Onycocaris Nobili 1904, sp. nov.
Creators: name: Bruce, A. J.
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Palaemonidae
Onycocaris

description: Genus Onycocaris Nobili, 1904
Onycocaris maui sp. nov. (Figs 1–10)
Diagnosis. Rostrum greatly reduced, dorsally carinate with small up-turned tip, unarmed, inferior orbital angle broadly rounded, distolateral scaphocerite tooth well exceeding lamella, eye subquadrate, incisor process of mandible distally oblique with about 17 small teeth, second pereiopods unequal, dissimilar, near similar in male and females, female major chela dactyl with acute tooth at 0.3 of length, with low, more distal tooth blending with acute tip, teeth finely crenulate, other edges unarmed, fixed finger without lateral flange, merus with 0–3 small acute ventral denticles only, ischium unarmed, male major chela unknown, minor chela dactyl with well developed large acute tip, cutting edge with small acute tooth at half length, distally minutely uniformly denticulate, fixed finger distally bifid with well developed lateral flange, elongate, denticulate, distally acute with stout preterminal teeth, presenting semi-bifid appearance, cutting edges with small acute tooth proximally, distal cutting edges coarsely, irregularly denticulate; merus with minute ventral denticle, ischium without ventral denticles, ambulatory dactyl biunguiculate, with unguis simple, ventral corpus with 6–9 small acute teeth, dorsal telson spines at 0.2, 0.6 of telson length.
Material. (i) post-ovig. Ƥ paratype, CL 2.6, QM W29192, stn. S-05-01, Hekili Point, Maui, Hawaii, 14 March 2005, coll. Marjorie Jumawan, Maria Abdullahi & Cory Pittman, under rock, low intertidal. (ii) ovig. Ƥ, holotype, CL 2.7, QM W29190, 3 allotype, CL 2.0, QM W29191, stn. S-05-02, Hekili Point, Maui, Hawaii, 26 March 2005, coll. Cory Pittman, under rock, low inter-tidal.
Description. Females (Figs 1–6, 9)
Rostrum (Figs 2 A, 3A, B) very short, triangular in dorsal view, barely covering bases of eye stalks, about 0.1 of CL, 4.0 times broader than long, lateral margins concave, continuous with orbital rim, with small up-turned tip, with short unarmed dorsal carina, dorsal margin convex, length about half rostral width, with two dorsal setae and one preterminal seta.
Carapace (Fig. 3 C, D) moderately compressed, depth subequal to CL, without antennal and hepatic teeth, inferior orbital angle strongly produced, largely covering eyes laterally, broadly rounded, extending far beyond level of rostral tip, anterolateral angle broadly rounded, extending slightly beyond level of inferior orbital angle.
Abdomen (Fig. 1) stout, smooth, glabrous, with first three pleura broadly expanded, enclosing very large marsupial cavity, fourth and fifth smaller, posteriorly rounded, sixth segment (Fig. 3 F) depressed, subequal to length of fifth, 0.25 of CL, 1.8 times broader than long, posteroventral angles well developed, acute with very acute tips, posterolateral angles small, acute.
Telson (Fig. 3 G) about 0.5 of CL, 2.0 times sixth segment length, 0.57 times longer than maximal width, lateral margins feebly convex, posteriorly convergent, sparsely setose, with paired small subequal submarginal dorsal spines, about 0.08 of telson length, at 0.37 and 0.75 of telson length, posterior margin (Fig. 3 H) broadly rounded, with small acute median point, lateral spines similar to dorsal spines, intermediate spines robust, about 3.0 times lateral spine length, submedian spines slender, 0.75 of intermediate spine length, non-setulose.
Antennule, carpocerite extending as far as scaphocerite lamina. Antennule with proximal peduncular segment twice as long as wide, distolateral angle (Fig. 2 B) long, slender, reaching to two thirds of intermediate segment length, stylocerite acute, reaching half segment length, without ventromedial process; intermediate and distal segments about half proximal segment length, upper flagellum biramous, first four segments fused, shorter free ramus with single segment, about eight groups of aesthetascs present, longer ramus with seven slender segments.
