Lebbeus acudactylus, Jensen, Gregory C., 2006

Jensen, Gregory C., 2006, Three new species of Lebbeus (Crustacea: Decapoda: Hippolytidae) from the Northeastern Pacific, Zootaxa 1383, pp. 23-43 : 34-38

Lebbeus acudactylus new species

Figs. 4 D, 7–9

Type Material: Holotype female, postorbital carapace length 9.6 mm; with bopyrid parasite. Aleutian Islands, Alaska (51.86° N, 174.92°W), trawl, 155 m. 13 June 2000. K.P. Maslenikov collector. National Museum of Natural History, Smithsonian Institution, USNM 1092260. Also allotype, 9.0 mm, with bopyrid parasite, Gulf of Alaska (56.12° N, 157.76°W), trawl, 166 m. 12 June 2005. K.P. Maslenikov, collector, USNM 1092261. Paratype female, 7.1 mm, Aleutian Islands, Alaska (52.28°N, 174.76°W), trawl, 163 m. 15 June 2000. K.P. Maslenikov collector. California Academy of Sciences ( CASIZ 174053).

Description: Integument smooth, somewhat thick. Rostrum moderately long, horizontal, 0.45–0.60 carapace length ( Fig. 8 A); greatly exceeding cornea and basal article of antennular peduncle and sometimes exceeding second article. Carapace and rostrum with 4–5 dorsal teeth, three postorbital; rostrum with 1–3 ventral teeth. Supraorbital spine moderate; suborbital and antennal spines strong, pterygostomian spine distinct.

Abdomen smooth. Pleura of abdominal somites 1–4 rounded; pleura of fourth and fifth abdominal somites with posteroventral spines. Telson 1.5–1.6 times length of sixth somite, with 3–4 pairs of dorsolateral spinules and 14–15 terminal spinules ( Fig. 9 E).

Eye diameter 0.17–0.2 carapace length; cornea pigmented and slightly dilated; ocellus present.

Basal article of antennular peduncle ( Fig. 9 A) with one distal, dorsal spine and a strong subdistal, ventromesial spine; stylocerite barely exceeding basal article or reaching to middle of second article of antennular peduncle. Second article with large dorsolateral spine on distal margin; third article with dorsal spine. Dorsolateral flagella with 15–23 thickened segments; distal portion slender, with at least 5 segments; tip of ventromesial flagella broken but probably subequal to dorsolateral flagella.

Basicerite of antenna with rounded dorsal lobe and strong ventrolateral spine; carpocerite reaching third article of antennular peduncle. Antennal scale 2.5 times longer than wide and about 0.7 carapace length; lateral margin straight; lamella exceeds spine. Antennal flagellum about 3.6 times carapace length.

Left mandible ( Fig. 8 B) with sparsely setose, two-segmented palp; incisor broad, with 6 small, uniform teeth and larger distal tooth. Left molar large, subcylindrical, with large distal tooth. Right molar not dissected.

First maxilla ( Fig. 8 C) with shallowly bilobed palp, lobes each tipped with a stout seta. Distal endite oval, bearing many plumose setae; proximal endite with long, stout setae.

Second maxilla ( Fig. 8 D) with palp tipped by two setae. Basal endite bilobed, mesial margin densely setose. Coxal endite damaged in dissection, bearing long, plumose setae. Scaphognathite densely fringed with plumose setae, longest anteriorly and anteromesially and along posterolateral margin. Anterior lobe of scaphognathite long, subrectangular; posterior lobe rounded.

First maxilliped ( Fig. 8 E) with two-segmented palp, distal article subequal to proximal. Caridean lobe well developed and fringed with long plumose setae. Exopod long, tipped with setae. Endites well-developed, densely setose on mesial margin. Epipod large, bilobed.

Second maxilliped ( Fig. 8 F) with ultimate article densely setose on mesial margin; penultimate article with many long setae. Exopod well developed, tipped with long setae. Epipod kidney shaped, with small podobranch.

Third maxilliped ( Fig. 8 G) exceeding end of antennal scale by about half the length of the ultimate article and tipped with nine apical and subapical corneous spinules; mesial margins of ultimate and penultimate articles densely setose. Penultimate article about 0.23 of ultimate; antepenultimate article with small, subdistal, ventrolateral spinule. Hooked epipod present.

Pereopods 1–5 with pleurobranchs. First pereopods ( Fig. 9 B) equal, chelate. Dactyl 0.36–0.45 propodus length; propodus 3.6–4.0 times as long as wide and 0.44–0.48 carapace length. Antennal cleaning brushes on propodus and carpus. Carpus 1.5–2.5 times as long as wide; merus 3.1–4.2 times longer than wide and 1.6–1.8 times longer than carpus. Coxa with hooked epipod and setobranch.

Second pereopod equal, chelate, exceeding antennal scale by slightly more than palm; dactyl 0.40–0.45 propodus length. Carpus with 7 segments, third from merus longest. Merus 0.57–0.67 carpus length. Coxa with hooked epipod;setobranch greatly reduced or absent.

Third pereopod dactyl ( Fig. 9 C) with corneous, bifid tip preceded by 3–5 spinules on flexor margin. Propodus 8.9–9.9 times longer than wide; females with about 25 small spinules along flexor margin and male with about 40, as a single row proximally and in two indistinct rows distally. Carpus 2.5–2.8 times as long as wide. Merus 6.2–7.1 times long as wide, with 3–4 lateral spinules that increase in size distally. Fourth and fifth pereopods similar to third but decreasing in size; fourth with 3–5 meral spinules; fifth with 3–4 spinules and propodal grooming brush.

Endopod of first pleopod of female about two-thirds length of exopod. Endopod of first pleopod of male triangular, flat, subequal to exopod and fused with appendix interna; lateral margin with long setae, mesial margin with short, curved setae; distal one-fifth a fingerlike appendix interna tipped with cincinnuli. Appendix masculina ( Fig. 9 D) stout; tipped with several long spinules and subequal in length to appendix interna.

Color: Carapace and abdomen marked with bright yellow bands with red margins ( Fig. 4 D). First carapace band somewhat oblique, angling back from behind orbit; second band (not visible in photograph due to bopyrid) at rear of carapace. First band on abdomen at third segment, second band crossing bases of uropods. Distal half of telson yellow, as are the eyestalks and the lateral flagella of the first antennae. Walking legs unbanded, pink; antennal flagellum clear with dark red bands.

Distribution: So far this species is only known from the Aleutian Islands and the Gulf of Alaska, at depths of 150– 170 m.

Etymology: The specific name refers to the bifid dactyls of the walking legs, in which the terminal spine is unusually long and sharp.

Figures

FIGURE 8. Lebbeus acudactylus. A, G: female holotype; B – F: female paratype. A, anterior region of carapace; B, left mandible; C, first maxilla; D, second maxilla; E, first maxilliped; F, second maxilliped; G, tip of third maxilliped.

FIGURE 9. Lebbeus acudactylus. A, E: female holotype; B, C: female paratype; D: male allotype. A, anterior region in dorsal view; B, chela of first pereopod; C, dactyl of third pereopod; D, appendix masculina and appendix interna; E, tip of telson.

FIGURE 4. A, aquarium photo of Lebbeus eludus showing daytime coloration; B, in situ photo of L. eludus at night; C, in situ photograph of L. mundus; D, photograph of freshly-caught holotype of L. acudactylus. A – C by G. C. Jensen; D by K. P. Maslenikov.