Periclimenaeus aurantiacus, Bruce, A. J., 2014

Bruce, A. J., 2014, Periclimenaeus species (Crustacea: Decapoda: Pontoniinae) from Hawaii, Zootaxa 3754 (4), pp. 461-472 : 463-470

publication ID	https://doi.org/ 10.11646/zootaxa.3754.4.7
publication LSID	lsid:zoobank.org:pub:33B82C26-7192-4B25-AB47-F49EEC4C23D2
DOI	https://doi.org/10.5281/zenodo.5316588
persistent identifier	https://treatment.plazi.org/id/F32E87DA-FF9F-0E79-EEBF-FF2C645E2BDD
treatment provided by	Plazi
scientific name	Periclimenaeus aurantiacus
status	sp. nov.

Treatment

Periclimenaeus aurantiacus View in CoL sp. nov.

( Fig. 2–9 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 View FIGURE 8 View FIGURE 9 )

Material examined. 1 ♀, holotype, Maalaea Bay, Maui Island, Hawaii, 20.7792° N 156.4906° E, Halimeda field, 8–10 m, coll. P. Fiene, C. Pittman, 5 October 2007, FMNH UF12466.

1 ♀, juvenile, paratype, Maalaea Bay, Maui Island, Hawaii, Halimeda kanaloana bed, algal wash, 9–10 m, coll. C. Pittman, S- 13-02, 7 April, 2013, QM-W29200.

Diagnosis. —Rostral dentition 3–5/0, slender, down-curved, carapace without supraorbital spines, tubercles or postorbital carina, first abdominal tergite without anterior dorsal lobe, scaphocerite with distolateral tooth not exceeded by lamella, incisor process of mandible multidentate, first pereiopod fingers cyathiform, edges denticulate, second pereiopod chelae near smooth, major dactyl with minute molar process, cutting edge distally elongate, entire, fixed finger with elongate groove, ventral margin strongly raised, entire; merus and ischium ventrally denticulate, minor second pereiopod dactyl with cutting edge without molar process, convex, entire, merus with ventral denticle, third pereiopod with dactylar unguis unarmed, corpus with distal accessory tooth, with five acute ventral teeth, without proximal ornamentation, third, fourth and fifth pereiopods similar, fourth dactyl with three ventral teeth, fifth unarmed, propod and carpus slender, caudal fan normal, telson with well developed dorsal spines at 0.1 and 0.6 of telson length, exopod of uropod with posterolateral tooth and spine only.

Description. Holotype ♀ ( Figs 2–6 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 , 8 View FIGURE 8 ).

Rostrum ( Fig. 2 View FIGURE 2 A) slender, compressed, short, feebly depressed, about 0.45 of CL, reaching to end of proximal segment of antennular peduncle, dorsal carina with five similar acute teeth on distal four fifths, sparse interdental setae, ventral carina obsolete, margin convex, unarmed.

Carapace ( Fig. 2 View FIGURE 2 B) smooth, glabrous, slightly compressed, without supraorbital spines or tubercles, with small postorbital “shoulder”, orbit feebly developed, without associated carinae, antennal tooth ( Fig. 2 View FIGURE 2 B) well developed.

Abdomen without anteromedian dorsal lobe on first segment, pleura of first three segments enlarged, broadly rounded, fourth and fifth smaller, sixth 1.1 times length of fifth, 0.55 of telson length, posterolateral tooth and posteroventral tooth ( Fig. 2 View FIGURE 2 G) well developed.

Telson ( Fig. 2 View FIGURE 2 H) 0.6 of CL, about 2.0 times sixth segment length, twice as long as maximal breadth, lateral margins posteriorly straight, convergent to rounded posterior margin ( Fig. 6 View FIGURE 6 H), 0.33 of maximal width, without median point, two pairs of small subequal dorsal spies at 0.1 and 0.6 of telson length, 0.2 of telson length, posterior margin ( Fig. 6 View FIGURE 6 H) with small lateral spines, 0.25 of distal dorsal spine length, robust intermediate spines, 0.12 of telson length, submedian spines of similar length, more slender, non-setulose.

Antennule with proximal segment of peduncle ( Fig. 2 View FIGURE 2 C) about 1.6 times longer than central width, medial margin straight, with acute ventral tooth at about 0.5 of length, lateral margin produced, distally concave, with robust acute distolateral tooth, stylocerite acute, phylliform, statocyst with granular statolith, intermediate and distal segments short, subcylindrical, subequal, about 0.3 of proximal segment length, upper flagellum biramous, proximal four segments fused, short free ramus with single segment, with twelve groups of aesthetascs, longer free ramus with six segments; lower flagellum short, filiform, with eight segments.

