Alijinocaris aeilliamsi, Shank and Martin, 2003

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 : 1155-1158

publication ID	https://doi.org/ 10.1080/00222930400002499
persistent identifier	https://treatment.plazi.org/id/050D1914-FFE5-FF80-FEB5-FD31FE0E4932
treatment provided by	Carolina
scientific name	Alijinocaris aeilliamsi
status

Treatment

AlIJinocaris aeilliamsi Shank and Martin, 2003

( Figures 23 View Figure 23 , 24 View Figure 24 , 29 View Figure 29 ) Alυinocaris n. sp. 2: Shank et al. 1999, p 246, Table 1. Alυinocaris aeilliamsi Shank and Martin 2003, p 159 , Figures 1–3 View Figure 1 View Figure 2 View Figure 3 .

Material examined

Mid-Atlantic Ridge. Saldanha: dive 1274, Menez Gwen, 37 ° 51.609N, 33 ° 31.359W, 865 m, 15 July 1998, SMAC tray, one female CL 14.4 mm (MNHN-Na 15056) GoogleMaps .

Diva 1: dive 14, Menez Gwen, 37 ° 50.469N, 31 ° 31.359W, 845 m, 22 May 1994, one female CL 8.0 mm (MNHN-Na 15057); same data, one male CL 4.6 mm, one female CL 6.3 mm ( CBM) GoogleMaps .

Diva 2: dive 12, Menez Gwen, 37 ° 50.549N, 31 ° 31.309W, 866 m, 14 June 1994, slurp gun, one juvenile CL 3.5 mm (MNHN-Na 15058); dive 13, same site, 15 June 1994, one female CL 8.1 mm (MNHN-Na 15059); dive 14, same site, 19 June 1994, one male CL 6.1 mm (MNHN-Na 15060); dive 16, same site, 22 June 1994, slurp gun, three females CL 5.0– 8.8 mm (including one ovigerous CL 5.8 mm) (MNHN-Na 15061); dive 26, same site, 2 July 1994: one male CL 5.0 mm (MNHN-Na 15062).

Description

Body most robustly built among species of Alυinocaris presently known.

Rostrum ( Figure 23A, B View Figure 23 ) directed forward, straight, 0.27–0.37 of carapace length, slightly falling short of or slightly overreaching distal margin of first segment of antennular peduncle; dorsal margin armed with 10–15 teeth, including five to nine teeth on rostrum proper and four to eight small to moderately large teeth on carapace posterior to orbital margin, posteriormost tooth arising from 0.13–0.20 of carapace length; ventral margin always unarmed. Carapace ( Figures 23A View Figure 23 , 24A View Figure 24 ) about 0.70 times as wide as long; postrostral median ridge relatively low, only weakly compressed laterally, extending to midlength of carapace, with dorsal angle 150 °; pterygostomian tooth somewhat produced anteriorly, subequal in size to antennal tooth, projecting distinctly beyond antennal tooth; post-antennal groove obsolete; branchial region not inflated.

Third abdominal pleuron unarmed. Fourth abdominal pleuron ( Figure 23C View Figure 23 ) rounded or with small posteroventral tooth. Fifth abdominal pleuron armed with strong posteroventral tooth and two to four additional tiny teeth on posterior margin. Sixth abdominal somite 1.10–1.20 times longer than height. Telson ( Figure 23D View Figure 23 ) not reaching posterior margin of uropodal endopod, length 2.20–2.30 times as long as anterior width and 3.10–4.00 times as long as posterior width; armed with six or seven dorsolateral spines arranged in straight or slightly convex line; posterior margin ( Figure 23E View Figure 23 ) broadly rounded (occasionally with shallow median notch), armed with two pairs of lateral spines and 14–16 plumose setae all longer than mesial pair of lateral spines.

Antennular peduncle ( Figure 23B View Figure 23 ) very stout, second segment 1.05–1.11 times longer than wide. Antennal scale ( Figure 23B View Figure 23 ) 0.40–0.43 times as long as carapace, 1.40–1.50 times longer than wide; lateral margin straight or convex; distolateral tooth broad, directed forward, not reaching broadly rounded distal margin of blade.

First pereopod ( Figure 24B View Figure 24 ) as illustrated; greatest height of palm at most 0.50 times length of chela ( Figure 24C View Figure 24 ); dactylus ( Figure 24C View Figure 24 ) subequal in length to palm. Third pereopod ( Figure 23D View Figure 23 ) relatively stout; dactylus ( Figure 24E View Figure 24 ) with accessory spinules notably increasing in size distally; carpus 0.65 times as long as propodus; merus about 5.50 times as long as greatest height.

Size

Largest male CL 6.1 mm; largest female 10.3 mm, ovigerous female 5.8 mm.

Distribution and habitat

Known only from hot vents at Menez Gwen site on the Mid-Atlantic Ridge ( Figure 29 View Figure 29 ), at depth of 850–865 m. It was difficult to find shrimps from the submarine or image on the video tapes, but the specimens used in this study were collected from the mussel beds of the mytilid Bathymodiolus azoricus Cosel, Comtet and Krylova, 1999 .

Remarks

Alυinocaris aeilliamsi is clearly distinguished from most others in the genus by the robust body, relatively short rostrum usually unarmed on the ventral margin, relatively low postrostral median ridge on the carapace reaching only to the midlength of the carapace, the posteriormost median tooth on the carapace arising from the anterior 0.13–0.20 of the carapace, broad telson and very stout antennular peduncle. Two other species of Alυinocaris also have similarly short rostra with ventral margins unarmed or armed only with one tooth, A. stactophila and Alυinocaris sp. 1. However, the latter two differ from A. aeilliamsi in the less robust body, narrower telson and more slender antennular peduncle. The presence of a row of plumose setae on the posterior margin of the telson, instead of a row of spines, distinguishes A. aeilliamsi from A. stactophila .

Some of the characters mentioned above are useful in discriminating juveniles of A. aeilliamsi from those of the other species. These include the relatively robust sixth abdominal somite (1.30 times as long as high versus 1.40 or more times as long) and more stout second segment of the antennular peduncle (about 1.30 times as long as wide versus more than 1.50 times as long).