Antenna with basicerite robust, unarmed; carpocerite subcylindrical, 4.5 times longer than width, slightly exceeding scaphocerite lamella; scaphocerite (Fig. 2 C) well developed, twice as long as central width, distal margin broadly rounded, medial margin continuously convex, lateral margin straight, with strong distolateral tooth, about 0.17 of lamella length.
Eyes (Figs. 2 D, 3E)) short, stout, cornea hemispherical, about 0.16 of CL, 0.6 of stalk length, without pigment spot, stalk distomedially subquadrate, as wide as long with contiguous medial surfaces flattened.
Mouthparts (Fig. 4) typical of the genus.
Mandible (Fig. 4 A) with slender corpus without palp; molar process (Fig. 4 B) subcylindrical, obliquely truncate distally, ventral margin with short setae, dorsal margin crenulate, with several short stout spinules distally; incisor process (Fig. 4 C) distally oblique with about 17 small acute teeth.
Maxillula (Fig. 4 D) with feebly bilobed palp (Fig. 4 E), upper lobe small, rounded, lower lobe larger with short simple terminal seta; upper lacinia (Fig. 4 F) f eebly tapering, distally damaged, rounded, with few short simple spines and setulose setae; lower lacinia tapering distally with about eight slender spiniform setae.
Maxilla (Fig. 4 G) with non-setiferous tapering palp, about 4.3 times longer than wide; basal endite simple, curved medially, distally rounded with nine slender simple setae; coxal endite slightly angularly produced medially, non-setose; scaphognathite well developed, about 3.2 times longer than wide, posterior lobe well developed, narrow, subequal to anterior lobe length, anterior lobe about 1.5 times longer than wide, medial margin straight.
First maxilliped (Fig. 4 H) with non-setiferous tapering palp, about 4.5 times longer than wide, 1.2 times length of maxillary palp; basal and coxal endites fused, broadly rounded distally, medial margin straight, sparsely setose with simple setae; endopod with well developed flagellum with four plumose terminal setae, caridean lobe well developed, length about 0.8 of flagellum length, with numerous feebly setulose marginal setae; epipod well developed, deeply bi-lobed, cordiform.
Second maxilliped (Fig. 4 I) of normal form; dactyl about 2.7 times longer than wide, medial margin straight, densely fringed with serrulate spines; propod distally rounded, with few slender spiniform setae; carpus, ischiomerus and basis without special features, exopod well developed, slender, with four plumose terminal setae; coxa medially rounded, non-setose; without epipod.
Third maxilliped (Fig.4 J) with endopod slender, extending to distal margin of antennal scale; endopod with ischiomerus about 2.7 times longer than proximal width, tapering distally to 0.2 times proximal width, lateral margin near straight, non-setose, medial margin similar, with sparse simple setae; carpus subcylindrical, slightly tapering proximally, 2.7 times longer than maximal width, with several robust setae medially and two distolaterally; terminal segment 0.8 of carpal length, 3.0 times longer than maximal width, tapering distally, with five groups of slender feebly setulose spiniform setae medially, fewer shorter setae laterally; basis robust, mainly fused with ischiomerus, medial margin convex, non-setose, exopod well developed, exceeding ischiomerus, with four plumose terminal setae, coxa stout, medial margin not produced, non-setose, laterally with well developed low rounded lateral plate; rudimentary arthrobranch possibly present.
Fourth thoracic sternite (Fig. 5 A) broad, with rounded median boss anteriorly and low median carina posteriorly; posterior sternites without special features.