Antenna ( Fig. 2 View FIGURE 2 D) with basicerite unarmed; carpocerite reaching to middle of intermediate segment of antennular peduncle, not exceeding scaphocerite, subcylindrical, about 5.0 times longer than wide; merocerite and ischiocerite without special features; scaphocerite ( Fig. 2 View FIGURE 2 E) normal, exceeding carpocerite length, about 2.5 times longer than distal width, distal lamella rounded, lateral margin straight with robust distolateral tooth at 0.85 of length, 0.12 of lateral margin length, reaching almost to distal margin of lamella.

Eye ( Fig. 2 View FIGURE 2 F) with cornea hemispherical, oblique, diameter about 0.18 of CL, 0.9 of medial stalk length, without visible accessory pigment spot, stalk about 1.2 times longer than deep, subcylindrical, as long as wide.

Mouthparts, right side dissected.

Mandible ( Fig. 3 View FIGURE 3 A) with corpus robust, without palp; molar process ( Fig. 6 View FIGURE 6 A) subcylindrical, obliquely truncate distally, dorsal surface with thin lateral plate with small dorsal tooth, ventral aspect finely denticulate; incisor process ( Fig. 6 View FIGURE 6 B) slender, distally oblique, with seven small acute distal teeth.

Maxillula ( Fig. 3 View FIGURE 3 B) with palp feebly bilobed, lower lobe with small simple seta; upper lacinia ( Fig. 6 View FIGURE 6 C) obliquely convex distally with seven small simple marginal spines, with three longer submarginal spines and numerous setae; lower lacinia slender, feebly tapering distally, terminally rounded with six long slender spiniform setae.

Maxilla ( Fig. 3 View FIGURE 3 C) with short flattened tapering palp), about 3.7 times longer than basal width, sparsely setose proximo-laterally, basal endite distally swollen, feebly bilobed, 1.5 times longer than distal width, with two sets of eight and five slender terminal setae; scaphognathite normal, narrow, about 3.5 times longer than central width, anterior lobe 1.4 times longer than wide, medial margin concave, posterior lobe 2.4 times longer than basal width; coxal medial margin convex, non-setose.

First maxilliped ( Fig. 3 View FIGURE 3 D) with flattened palp without seta, basal and coxal endites fully fused, distally rounded, medial margin straight with numerous slender setae, decreasing in size proximally, exopod normal, flagellum slender, distal portion missing, with caridean lobe large, about 1.6 times longer than central width, epipod well developed, triangular, feebly bilobed.

Second maxilliped ( Fig. 3 View FIGURE 3 E) with normal endopod, dactylar segment narrow, 2.4 times longer than broad, with numerous long slender serrulate marginal spines, propodal segment antero-medially rounded, not produced, with several long slender plumose marginal spines, carpus, merus and ischiobasis without special features, exopod with slender flagellum with four long terminal setae, coxa medially produced, rounded, with small oval epipod laterally, without podobranch.

Third maxilliped ( Fig. 3 View FIGURE 3 F) with ischiomerus and basis fully fused, combined segment 4.0 times longer than basal width, tapering distally, sparsely setose medially, carpus robust, subcylindrical, 0.5 of ischiomeral-basis length, 3.3 times longer than distal width, tapering proximally, with few spiniform setae medially, terminal segment 0.66 of carpal length, about 3.0 times longer than proximal width, tapering distally, with numerous spiniform setae medially and distally, exopod with slender flagellum with four long plumose terminal setae, coxa robust, medial margin straight, excavate, non-setose, lateral margin with well developed rounded lateral plate, without arthrobranch.

Thoracic sternite s narrow, unarmed, seventh without median carina.

First pereiopod ( Fig. 4 View FIGURE 4 A) robust, short, merus reaching to end of antennular peduncle, chela ( Fig. 4 View FIGURE 4 B) about 0.37 of CL, palm subcylindrical, slightly compressed, tapering distally, 2.2 times longer than deep, fingers 0.4 of palm length, broad with rounded tips distally, dactyl ( Fig. 4 View FIGURE 4 C) cymbiform, 1.4 times longer than broad, with single small distal tooth, medial and lateral cutting edges with about 20 minute recurved denticles distally ( Fig. 6 View FIGURE 6 D), fixed finger similar, cutting edges entire, carpo-propodal cleaning setae obsolete; carpus subequal to chela length, 4.0 times longer than distal width, tapering proximally, with few distoventral setae; merus about 1.2 times chela length, 4.8 times longer than maximal width, tapering slightly distally; ischium 0.75 of chela length; basis without special features; coxa normal, with small ventral process.

