Aclis watsoni Barros, Lima & Francisco, 2007

Fig. 4

Aclis watsoni Barros, Lima & Francisco, 2007: 65, Fig. 7–9: Rios (2009: 198, Fig.491); Cavallari et al. (2016: 52).

Type material. Holotype (herein examined): MZSP 77991; R/V Natureza coll., 28/x/2000 . Paratypes (herein examined): Brazil: Sergipe state: type locality; MZSP 77992 [3]; Revizee Nordeste; 11°35′30″, 37°12′18″W, 510 m; R/V Natureza col., 30/x/2000: MZSP 77993 [4].

Type locality. Brazil: Sergipe state; Revizee Nordeste, 10°41′24″S, 36°18′42″W, 365 m.

Material examined. The types and: Brazil: Sergipe state: MARSEAL SED 3 sta. HN4; CZUFS GAS-00105 [1].

Measurements. Holotype, MZSP 77991: 7 whorls; SL= 4.29 mm; BWL= 1.72 mm; AL= 1.02 mm; SW= 1.44 mm; AW= 0.86 mm. Paratype MZSP 77993: 7 whorls; SL= 4.26 mm; BWL= 1.73 mm; AL= 1.02 mm; SW= 1.5 mm; AW= 0.89 mm.

Remarks. Aclis watsoni has been reported only on the coast of northeastern Brazil, based on few specimens. We report new material from the same region, which consists of a single shell with a worn surface but still exhibiting the strong spiral keels.

Aclis watsoni closely resembles A. sarissa (Figs 2–3) in the general shape and dimensions of the shell. However, the holotype and paratype figured by Barros et al. (2007: Fig. 7–9) have a remarkable spiral sculpture since the third teleoconch whorl, which gives a truncated outline in the teleoconch whorls. The types of A. sarissa (Fig 2) have a more rounded outline, with a weaker spiral sculpture usually notable in the last teleoconch whorls. In view of the preservation status of the type series of A. sarissa and the possible variation in the expression of the spiral keels, one could suspect a possible synonymy of A. sarissa and A. watsoni, in which the types of A. sarissa would be eroded specimens. Additional specimens would be necessary to confirm the synonymy.

Aclis watsoni resembles Aclis eolis Bartsch, 1947 (Fig. 19A–D), from Florida, but differs by the more truncated outline of the teleoconch whorls. Furthermore, A. watsoni can be distinguished from A. eolis by the pattern of the teleoconch sculpture, the former has a single and pronounced spiral keel in the posterior whorls and reaches three pronounced spiral keels at the anterior whorls. All spiral keels are restricted to the lower half region of the whorls. In contrast, A. eolis has three weak spiral keels since the initial teleoconch whorls that are distributed through the whole surface of each whorl, equally spaced (Bartsch 1947) (Fig. 19A–D).

Geographic Distribution. Brazil: Sergipe state. From 365 m to 510 m.