First pereiopod (Fig. 5 A) very slender, exceeding carpocerite by distal fourth of merus, chela (Fig. 5 B) about 0.35 of CL, palm slender, subcylindrical, slightly tapering distally, about 6.4 times longer than proximal depth, without cleaning setae proximally, fingers (Fig. 5 C) about 0.2 of palm length, fingers similar, with entire cutting edges, stout strongly hooked tips and numerous long curved simple setae distally, basket formation feebly developed; carpus about 1.7 times chela length, 11.5 times longer than distal width, tapering proximally, with two slender cleaning setae distoventrally; merus subequal to carpal length, slightly more robust, subcylindrical; ischium about 1.2 times chela length, 5.5 times longer than central width; basis and coxa of subequal length, about 0.6 of palm length, without special features.
Second pereiopods well developed, unequal, dissimilar.
Major second pereiopod (Fig. 6 A) large, robust, chela about 1.5 times CL; palm smooth, compressed, slightly enlarged centrally, posterodorsally produced, about 1.15 times longer than deep; dactyl (Fig. 6 B) 0.87 of palm length, about 3.1 times longer than proximal depth, slightly curved, dorsally convex, with sparse setae, tip acute, stout, curved, crossing tip of fixed finger, cutting edge with two well developed teeth separated by broad concavities, at about 0.5 and 0.7 of dactyl length, proximal tooth subacute, distal tooth lower, broader, less acute, with three groups of long setae on distolateral margin, sparse simple setae proximally, distal cutting edge entire; fixed finger (Fig. 6 C) with simple acute tip, without lateral flange, slightly depressed, medially scaphoid, 0.73 of palm length, tapering strongly distally, 2.0 times longer than proximal depth, cutting edge with two teeth on proximal half, proximal tooth long, low, with dorsal margin minutely crenulate, distal tooth short, erect, truncate with distal border convex, dorsal margin finely crenulate, with numerous long setae; carpus short stout, about 0.7 of palm length, 1.5 times longer than maximal width, distodorsally excavate, tapering strongly proximally, unarmed; merus 0.6 of palm length, 1.6 times longer than central depth, tapering distally and proximally, with two small acute ventral tubercles; ischium 0.5 of palm length, 1.3 times longer than distal width, tapering strongly proximally, unarmed; basis and coxa short, robust, without special features.
Minor second pereiopod (Fig. 6 D) with chela about 1.2 times CL, palm smooth, non-setose, moderately compressed, posterodorsally produced, 1.3 times longer than deep; fingers crossing distally, dactylus 0.82 of palm length, 3.6 times longer than central depth, dorsal margin convex, sparsely setose, tip simple, acute, cutting edge proximally concave with small acute tooth distally, separated by small notch from straight finely denticulate cutting edge extending to base of terminal tooth, denticulations sub-uniform, about 22, slightly abraded, acute, with five groups of longer simple submarginal setae laterally, fixed finger (Fig. 6 E) about twice as long as proximal depth, slightly depressed, medially scaphoid, tapering strongly distally with well developed distolateral flange and strongly bifid tip (Fig. 6 F), cutting edge with stout acute hooked tip, with small acute tooth at half length, proximal cutting edge feebly convex, minutely denticulate (Fig. 2 E), denticles numerous, about 25, irregular, slightly larger centrally, distal cutting edge similar with coarser denticulations extending onto base of terminal tooth, lateral flange (Fig. 6 G) with stout distal tooth, slightly shorter than inner tooth (Fig. 2 FG), with convex denticulate carina proximally for about 0.4 of fixed finger length, about 20 minute denticulations, increasing in size distally, distal denticulations more robust, with numerous long simple setae; carpus about 0.6 of palm length, 1.8 times longer than distal depth, tapering strongly proximally, distodorsally excavate, ventrolaterally produced, unarmed; merus about 0.7 of palm length, centrally swollen, 1.7 times longer than central width, without distoventral teeth, ventral margin with 2 small acute tubercles; ischium 0.5 of palm length, 0.6 of meral length, 1.5 times longer than distal width, tapering strongly proximally, without distoventral tooth, ventral margin without acute tubercles; basis and coxa robust, without special features.
