Nemertopsis bivittata (Delle Chiaje, 1841)

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 : 94-95

Taxon classification Animalia Heteronemertea Monostilifera

Nemertopsis bivittata (Delle Chiaje, 1841) Fig. 4 A–C

Description.

One specimen up to about 20 mm long; 1 mm wide; rounded at both ends. Yellow milky base color, dorsally with 2 brown to reddish longitudinal lines joined at anterior and posterior ends. Cerebral organ furrows precerebral, difficult to see. Head almost undifferentiated from body. Cephalic grooves not visible. Two pre-cerebral eyes on each lateral margin of head. Rhynchopore subterminal; proboscis small, slender provided with papillae; short central stylet (length: 11 µm), supported on a massive base (27 × 7 µm). Two pouches containing three accessory stylet each.

Distribution.

USA East Coast - Florida ( Thollesson and Norenburg 2003), South Carolina ( Caplins et al. 2012); Atlantic Galician Island ( Junoy and Herrera-Bachiller 2010); European waters, Portuguese and Spanish Exclusive Economic Zone, Red Sea ( Gibson 2014b); Santa Marta, Colombia.

Comment.

Caplins et al. (2012) found support suggesting that the two color morphs of Nemertopsis bivittata commonly found sympatrically - one with dorsal stripes that meet anteriorly and the other with lines that do not meet - are genetically isolated. Support includes statistical difference in size of stylets and in DNA sequence differences for mitochondrial cytochrome-oxidase-1 gene - minimum and an a maximum pair-wise difference of 13.6% and 19.9% - ( Caplins et al. 2012). Though awaiting explicit molecular data, Norenburg (2013) commented that Nemertopsis bivittata and Nemertopsis gracilis Coe, 1904, probably are synonyms and, therefore, following Sun and Dong (1998), the morph with lines meeting would be Nemertopsis bullocki Coe, 1940 and the one with stripes not meeting would be, by priority, Nemertopsis bivittata (Delle Chiaje, 1841). For now, we do not formally distinguish the two here and assign our specimen at Nemertopsis bivittata .