Lebbeus cristagalli, Poore, 2010

Poore, Gary C. B., 2010, Two crested and colourful new species of Lebbeus (Crustacea: Caridea: Hippolytidae) from the continental margin of Western Australia *, Zootaxa 2372, pp. 126-137 : 131-134

Lebbeus cristagalli sp. nov.

( Figs 1A, 1B, 4)

Material examined. Holotype: Western Australia, north-western Australia, near Ashmore Reef (12° 28.53'S, 123°25.04'E – 12°29.58'S, 123°25.00'E), 397–405 m, beam trawl, D. Bray et al. on FRV Southern Surveyor, 07.VII.2007 (stn SS05-2007 189), WAM C40056 (female, pocl 7.4 mm) . Paratypes: same data as holotype, NMV J58388 (male, pocl 6.4 mm); Imperieuse transect (17°21.5'S, 118°57.3167'E – 17°20.88'S, 118°56.8'E), 437–446 m, beam trawl, D. Bray et al. on FRV Southern Surveyor, 15.V.2007 (stn SS05-2007 056), NMV J58315 (male, pocl 12.7 mm); off Karratha (18°53' S, 116°10' E), 458– 456 m, A.J. Bruce on RV Soela, 30.I.1984 (stn S01/84/12), NTM CR000570 (ov. female, pocl 15 mm); off Port Hedland (18°05'S 118°10'E), 408– 396 m, trawl, T. Davis on RV Soela, 2.II.1984 (stn S01/84/27), NTM CR000564 (male, pocl 8.1 mm); off Eighty Mile Beach (17°34.12'S, 118°43.58.8'E), 405 m, trawl, T. Davis on RV Soela, 3.II.1984 (stn S01/84/ 32), NTM CR000562 (ov. female, pocl 15.2 mm); off Eighty Mile Beach (17°15'S, 119°13'E), 435 m, trawl, B. Wallner on KFV Comac Endeavour, 5.XI.1985, NTM CR007028 (ov. female, pocl 17.4 mm); off Broome (16°53.0'S, 119°50.8'E), 450 m, trawl, T. Davis on RV Soela, 5.II.1984 (stn S01/84/42), NTM CR000565 (ov. female, pocl 15 mm); off Broome (16°22'S, 120°21'E), 456– 452 m, trawl, A.J. Bruce on RV Soela, 5.II.1984 (stn S01/84/45), NTM CR000582 (2 females, pocl 14.5– 12.6 mm) . Non-type material: Timor Sea (9°35'S, 129°28'E) 360–396 m, trawl, B. Wallner on FV Territory Pearl, 18.I.1988, NTM CR006897 (ov. female, pocl 15.2 mm) .

Diagnosis. Carapace high-crested, triangular in profile, with 6–8 forwardly directed teeth on rostrum and anterior two-thirds of carapace. Second-last posterior tooth highest in profile. Rostrum a continuation of carapace crest, reaching almost to distal margin of first antennular article; apex acutely triangular, with or without small spine ventral to apex ( Figs. 4A, E–G). Mandibular incisor with 2 or 3 fine distal serrations ( Fig. 5C). Maxilliped 3 with 19−32 corneous spines, rarely more than 25 ( Fig. 4D). Pereopods 1 and 2 with epipods. Colour − see description below ( Figs. 4A–B).

Description of holotype. Carapace high-crested, triangular in profile, with 6–8 forwardly directed teeth on rostrum and anterior two-thirds of carapace. Second-last posterior tooth highest in profile. Rostrum a continuation of carapace crest, reaching almost to distal margin of first antennular article; apex acutely triangular, with or without small spine ventral to apex ( Figs. 4A, E–G). Carapace with strong marginal supraorbital spine, marginal antennal spine, pterygostomial angle with small spine, and low rounded suprabranchial ridge ( Figs. 4A–B).

Abdominal somites dorsally rounded. Somite 3 dorsally strongly hooded and curved, with rounded middorsal suggestion of ridge in posterior three-quarters. Pleura of somites 1–4 ventrally rounded, of somite 2 subcircular, of somite 4 elongate-oval; posteroventral angle of pleuron 5 acute. Somite 5 0.65 times length of somite 6. Somite 6 with posteroventral corner triangular. Telson dorsally gently convex, with proximal median cluster of fine setae on small ridge; with 5 pairs of dorsolateral spines, tapering to convex posterior margin bearing short outer and longer inner pairs of spines, with several simple fine setae between longer pair of spines ( Fig. 4B).

Cornea much wider than eyestalk, well pigmented.

Antennular stylocerite lanceolate, distally acute, extending well beyond distal margin of peduncular article 1; mesial and distal margins of article 1 bearing row of plumose setae; mesial margin with ventral spine at distal two-thirds; article 2 with mesial plumose setae and strong triangular spine at outer distal angle; article 3 with strong triangular spine directed anteriorly; inner flagellum slender, shorter than ventral flagellum; latter robust, tapering distally, of about 20 setigerous articles ( Fig. 4C).