Third pereiopod (Fig. 5 D) robust; dactyl (Fig. 2 H, 5F) compressed, about 1.56 times longer than proximal depth, 0.27 of propod length, unguis 3.0 times longer than basal width, curved, unarmed, corpus with dorsal margin convex, ventral margin more strongly convex with large distal tooth, slightly recurved with distal margin feebly notched, proximal ventral border with 7 small acute teeth, acute, erect, with central teeth larger than adjacent teeth, with single long distolateral seta; propod (Fig. 5 E) 0.35 of CL, 3.8 times longer than proximal depth, tapering slightly distally, with 2 small distoventral spines, 3 small isolated ventral spines; carpus 0.6 of propod length, 3.0 times longer than distal width, tapering slightly proximally, unarmed; merus 1.2 times propod length, 2.6 times longer than central width, tapering slightly proximally and more distally; ischium 0.9 of propod length, 2.0 times longer than distal width, tapering proximally, unarmed; basis and coxa robust, without special features.
Fourth pereiopod (Fig. 5 G) similar to third pereiopod, dactylar corpus with accessory tooth similar, corpus with 8 small ventral teeth, propod about 0.9 of third propod length, more robust, 4.0 times longer than proximal depth, with 1 small distoventral spine, 3 similar smaller ventral spines.
Fifth pereiopod (Fig. 5 H) similar to third pereiopod, dactylar corpus (Fig. 5 I), more elongate, about 2.2 times longer than depth, corpus with 9 acute ventral denticles, propod about 1.1 times third propod length, 4.8 times longer than deep, with 2 small distoventral spines concealed by distolateral tuft of simple setae, single similar ventral spine only.
Uropod (Fig. 3 I) with protopod unarmed; exopod broad, 2.0 longer than width, 1.1 times telson length, lateral margin convex proximally straight distally, sparsely setose, with small acute distolateral angle (Fig. 3 J) with larger mobile spine medially; endopod subequal to exopod length, 2.4 times longer than broad.
Ova small and numerous, about 50.
Male (Figs 7–8, 10). Generally as females, smaller and with more slender abdomen; missing major second pereiopod.
Rostrum (Fig. 7 B) horizontal with small up-turned tip and low median carina, scarcely covering bases of eyes (Fig. 7 A). Carapace with inferior orbital angle broadly rounded. Antennule (Fig. 7 C) with distolateral angles of proximal peduncular segment (Fig. 7 D) produced, rounded, without ventromedial tooth; upper flagellum biramous with 4 segments, with 8 groups of aesthetascs, short free ramus single segmented, long free ramus with 7 segments, lower flagellum filiform with 10 segments. Antenna (Fig. 7 E) with basicerite unarmed, carpocerite well exceeding scaphocerite lamella, scaphocerite (Fig. 7 F) 2.2 times broader than long, with well developed acute distolateral tooth, far exceeding lamella, about 0.15 of lamella length.
Minor second pereiopod chela (Fig. 8 A) 1.7 times CL, dactyl (Fig. 8 B) 0.75 of palm length, with small acute tip, small blunt tooth at about half length, cutting edge minutely denticulate over distal two-thirds, denticles uniform throughout length, about 32; fixed finger distally bifid (Fig. 8 CEF), with paired acute tips, medial cutting edge with low, minutely denticulate carina proximally (Fig. 8 D), about 5 denticles, distal cutting edge discontinuously minutely denticulate, about 30 sub-uniform denticles, lateral flange (Fig. 8 E) with stouter distal tip, uniformly minutely denticulate, denticulate cutting edges enclosing deep narrow longitudinal groove, about 25 denticles; proximal segments similar to females but merus without ventral denticles.
Ambulatory pereiopods similar to females. Third pereiopod propod (Fig. 7 G) 0.4 of CL, dactyl (Fig. 7 H) 0.3 of propod length, unguis 0.4 of corpus length, slightly curved, unarmed, corpus 2.1 times longer than maximal depth, with well developed bidentate distal accessory tooth (Fig. 7 I), distal tooth smaller, angularly acute, proximal tooth larger, distal margin straight, posterior margin convex, ventral margin of corpus with 7 small erect acute denticles, first, second and seventh smaller, third to sixth more robust; propod slightly bowed, about 4.5 times longer than proximal depth, with well developed distoventral spines and 5 smaller ventral spines.
