Dushia atra (Girard, 1851)

Gonzalez-Cueto, Jaime, Quiroga, Sigmer & Norenburg, Jon, 2014, A shore-based preliminary survey of marine ribbon worms (Nemertea) from the Caribbean coast of Colombia, ZooKeys 439, pp. 83-108 : 90

Taxon classification Animalia Heteronemertea Lineidae

Dushia atra (Girard, 1851) Fig. 2 F–I

Description.

Fifteen specimens up to about 160 mm long, 2.5 mm wide; dorsoventrally flattened; head elongate, can be pointy; short, slender caudal cirrus present. Black body, lips of cephalic furrows, tip of head and tail grayish or milky white. Deep cephalic furrows form lateral margins of head. Ocelli lacking. Mouth ventral, a large longitudinal slit posterior to cephalic furrows. Proboscis long, yellow, with smooth surface when everted.

Distribution.

Curaçao ( Corrêa 1963), Gulf of Mexico ( Norenburg 2009); Santa Marta.

Comments.

This was the most frequently found species, though not necessarily the most abundant; we did not do quantitative sampling in this study. Given the wide regional distributions of other nemerteans in this and other recent studies (e.g., Corrêa 1961, 1963; Norenburg 2009) one expects such a common species to be identifiable as a regionally known species. Many of the early descriptions, however, are based on highly contracted and, often, fragmented specimens and lack observations from life (e.g., Verrill 1900; Coe 1901; Stiasny-Wijnhoff 1920). Presence or absence of a caudal cirrus is unreliably known for several named species from the region that are more or less blackish. The genera Cerebratulus and Micrura , both considered to have a caudal cirrus as a matter of diagnosis, are known among nemertean specialists to be fraught with taxonomic inconsistencies (see, e.g., Schwartz and Norenburg 2001, 2005). The presence or absence of a caudal cirrus seems, based on DNA data, to be an unreliable diagnostic for those genera ( Schwartz 2009). Possible Caribbean options for our species include Cerebratulus leucopsis ( Coe 1901), reported to have a caudal cirrus, and Corsoua kristenseni Corrêa, 1963, reported to lack a caudal cirrus. We believe that the former may be synonymous with Dushia atra sensu Corrêa (1963) from Curaçao. Corsoua kristenseni has a small mouth and occurs in mangrove habitat, whereas Dushia atra sensu Corrêa (1963) has a large mouth and occurs at the high-water line in clean sand under rubble, as do our specimens, though Corrêa (1963) does not mention a caudal cirrus. Our material consistently has a small caudal cirrus but it could easily be missed in preserved specimens. Pending anatomical studies, we assign our specimens to Dushia atra sensu Corrêa (1963). A potential taxonomic problem remains in that Girard (1893) describes his specimens as having been dredged from deep water off Cape Florida, which is at strong variance with the very narrowly constrained habitat of our specimens and those found on other Caribbean islands (JLN, pers obs).