Heteralepas microstoma

Heteralepas microstoma (Gruvel, 1901)

Alepas microstoma Gruvel, 1901: 259; 1902a: 282, pl. 24, figs 1, 7, 8; 1905: 162, fig. 180.

Heteralepas microstoma – Krüger 1911: 29. — Zevina 1982: 118, fig. 104. — Young 1998a: 10, figs 6, 7; 1998b: 33. — Southward 1998: 17, fig. 1.

Heteralepas meteorensis Carriol, 1998: 506, fig. 1.

MATERIALEXAMINED. — SEAMOUNT 2, stn CP 138, 30°01.94’N, 28°29.00’W, 300 m to 30°01.98’N, 28°27.81’W, 310 m, 1 specimen, tl 4.2 mm (MNHN Ci 2822). — Stn CP 142, 30°02.95’N, 28°29.42’W, 302 m to 30°02.96’N, 28°28.21’W, 310 m, 7 specimens, tl 4.5-22.0 mm (MNHN Ci 2823, MNRJ 13885). — Stn CP 177, 29°58.43’N, 28°38.09’W, 315 m to 29°56.51’N, 28°38.57’W, 7 specimens, tl 18.4-25.3 mm (MNHN Ci 2824, MNRJ 13886).

REMARKS

Heteralepas microstoma is commonly found in the Azores and Madeira Archipelagos, and the Great Meteor Seamounts, occurring between depths of 269 and 623 m. The present samples, from the Meteor and Atlantis Seamounts, were dredged between 300 and 315 m. Young (1998a) suggested a depth preference of about 300 m for this species. Carriol (1998) described Heteralepas meteorensis from the Meteor Bank. The characters he used to diagnosis that species are a peduncle longer than the capitulum, the capitulum lacking scuta, and a carinal crest, without protuberances, continuous on the peduncle. The length of the peduncle used to separate species by Zevina (1982: 106) is not a stable character. Gruvel (1902a) only cited one measurement for his specimens and in this specimen the length of the capitulum and peduncle was similar. Young (1998a) studied more than 1000 specimens of H. microstoma, that were usually found in clusters attached to the substrate, and the length of their peduncles varied from the length of the capitulum to three times its length. The aggregated habit of some species of Heteralepas results in a large variability in the peduncle length. Specimens occupying the central position in a cluster have their peduncles longer than those growing marginally. Also, the carinal crest, lacking protuberances is common to H. microstoma. The presence of a scutum in the Heteralepadidae remains controversial. Some authors have described a degenerated scutum on the capitulum, but it appears only to be a thickening of the cuticle in the area of attachment of the adductor muscle and is not directly related to the presence of a scutum. Gruvel (1902a) described H. microstoma as lacking scuta and having a dorsal crest. Therefore, the maintenance of Heteralepas meteorensis Carriol is not justified, and it is considered a junior synonym of H. microstoma.