Antennal scaphocerite with outer margin almost straight, ending in strong spine not extending beyond rounded distal margin of blade; latter widest at proximal third; antennal article 1 bearing strong ventral spine; flagellum missing from specimen ( Fig. 4C).

Mouthparts typical for the genus. Mandibular palp of 2 articles, article 2 slightly longer than article 1, with distal setae and row of lateral setae; mandibular incisor flattened, slender, tapering to acute apex, with 2 fine distal serrations; molar stout, grinding surface oblique-truncate ( Fig. 5C). Maxillule, maxilla, maxillipeds 1 and 2 little different from those figured for L. clarehannah ( Figs. 3D–G). Maxilliped 3 extending beyond scaphocerite by half length of distal article; distal article flattened, parallel-sided for most of its length, with 1 row of 20 corneous spines on mesial margin ( Fig. 4D).

Pereopod 1 reaching distal two-thirds of scaphocerite, robust; fingers slightly shorter than palm; corneous acute tip of fixed finger fitting between 2 corneous apical spines of dactylus. Pereopod 2 extending beyond scaphocerite by 1.75 times length of chela; carpus almost 1.75 times length of merus, of 7 articles; ischium slightly longer than merus ( Fig. 5A). Pereopod 3 over-reaching scaphocerite by half length of propodus plus dactylus; dactylus with corneous apical spine and 5 smaller spines on flexor margin; carpus slightly less than half length of propodus, unarmed; merus with distal spine on flexor margin, smaller spine at about distal twothirds. Pereopod 4 extending anteriorly slightly less than pereopod 3, of similar proportions to pereopod 3, with 1 distal spine. Pereopod 5 overreaching scaphocerite by length of dactylus; with 1 distal spine on outer surface of merus; carpus slightly less than half length of propodus and unarmed ( Fig. 5B).

Pereopods 1–5 each with 1 pleurobranch; epipod present on pereopods 1 and 2.

Uropodal peduncle with outer distal lobe apically narrowly rounded; exopod subequal in length than endopod, with fixed marginal tooth and movable spine at about distal three-quarters ( Fig. 4C).

Colour pattern. Carapace colour pattern pale with curved oblique scarlet stripes. Female holotype with 10 scarlet stripes broken into small scarlet spots, abdomen with scattered spots continuing on dorsal half of first three somites. Male paratype (NMV J58315 ) with 7 curved discontinuous stripes and broken into spots ventrally and across the crest, abdomen pink without scarlet spots on first three somites, tail-fan semitransparent. Bases of antennules and antennae, maxilliped 3 and pereopods orange-red; distal articles of appendages transparent pink ( Fig. 1A, B).

Distribution. North-western Australia continental slope, 9– 19°S, 397–458 m depth.

Etymology. From Latin crista (crest) and gallus (chicken), describing the shape of the distinctive rostral crest.

Remarks. Apart from the diagnostic features outlined above, L. cristagalli differs little from the full description given for L. clarehannah or the description of the similar L. yaldwyni ( Kensley et al. 1987) . It differs from these Australian species in colour pattern and in the shape and number of teeth of the carapace crest. Lebbeus cristagalli has a similar colour pattern to males of L. compressus from Japan but can be distinguished by the number of spines on maxilliped 3 ( Table 1). The high almost triangular carapace crest distinguishes L. cristagalli from the other Western Australian species, L. clarehannah , which has an evenly convex crest. The mandibular incisor was dissected from 3 specimens of L. cristagalli and had 2 or 3 distal serrations. This differs from the holotype of L. yaldwyni which is described with 4 or 5 serrations on the incisor.

The large type series provides information on intraspecific variation for L. cristagalli as summarised in table 1. The two photographed specimens have slightly different colour patterns ( Figs. 1A–B) but we do not believe these differences indicate separate species. One is a male and the other a female so it is possible that sexual dimorphism exists as in the case of L. compressus . Although variable, the carapace crest is consistently triangular ( Fig. 4A, E, F, G). Two paratypes have irregular dentition ( Figs 1A, 4F–G) and would appear to have been damaged in life.

An ovigerous female collected in the Timor Sea (NTM CR006897) may belong to another new species based on some differences in the size of teeth on the dorsal crest and colour pattern. The two anterior teeth of the dorsal crest are minute in this specimen but it is possible this is the result of damage in life. As revealed in a painting provided to us by A.J. Bruce, the carapace is pink with small scarlet spots on the dorsal half, the teeth of the crest are red on the dorsal half. Its general triangular shape agrees with L. cristagalli as do all other morphological characters.