Alijinocaris lusca, Williams and Chace, 1982

Komai, Tomoyuki & Segonzac, Michel, 2005, A revision of the genus AlIJinocaris Williams and Chace (Crustacea: Decapoda: Caridea: Alvinocarididae), with descriptions of a new genus and a new species of AlIJinocaris, Journal of Natural History 39 (15), pp. 1111-1175 : 1124-1127

AlIJinocaris lusca Williams and Chace, 1982

( Figures 4 , 5 , 29 )

Alυinocaris lusca Williams and Chace 1982, p 137 , Figures 1–7 [type locality: Rose Garden area, Galapagos Rift, 00 ° 48.159N, 86 ° 13.299W, 2450 m]; Shank 1997, p 191; Shank et al. 1999, p 246 (Table 1), Figure 2 .

Not Alυinocaris lusca: Fustec et al. 1987, p 129 .5 Lebbeus carinatus de Saint Laurent, 1984 (not Lebbeus carinatus Zarenkov, 1976 ).

Material examined

Galapagos Rift. DS Alυin: dive 990, Rose Garden area , 00 ° 48.159N, 86 ° 13.299W, 2450 m, 9 December 1979, one male CL 7.2 mm, 10 females CL 7.1–13.5 mm (paratypes; USNM 184537 ) .

Description

Body moderately robust.

Rostrum ( Figure 4C ) slightly descending or directed forward, straight, 0.37–0.44 times carapace length, usually reaching second segment of antennular peduncle, but rarely not exceeding first segment; dorsal margin with slightly convex or straight general outline, armed with 10–14 teeth including four to six moderately large teeth on carapace posterior to orbital margin, posteriormost tooth arising from 0.32–0.39 of carapace length; ventral margin armed with three or four small teeth on anterior 0.20–0.40. Carapace ( Figure 4 A– D) width 0.55–0.67 of length; postrostral median ridge relatively low, extending to 0.60– 0.70 of carapace length, dorsal angle about 170 °; pterygostomian tooth weakly produced anteriorly, smaller than antennal tooth, at most only slightly reaching beyond antennal tooth; post-antennal groove very shallow; branchial region not particularly inflated.

Third abdominal pleuron unarmed marginally. Fourth abdominal pleuron ( Figure 4E ) with one to five (most frequently four) posterolateral teeth. Fifth abdominal pleuron similarly armed with strong posteroventral tooth and additional one to five small teeth. Sixth somite 1.50–1.70 times longer than height. Telson ( Figure 5A ) not reaching to slightly overreaching posterior margin of uropodal endopod, very slightly narrowed posteriorly, length 3.20–3.30 times anterior width and 4.10–4.30 times posterior width; armed with seven to nine dorsolateral spines; posterior margin ( Figure 5B, C ) shallowly notched medially or slightly convex, armed with six to nine pairs of spines (mesial four to seven spines unequal in length) and one or two short plumose setae on either side of median notch.

Antennular peduncle ( Figure 4B ) moderately stout, second segment 2.00–2.20 times longer than wide. Antennal scale ( Figure 5D ) about half length of carapace, 2.20–2.60 times longer than wide; lateral margin slightly convex to straight, subparallel with dorsal median ridge; distolateral tooth relatively narrow, directed forward, not reaching distal margin of somewhat produced, rounded blade.

First pereopod as illustrated ( Figure 5E ); palm ( Figure 5F ) at most 1.26 times longer than height; dactylus longer than palm. Third pereopod ( Figure 5G ) relatively slender for genus; dactylus ( Figure 5H ) with accessory spinules notably increasing in size distally; carpus 0.70–0.75 times as long as propodus; merus about 8.00 times as long as greatest height.

Size

Largest male 7.3 mm; largest female 13.5 mm, ovigerous females unavailable. Maximal TL ca 85 mm.

Variation

As is apparent from the above description, the shape of the posterior margin of the telson is variable from shallowly notched medially to weakly convex.

