Acidostoma hancocki Hurley, 1963

Stoddart, H. E. & Lowry, J. K., 2012, Revision of the lysianassoid genera Acidostoma and Shackletonia (Crustacea: Amphipoda: Acidostomatidae fam. nov.), Zootaxa 3307 (1), pp. 1-34 : 8-9

Acidostoma hancocki Hurley, 1963

( Fig. 5 )

Acidostoma hancocki Hurley, 1963: 37 , figs 9, 10. ―J.L. Barnard, 1966a: 23. ― Austin, 1985: 602. ― Barnard & Karaman, 1991: 457. ― García-Madrigal, 2007: 91.

Acidostoma sp. ―J.L. Barnard, 1964: 229.

? Acidostoma hancocki . ―J.L. Barnard, 1966b: 66, fig. 13.

Material examined. One male, 5.4 mm, AM P.80161, coast of Orange County, California, USA, [approx. 34°N 118°30’W],? 93 m, February 1981, WLNG-Aurige Survey, stn FP6-1 .

Diagnostic description. Mandible molar a small non-setose triangular flap. Maxilla 1 palp absent. Maxilliped inner plate well developed; outer plate without subapical notch. Gnathopod 2 dactylus vestigial. Pereopods 5 and 6 merus about as long as broad. Epimeron 3 posteroventral corner produced into a spine. Uropod 1 peduncle dorsolateral margin with less than 10 robust setae. Uropod 2 peduncle dorsolateral margin not castellate, without setae. Uropod 3 reaching to about the end of the peduncle of uropod 2; rami shorter than peduncle, without plumose setae; outer ramus article 2 small. Telson broader than long, moderately cleft (about 50%).

Remarks. The collection label for the material recorded here notes “red eyes” but there is no eye apparent on the specimen, only a small round area of cuticle that is slightly clearer than the cuticle on the rest of the head. It seems that the eyes fade in alcohol and cannot be used as a reliable species character unless fresh material is available.

Acidostoma hancocki has been described as having the peduncle of uropod 3 “laterally expanded upwards in a rectangular wing” ( Hurley 1963: 40) or “plate-like” ( Barnard & Karaman 1991: 457). However, it seems that the labelling of uropods 2 and 3 were reversed on Hurley’s figure 9; the peduncle of uropod 2 is expanded, as in all other species of Acidostoma , and as shown on Hurley’s whole-animal figure.

Hurley (1963: 37) noted, as a species diagnostic character for A. hancocki , the presence of a “stout bladelike spine on inner distal angle” of the first article of antenna 1 flagellum. We have found robust setae on the primary and accessory flagella of all male Acidostoma we have examined. It is not indicated in Hurley’s report whether the antenna 1 depicted in fig. 9 is that of a male or a female. Considering the development of the callynophore in the male A. hancocki reported here, Hurley’s figure would appear to be of a female. If so, the species may be unusual in having robust setae on the antenna 1 of the female. The only acidostomatid species we have seen with robust setae on the female antenna 1 is S. robusta .

J.L. Barnard (1966b) recorded three specimens of A. hancocki from southern California. One specimen, a juvenile of 1.8 mm, has a small but distinct palp on maxilla 1. Hurley (1963) described the palp as “not seen”. The material from southern California which we have examined has no palp. Barnard’s material is from much deeper water than is the type material recorded by Hurley; it may represent another species.

Distribution. Southern California, USA, eastern North Pacific Ocean; 22–73 m depth, possibly to 672 m.

Figures

FIGURE 5. Acidostoma hancocki Hurley, male, 5.4 mm, AM P.80161, Orange County, California, USA.