Ampithoe tahue J. L. Barnard 1979

Ampithoe tahue

DIAGNOSIS OF FEMALE—Pleonal epimera 2–3 with small setule notch at posteroventral corner, no lateral ridges. Article 5 of gnathopod 1 shorter than article 6, posterior edge of article 5 with rounded-truncate lobe, palm oblique, gnathopod 2 especially stout, posterior lobe of wrist thin and elongate, hand tumid; article 2 of both gnathopods with anterodistal lobe laterally, not prominent on gnathopod 2. Article 2 of pereopods 1–2 about 2.6–2.8 times as long as broad. Ventral edge of article 1 on antenna 1 not spiniferous; peduncles of antennae 1–2 short, peduncle of antenna 2 stout, article 5 only 0.7 times as long as article 4, medial surfaces of articles 4–5 with weak conical protuberances, 2 or 3 cones on article 4, 2 on article 5, first article of flagellum elongate, with apicomedial cone and apicoposterior tooth, article 2 of flagellum very short but also with cone and tooth, flagellum only 7-articulate and about as long as article 5 of peduncle. Apical lobules of lower lip about equally short, bulbous, appressed. Coxa 1 produced forward. Peduncular process of uropod 1 vestigial. Rami of uropod 3 especially small. Article 2 of pereopods 4 and 5 weakly expanded, with protruding posteroventral corner. Telson ordinary.

MALE.—Unknown.

HOLOTYPE.—USNM 169016, female “c,” 4.01 mm (illus.).

TYPE-LOCALITY.—GAL 102, Galapagos Islands, Isla Santa Cruz, Academy Bay, 23 January, 1964, intertidal, from rocks in tidepool.

RELATIONSHIP.—This species is an apparent sibling of A. pollex Kunkel. The female is very similar to the female of A. pollex, especially in the critical features of lower lip and gnathopods but differs from that species in the shortened antennae, especially antenna 2, which resembles in rudimentary form the very stout antennae of the A. lindbergi group. In addition, the medial surfaces of articles 4–5 on the peduncle bear weak cone-teeth and article 1 of the flagellum on antenna 2 is elongate and also bears teeth. Uropod 3 is like that of male pollex with shortened rami. Gnathopod 2 is very tumid for a female of the genus.

DAW 27 has most males and females of the pollex form with thin bodies, thin antennae, but one stout female of A. tahue is present and one large stout male of this species with juvenoid gnathopod 2 like that of A. pollex is present. At 4.8 mm this stout male is significantly larger than the normal terminal males (about 3.5 mm) but lacks any of the modifications on the antennae of females of A. tahue and A. vacoregue except for the stoutness of antenna 2 and the relatively short flagellum. One might suggest that A. tahue and A. vacoregue are therefore simply aberrant super-females, though they bear normally setose brood plates and carry eggs.

MATERIAL.—GAL 102, 103; DAW 27, 40.

DISTRIBUTION.—Galapagos Islands, Isla Santa Cruz, Academy Bay, intertidal.