Aplidium antillense ( Gravier, 1955 )

Fortaleza, Maria Tarciana Vieira & Lotufo, Tito Monteiro Da Cruz, 2018, Polyclinidae (Ascidiacea: Aplousobranchia) from the Gulf of Mexico, collected during the “ Hourglass ” cruises (1965 - 1967), Zootaxa 4422 (4), pp. 519-536 : 521

Aplidium antillense ( Gravier, 1955)

( Figures 2, 3)

Amaroucium antillense Gravier, 1955: 618 .

Aplidium antillense Sanamyan and Gleason, 2009: 51 (and synonymy). Rocha et al, 2012: 19. Examined material: collected in 6/1/1967, 27°37’N, 083°07’W, 18.3m, specimen # EJ-67-7.

Description: Colony is lobular and laterally flattened, 2.0 cm high, attached to the substrate by a narrow base (0.5 cm thick). Tunic translucent and gelatinous. Presence of marked depressions on the colony surface and fine sediment next to the base. Zooids yellowish, visible through the tunic, not organized in systems.

Zooids with approximate total length of 5.25 mm; post-abdomen of variable size (length range – thorax and abdomen = 1.66 – 2.24 mm; post-abdomen = 0.96 – 5.76 mm). Branchial siphon tubular, measuring 0.11–0.16 mm, with six well-defined lobes. Atrial aperture small with smooth edges, located at the level of the third stigmata row; atrial languet simple, up to 0.32 mm long. Musculature conspicuous, formed by 15 to 20 thin parallel longitudinal bundles on each side of the zooid. Pharynx with 12 or 13 rows of stigmata. The number of stigmata per row could not be counted. Esophagus short. Stomach elongated or slightly flattened in the anterior and posterior ends, with 10 to 11 continuous longitudinal folds. The size of the stomach and esophagus together are equal to about half the length of the abdomen. The intestine is divided into three parts due to the presence of a posterior stomach and the strong constriction between the medium intestine and the rectal valve discernible in some zooids. The anal opening is located at the level of the eighth stigmata row. Abdomen and post-abdomen not divided by a constriction. Gonads, embryos or larvae are absent.

Remarks. According to the original description of Aplidium antillense , the main diagnostic characters of the species were 12 rows of stigmata in the pharynx, stomach with 12 to 14 longitudinal folds, intestine divided into three parts, and well-defined post-abdomen ( Gravier, 1955). Later, other authors described some variations in these characters, such as pharynx with 10 to 13 rows of stigmata, and stomach with 10 to 14 folds ( Monniot, 1972; Monniot, 1983; Sanamyan & Gleason, 2009). In spite of the state of the colony and the lack of information on living coloration, we are confident of the identification of this material because the characteristics match the previous descriptions for the species.