missing?); coxa with long low lateral plate, possibly with rudimentary arthrobranch.

Thoracic sternites, second to fifth unarmed, sixth with medial longitudinal carina, seventh and eighth unarmed. (As in P. zarenkovi Ď uriš, 1990, see below).

First pereiopod ( Fig. 9A View FIGURE 9 ) normal, exceeding antennular peduncle by carpus and chela; chela ( Fig. 9 View FIGURE 9 BC) about 0.42 of CL, palm subcylindrical, oval in section, twice as long as proximal depth, tapering slightly distally, with sparse cleaning setae proximo-ventrally, fingers subequal to palm length, slender, broad, tips distally rounded, dactyl tridentate, fixed finger bidentate, opposing surfaces concave, lateral margins finely lamellate distally, entire; carpus subequal to chela length, 4.2 times longer than distal width, tapering slightly proximally, with long cleaning setae distoventrally; merus 1.2 times chela length, 5.5 times longer than central width, slightly swollen proximally; ischium 0.68 of chela length; basis and coxa without special features, coxa without distoventral process.

Major second pereiopod (right) ( Fig. 9D View FIGURE 9 ) massive, chela about 1.5 times CL, palm smooth, glabrous, oval in section, about twice as long as maximal depth at 0.33 of length, fingers ( Fig. 9 View FIGURE 9 FG) about 0.35 of palm length, sparsely setose; dactylus compressed, 0.38 of palm length, dorsal margin convex, cutting edge with well developed molar process on second two fifths, distal two fifths slightly concave, finely denticulate, with about 24 small, fairly uniform teeth ( Fig. 9G View FIGURE 9 ), distally subacute, mainly subquadrate, possibly due to abrasion, tip stout, short, bluntly hooked; fixed finger about 0.33 of palm length, 1.4 times longer than basal width, cutting edge with well developed fossa, medial margin with low acute tooth proximally, ventral margin with rounded lobe, distal cutting edge blunt, entire, tip stout, short, bluntly hooked; carpus short, triangular, about 1.25 times longer than distal width, 0.35 of palm length, tapering strongly proximally, unarmed; merus 0.47 of palm length, twice as long as central depth, slightly swollen centrally, ventral margin with three small acute denticles on central third; ischium 0.36 of palm length, twice as long as distal width, ventral margin without denticles; basis and coxa robust, without special features.

Minor second pereiopod missing.

Third pereiopod ( Fig. 10A View FIGURE 10 ) exceeding antennular peduncle by propod and dactyl, with propod about 0.53 of CL; dactyl ( Fig. 10C View FIGURE 10 ) compressed, biunguiculate, about 0.17 of propod length, unguis clearly demarcated, tip missing, simple, curved, about 0.4 of corpus length, 1.7 times longer than basal width, corpus about 1.4 times longer than basal width, tapering, distal width about 0.38 of basal width, dorsal margin slightly convex, ventral margin with small acute distal accessory tooth (damaged), ventral margin straight, sharp, with rounded swelling proximally bearing stout acute tooth, with long sensory setae laterally; propod ( Fig. 10B View FIGURE 10 ) 4.3 times longer than proximal depth, sparsely setose, tapering distally, distal width 0.5 of proximal depth with pair of stout simple distoventral spines, lateral spine about 0.66 of dactyl length, medial spine shorter, with single preterminal ventral spine, 2 smaller ventral spines at 0.25 and 0.5 of propod length; carpus 0.33 of propod length, 3.0 times longer than central width, unarmed; merus about 1.2 times propod length, 3.6 times longer than central width, unarmed; ischium 0.8 of propod length, 3.3 times longer than distal width, unarmed; basis and coxa robust, without special features.

Fourth pereiopod similar to third, more slender, dactyl ( Fig. 10 View FIGURE 10 EF) with unguis 2.6 times longer than basal width, 0.45 of corpus length, distal corpus with slender acute accessory tooth about 0.33 of unguis length, propod ( Fig. 10D View FIGURE 10 ) 0.78 of third propod length, 4.6 times longer than proximal width, spinulation as in third pereiopod; carpus, merus and ischium similar.

Fifth pereiopods missing.

Uropod ( Fig. 7J View FIGURE 7 ) with protopodite posterolaterally rounded; rami broad, exopod 2.1 times longer than broad, lateral margin feebly convex, sparsely setose, with stout distolateral tooth with much longer spine medially ( Fig. 11F View FIGURE 11 ); diaeresis obsolete; endopod about subequal to exopod length, 2.5 times longer than broad.

Ova of normal pontoniine size, about 30.

Measurements (mms). Post-orbital carapace length, 2.0; carapace and rostrum, 3.0; total body length (approx.), 9.7; major chela, 3.6; minor chela, missing; length of ovum, 0.5.

Colouration. No data.

Etymology. The species name is derived from the name of the sponsoring organisers, CReefs, for the 2009 Heron Island Expedition.

Systematic position. Without the minor second pereiopod the systematic position of this species cannot be fully assessed.

Periclimenaeus creefi appears to most closely resemble P. orbitocarinatus Fransen, 2006 , a species also only known from the holotype specimen which similarly lacks its minor second pereiopod. Both species have the dactyl of the major second pereiopod with a minutely denticulate distal cutting edge and the ambulatory dactyl of the third pereiopod with an acute basal process. They also have a scaphocerite with a small distolateral tooth that does not exceed the distal margin of the lamella, the first pereiopod chelae with slender fingers with small rounded multidentate tips.

Periclimenaeus creefi can be readily distinguished from P. orbitocarinatus by the absence of a distinct postorbital carina. In addition, the rostrum is relatively longer with 5 dorsal teeth (vs 4 in P. orbitocarinatus ), the proximal segment of the antennular peduncle has a strong ventromedial tooth (absent in P. orbitocarinatus ), the major second pereiopod dactyl has about 24 small denticles (vs about 50 in P. orbitocarinatus ), the third ambulatory dactyl has a well developed distal accessory tooth on the corpus (absent in P. orbitocarinatus ), and much larger dorsal spines on the telson.

Host. Not recorded, most probably from an ascidian.

Remarks. The single specimen lacks the minor second pereiopod and has only the right third and fourth pereiopods. The median carina on the sixth thoracic sternite may be unusual or just overlooked in other Periclimenaeus spp. but a similar carina has been illustrated in P. zarenkovi by Ď uriš (1990).