Second pereiopods unequal, dissimilar. Major second pereiopod ( Fig. 4 View FIGURE 4 D) with chela about 1.4 times CL, palm subcylindrical, slightly swollen centrally, compressed, about 1.8 times longer than depth, smooth, generally glabrous with few minute ventral denticles; fingers ( Fig. 4 View FIGURE 4 E) glabrous, 0.43 of palm length, dactyl ( Fig. 4 View FIGURE 4 F) exceeding fixed finger, about 2.0 times as long as maximal depth, compressed, dorsal margin strongly convex, tip hooked, robust, acute, cutting edge with very small molar process proximally, with ridge extending distally on lateral surface, medial cutting edge expanded, concave ( Fig. 4 View FIGURE 4 G), entire; fixed finger about 1.3 times longer than proximal depth, cutting edge with deep longitudinal groove for most of length, lateral margin shallow with central angle, medial margin strongly raised, acute, acting with shearing action against dactylar cutting edge, medial margin with acute process, lateral margin with rounded glabrous process, tip acute, strongly hooked, distal cutting edge entire; carpus about 0.38 of palm length, 1.4 times longer than maximal depth, distally excavate, tapering proximally, unarmed; merus robust, 0.43 of palm length, 2.0 times longer than central depth, slightly swollen centrally, ventral margin with six small acute denticles ( Fig. 6 View FIGURE 6 E); ischium subequal to meral length, twice as long as distal width, tapering proximally, with few minute ventral asperities; basis and coxa robust, without special features.

Minor second pereiopod ( Fig. 4 View FIGURE 4 H) with chela about 0.83 of CL, 0.55 of major chela length, palm ( Fig. 4 View FIGURE 4 I) subcylindrical, slightly swollen proximally, compressed, about 2.2 times longer than depth, smooth, glabrous; fingers about 0.4 of palm length, dactyl ( Fig. 4 View FIGURE 4 J), about 2.0 times longer than maximal depth, slightly exceeding fixed finger, compressed, dorsal margin strongly convex, tip with small hooked acute tooth, cutting edge ( Fig. 4 View FIGURE 4 J), concave, entire; fixed finger about 1.5 times as long as proximal depth, generally similar to major chela but smaller; proximal segments also similar but merus with only one small acute ventral tooth.

Third pereiopod ( Fig. 5 View FIGURE 5 A) robust; dactyl ( Fig. 5 View FIGURE 5 C) about 0.27 of propod length, compressed, unguis robust, curved, 2.5 times longer than basal width, 0.38 of dorsal corpus length, without ornamentation, corpus with dorsal margin slightly convex, about 2.7 times length of unguis, ventral margin slightly convex, with acute distal accessory tooth, with six smaller acute denticles; propod ( Fig. 5 View FIGURE 5 B) about 0.46 of CL, robust, compressed, 4.0 times longer than proximal depth, tapering slightly distally, with stout distoventral spine laterally, shorter, slender spine medially, spines dorsally denticulate ( Fig. 6 View FIGURE 6 F), with four ventral spines, sparsely setose; carpus with similar proportions to propod, not swollen, compressed, 3.0 times longer than central width, 0.7 times longer than propod length, unarmed; merus robust, 1.1 times propod length, compressed, 3.0 times longer than proximal width, unarmed; ischium 0.8 of propod length, 2.2 times longer than distal width, tapering strongly proximally, unarmed; basis and coxa stout, without special features.

Fourth pereiopod ( Fig. 5 View FIGURE 5 D) similar to third, shorter, more slender, dactyl ( Fig. 5 View FIGURE 5 F) similar, corpus with dorsal margin less convex, with three ventral denticles, propod ( Fig. 5 View FIGURE 5 E) 0.62 of third propod length, 0.33 of CL, 4.5 times longer than proximal width, with distoventral pair of spines and three ventral spines.

Fifth pereiopod ( Fig. 5 View FIGURE 5 G) similar to fourth, shorter, more slender, dactyl ( Fig. 5 View FIGURE 5 I) 0.23 of propod length, without distoventral tooth and ventral denticles, propod ( Fig. 5 View FIGURE 5 H) subequal to third propod length, 0.6 of CL, 6.6 times longer than proximal width, with distoventral spines, one distal ventral spine.

Pleopods without special features, second pleopod removed ( Fig. 6 View FIGURE 6 G), protopod medially non-setose, endopod with appendix interna only,.

