Lebbeus clarehannah, 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 : 127-131

Lebbeus clarehannah sp. nov.

( Figs. 1C, 2, 3)

Lebbeus sp. MoV 5425. — Poore, McCallum & Taylor 2008: 84.

Material examined. Holotype. Western Australia, off Bald Island (35°12.49'S 118°39.04'E – 35°12.14'S 118°40.08'E), 408–431 m, beam trawl, R. Wilson et al. on FRV Southern Surveyor , 24.XI.2005 (stn SS10- 2005 034), WAM CR40055 (female, pocl 10.0 mm).

Diagnosis. Carapace high-crested, evenly convex in profile, with 10 forwardly directed teeth on rostrum and anterior half of carapace. Rostrum a continuation of carapace crest, reaching almost to distal margin of first antennular article, apex acutely triangular with tubercle ventral to apex. Mandibular incisor with 2 fine distal serrations. Maxilliped 3 with 23 corneous spines ( Fig. 2D). Pereopods 1 and 2 with epipods. Colour pattern, see description below ( Fig. 1C).

Description of holotype. Carapace high-crested, evenly convex in profile, with 10 forwardly directed teeth on rostrum and anterior half of carapace. Rostrum a continuation of carapace crest, reaching almost to distal margin of first antennular article, apex acutely triangular with tubercle ventral to apex. Carapace with strong marginal supraorbital spine, marginal antennal spine, pterygostomial angle with small spine, and low rounded suprabranchial ridge ( Figs. 2A–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 0.75 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 4 (right) and 5 (left) 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. 2C).

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 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. 2B).

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. 2B).

Mouthparts typical for the genus. Mandibular palp of 2 articles, article 2 slightly longer than article 1, with distal setae and 1 lateral seta; mandibular incisor flattened, slender, tapering to acute apex with 2 fine distal serrations; molar stout, grinding surface oblique-truncate ( Fig. 3C). Maxillule, maxilla, maxillipeds 1 and 2 as figured ( 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 23 corneous spines on mesial margin ( Fig. 2D).

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 ( Figs. 2E–F). Pereopod 2 extending beyond scaphocerite by 1.75 times length of chela; carpus 1.75 times length of merus, composed of 7 articles; ischium slightly longer than merus ( Fig. 3A). Pereopod 3 dactylus and propodus missing; carpus unarmed; merus with distal spine on outer surface. Pereopods 4 missing. 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, propodus blade-like, not cylindrical ( Fig. 3B).

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 to endopod, with fixed marginal tooth and movable spine at about distal three-quarters ( Fig. 2C).

Colour pattern. Carapace pale yellow, anteriorly fading to green at dorsal posterior half, and covered in scarlet spots arranged in 5 curved oblique lines, more scattered on crest. Abdomen pink, with 2 vertical rows of scarlet spots on each of somites 1 and 2, and 1 row and few scattered spots on somite 3. Tail fan semitransparent. Bases of antennules and antennae, maxilliped 3 and pereopods orange tinted and speckled ( Fig. 1C).

Distribution. South-western Australia continental slope, 408–431 m depth (known only from type locality).

Etymology. This species is named after Clare Hannah Longley for her love of Western Australia’s ocean, and her contribution to its conservation; used as a noun in apposition.

Remarks. Lebbeus clarehannah belongs in the group of species of Lebbeus with epipods present on pereopods 1 and 2. It closely resembles the other three crested species discussed in this paper but can be differentiated by the shape of the dorsal crest, number of spines on maxilliped 3 and colour pattern as outlined in Table 1. Lebbeus compressus has only 8−10 corneous spines on maxilliped 3 while the specimen of L. clarehannah has 23 spines. L. clarehannah also has more teeth on the dorsal crest than L. compressus . Its unique colour patttern distinguishes it from the south-eastern Australian L. yaldwyni which has stripes rather than rows of spots. Differences from L. cristagalli are discussed below.