Pleopods without special features. First pleopod endopod (Fig. 7 J) with endopod about 3.0 times longer than broad, distally rounded, with 3 long setulose spiniform setae, about 1.5 times endopod length, distal medial margin with 3 short plumose setae. Second pleopod endopod (Fig. 7 K) with appendices (Fig. 7 L) at about half length; appendix masculina with rudimentary corpus bearing single long rigid sparsely setulose spine, about half of endopod length; appendix interna without special features.
Measurements. Holotype female, carapace and rostrum, 3.0 mm, postorbital carapace length, 2.75 mm; total body length (approx.), 10.5 mm; major second pereiopod chela, 3.6 mm; minor second pereiopod chela, 2.6 mm; length of advanced eyed ovum, 0.6 mm. Allotype male, carapace and rostrum 2.75 mm; postorbital carapace length, 2.4 mm; total body length (approx.), 8.0 mm; minor second pereiopod chela, 3.5 mm.
Systematic position. Onycocaris maui most closely resembles O. balssi Bruce, 1978. The male of O. balssi is unknown. The females differ in the following characters:
(i) presence of an up-turned rostral tip in O. maui (versus not up-turned tip in O. balssi). (ii) distolateral tooth of proximal segment of antennular peduncle longer, exceeding half intermediate segment length (versus less than half in O. balssi). (iii) distolateral tooth of scaphocerite longer, more robust, about 0.165 of scaphocerite (versus 0.14 in O. balssi). (iv) endite of maxilla.
Endite of maxilla slender (versus broad in O. balssi). (v) third ambulatory pereiopod dactyl with accessory tooth feebly bidentate, distal tooth blunt (versus strongly acutely bidentate in O. balssi); ventral denticles anteroverted (versus erect in O. balssi). (vi) Sixth abdominal somite with posterolateral and posteroventral angles more acute (versus less acute in O. balssi).
Host. Haliclona sp., det. J.N.A. Hooper, 7-19-05.
Etymology. Named after the locality of capture, the island of Maui, Hawaiian Islands, used in apposition.
Colouration. Female (Fig. 9) generally translucent with whole body densely covered with small white spots, appendages colourless, ovary pale green, cornea white. Male (Fig. 10) generally translucent, with sparse scattered small white dots over body.
Distribution. Known only from the type material from Maui, Hawaiian Islands.
Remarks. Onycocaris maui sp. nov. is a member of the Onycocaris quadratophthalma species group (Bruce, 2011, Komai & Itou, 2012), characterized by very short unarmed rostrum, quadrate or subquadrate eyes, second pereiopod chelae without medial rows of small isolated teeth on fingers, merus and ischium of second pereiopods without or with distoventral tooth. This definition is modified to allow the inclusion of the closely related O. maui. It may be noted that in the original designation of the O. quadratophthalma species group by Bruce (2011) O. trullata was included. Onycocaris trullata does possess small medial teeth on the fingers of the second pereiopods (Bruce, 1978, fig. 40) and is not a member of this group and is omitted from the key below.
Of the species of this group, both sexes are known for O. fujinoi, O. hyamaensis and O. maui, with females only for O. balsii and O. quadratophthalma. None are known from the male only. The following key is therefore based on the female specimens only. Of the three quadratophthalma group species with known males, all have sexually dimorphic second pereiopod chelae, with those of the males showing a well developed denticulate lateral lamina not present in the females.
description: Published as part of Bruce, A. J., 2013, Onycocaris maui sp. nov., a new pontoniine sponge associate (Crustacea: Decapoda: Palaemonidae) from the Hawai'ian Islands, pp. 377-388 in Zootaxa 3691 (3) on pages 378-387, DOI: 10.11646/zootaxa.3691.3.6, http://zenodo.org/record/218536