Distribution and habitat

Known with certainty only from the Galapagos Rift, Rose Garden area, 00 ° N, 2450 m, and

Figures

Figure 1. Diagrammatic Alυinocaris, showing measurements used in text. (A) Carapace and rostrum, lateral; CL, carapace length; DA, dorsal angle; RL, rostral length. (B) Carapace, dorsal: CW, carapace width. (C) Anterior part of carapace and cephalic appendages, dorsal; L, length; W, width. (D) Sixth abdominal somite, lateral; L, length; H, height. (E) Telson, dorsal; AW, anterior width; L, length; PW, posterior width. (F) Antennal scale, dorsal; abbreviations as in (C). (G) Chela of first pereopod, lateral; PL, palm length; PH, palm height.

Figure 2. Alυinocaris muricola Williams, 1988. Left appendages. (A) Antennal scale, dorsal; (B) mandible, dorsal; (C) maxillule, ventral; (D) maxilla, ventral; (E) first maxilliped, ventral; (F) endopod of first maxilliped, dorsal; (G) second maxilliped, ventral; (H) first pleopod, ventrolateral; (I) endopod of first pleopod; (J) appendices interna and masculina of second pleopod, mesial. (A–H) Female from Régab site, west equatorial African margin (CL 16.8 mm; MNHN-Na 14277); (I, J) male from same locality (CL 15.4 mm; Ifremer).

Figure 3. Alυinocaris muricola Williams, 1988. Left thoracic appendages. (A) Third maxilliped, lateral; (B) coxa and antepenultimate segment of third maxilliped, dorsal; (C) first pereopod, lateral; (D) carpus of first pereopod, mesial; (E) second pereopod, lateral; (F) chela of second pereopod, dorsal; (G) third pereopod, lateral; (H) dactylus of third pereopod, lateral; (I) fourth pereopod, lateral; (J) fifth pereopod, lateral; (K) dactylus of fifth pereopod, lateral. Female from Régab site, west equatorial African margin (CL 16.8 mm; MNHN-Na 14277).

Figure 4. Alυinocaris lusca Williams and Chace, 1982. (A) Carapace and cephalic appendages, lateral (rostrum broken off); (B) anterior part of carapace and cephalic appendages, dorsal; (C) same, lateral; (D) carapace, dorsal (rostrum broken off); (E) third to sixth abdominal somites, lateral. (A, B, D, E) Paratype female from Rose Garden area, Galapagos Rift (CL 13.5 mm; USNM 184537); (C) paratype female (CL 8.6 mm; same lot).

Figure 5. Alυinocaris lusca Williams and Chace, 1982. (A) Telson and right uropod, dorsal; (B, C) posterior part of telson, dorsal; (D) right antennal scale, dorsal (marginal setae omitted); (E) first pereopod, lateral; (F) chela of first pereopod, outer; (G) left third pereopod, lateral; (H) dactylus and distal part of propodus of left third pereopod, lateral. (A, B, D–H) Paratype female from Rose Garden area, Galapagos Rift (CL 13.5 mm; USNM 184537); (C) paratype (CL 8.6 mm; same lot).

Figure 6. Alυinocaris markensis Williams, 1988. (A) Carapace and cephalic appendages, lateral; (B) anterior part of carapace and cephalic appendages, dorsal; (C) carapace, dorsal; (D) third to sixth abdominal somite, lateral; (E) telson and right uropod, dorsal; (F) posterior part of telson, dorsal. Female from site Les Ruches, Snake Pit, Mid-Atlantic Ridge (CL 16.7 mm; MNHN-Na 14282).

Figure 7. Alυinocaris markensis Williams, 1988. (A) Left antennal scale, dorsal; (B) left first pereopod, lateral; (C) chela of left first pereopod, outer; (D) left third pereopod, lateral; (E) dactylus and distal part of propodus of left third pereopod, lateral. Female from site Les Ruches, Snake Pit, Mid-Atlantic Ridge (CL 16.7 mm; MNHN- Na 14282).

Figure 29. Distribution map of Alυinocaris species known at present.