Punnettia cf. natans (Kirsteuer, 1973)

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 : 99-100

Taxon classification Animalia Hoplonemertea Polystilifera

Punnettia cf. natans (Kirsteuer, 1973) Fig. 5 L–M

Description.

One specimen about 17 mm long, <1 mm wide; dorsoventrally flattened, tapered at both ends. Gray to brown color, darker on head and along mid-dorsal line of body; ventral surface milky gray. Head narrow with respect to body. Cerebral organ furrows wide, postcerebral, subdivided by about 5 longitudinal epithelial ridges (secondary furrows) orthoganol to furrow axis. Numerous large ocelli, precerebral, arranged in four irregular longitudinal rows, outer rows possibly divided into anterior and posterior clusters. Armature normally several stylets supported on a single basis, but not documented by us. Individuals capable of swimming by undulatory movements, leaving mucus behind it.

Distribution.

Bahía Mochima (Venezuela) ( Kirsteuer 1973); Santa Marta, Colombia.

Comment.

Two named polystiliferan species are known from the region. Polyschista curacaoensis Stiasny-Wijnhoff, 1925 is known only from three pieces - two heads and a tail - already preserved and strongly contracted when first examined by Stiasny-Wijnhoff; therefore, of dubious value for anatomical study. The heads are described as having a "a well defined brown longitudinal marking on their back" while "the margins are a milky, transparent white and two to three times as broad as the thick [brown] middle part". The tail is described as being transparent and white. This does not fit well the present species. Curranemertes natans Kirsteuer, 1973 is known only from Venezuela and described as "orange to brownish" dorsally, with the thicker median region of the head being a "darker brownish shade". Though Kirsteuer (1973) concludes that the two species differ in internal anatomy, he cites only character states that he presumes “probably” differ in Polyschista . We are not sanguine that our specimen is either species, though it resembles specimens previously collected by JLN off Belize and Bocas del Toro, Panama and identified as Curranemertes cf. natans.

Härlin (1998), with support from a morphological phylogenetic analysis re-assigned Curranemertes natans to the phylo-clade Punnettia . Härlin and Härlin (2000) found Punnettia to be paraphyletic but without placing the type species, Punnettia hubrechti . They concluded by discarding Punnettia , in a Phylocode act, with the argument that it is "a messy name" and assigning its species to two phylo-clades but without placing Punnettia hubrechti . Thus, with respect to a Linnean classification, we cannot know which Punnettia species would remain so, because they form a clade with Punnettia hubrechti . Hence, it seems more appropriate at this time to retain Curranemertes natans , pending resolution of Punnettia phylogeny.