Uropods ( Fig. 2 View FIGURE 2 I) about as long as telson tip, protopodite laterally unarmed; exopod about twice as long as central width, lateral margin feebly convex with small acute distolateral tooth with 3.0 times larger mobile spine medially ( Fig. 6 View FIGURE 6 I); endopod of similar length, 2.4 times longer than central width.

Paratype. Juvenile ♀, ( Figs 7 View FIGURE 7 , 9 View FIGURE 9 )

Generally similar to holotype but smaller and more slender, lacking major second pereiopod. Rostral dentition ( Fig. 7 View FIGURE 7 A) 3/0, rostrum slightly depressed, reaching to mid-point of anteroverted eye, dorsal teeth acute, similar; corneal diameter about 0.28 of CL; minor second pereiopod fingers ( Fig. 7 View FIGURE 7 BC) similar to holotype, dactyl without molar process, cutting edge convex, entire, sharp, fixed finger with large acutely elevated medial flange, lower ventral flange, merus with single acute ventral tooth; third pereiopod dactyl ( Fig. 7 View FIGURE 7 D) biunguiculate, corpus with four small acute denticles; fifth pereiopod with simple dactyl.

Measurements, (mms).

Holotype female—post-orbital carapace length, 2.4; carapace and rostrum, 3.2; total body length (approx.), 10.4; major second pereiopod chela length, 4.4; minor second pereiopod chela length 2.8.

Paratype female—post-orbital carapace length, 1.0; carapace and rostrum, 1.3; total body length (approx.), 3.5; minor second pereiopod chela length, 1.0.

Host. Uncertain, obtained from algal washings from Halimeda bed where sponges and ascidians were abundant.

Colouration. Larger female holotype ( Fig. 8 View FIGURE 8 ) freshly dead, generally translucent, body and appendages covered with larger red and scattered small black spots. Lack of reddish colouration in detached second pereiopod may be due to having become separated. Smaller female paratype ( Fig. 9 View FIGURE 9 ) generally a deep uniform orange colouration, without transparent spots.

Etymology. Named from aurantiacus (Latin) , orange, after the life colouration of the paratype specimen.

Systematic position. A member of the Periclimenaeus Group 3 noted (see Bruce, 2013) with the third pereiopod dactyl having a distal accessory tooth on the corpus, ventral cutting edge denticulate and without proximal ornamentation. This group contains 18 species. Periclimenaeus aurantiacus most closely resembles P. tchesunovi Ďuriš, 1990 , but differs in a number of important characters, particularly in regard to the second pereiopods.

The two species share the following characters:—carapace without supraorbital tubercles; first abdominal tergite without median anterodorsal lobe; basicerite without rounded dorsolateral lobe; first pereiopod fingers broad, deeply cymbiform with distal margins of cutting edges of dactyl acutely denticulate, fixed finger cutting edges entire; minor second pereiopod dactyl without molar process; second pereiopod chelae with finger tips not heavily sclerotised, chelae fingers with tips simple; merus ventrally denticulate; third ambulatory dactyl with longer acute unguis and shorter acute distal accessory tooth, ventral border of ambulatory dactylar corpus with large acute denticles.

The species may be separated by the following differences.

(1) rostrum with dentition 3–5/0 in P. aurantiacus (6/ 1 in P. tchesunovi ), (2) dorsal telson spines at 0.1 and 0.6 in P. aurantiacus (0.1 and 0.4 in P. tchesunovi ), (3) distolateral tooth of scaphocerite not exceeding lamella in P. aurantiacus (exceeding lamella in P. tchesunovi ), (4) first pereiopod with fingers 0.5 of palm length, 4.0 times longer than broad, dactylar teeth recurved in P. aurantiacus (0.8 and distally everted in P. tchesunovi ), (5) major second pereiopod dactyl with minute molar process proximally and long laminar concave entire cutting edge laterally, dactyl tip slender, acute, fixed finger deeply hollowed along most of length, lateral margin raised, with central bulge, medial margin more strongly raised, concave, with small acute tip in P. aurantiacus (with large molar process in P. tchesunovi , medial cutting edge of fixed finger with deep fossa proximally, medial cutting edge with slender acute process, with stout blunt tip distally), (6) minor second pereiopod dactyl, fixed finger similar to major but lateral cutting edge more strongly raised, angular, cutting with shearing motion in P. aurantiacus (not shearing in P. t c h e s u n o v i), and (7) seventh thoracic sternites without median carina in P. aurantiacus (present in P. tchesunovi ).

Remarks. Periclimenaeus aurantiacus is notable particularly for the very small molar process on the major second pereiopod dactyl, a feature not noted in any other species of the genus.