Notospermus Huschke, 1830

Gibson, Ray & Sundberg, Per, 2002, Some heteronemerteans (Nemertea) from the Solomon Islands, Journal of Natural History 36 (15), pp. 1785-1804 : 1787-1788

Genus Notospermus Huschke, 1830

The genus Notospermus was originally established by Huschke (1830) for a single species, N. drepanensis Huschke, 1830 . Ehrenberg (1831) unaccountably changed the generic name of this taxon to Notogymnus, Örsted (1844) later transferring the species to the genus Nemertes . Oudemans (1885) subsequently listed Notospermus drepanensis as a junior synonym of Cerebratulus geniculatus (Delle Chiaje, 1828) , Bürger (1892) placing C. geniculatus in the genus Lineus . Vaillant (1890) and Bürger (1895), amongst others, listed Notospermus as a junior synonym of the genus Lineus Sowerby, 1806 , and for many years Lineus geniculatus was regarded as a valid species. Riser (1991) re-examined several specimens of L. geniculatus from many parts of the world, as well as examples of L. mitellatus Takakura, 1898 , and Micrura tridacnae Gibson, 1981 , and concluded that all were representative of the same species, L. geniculatus . Riser (1991: 427) noted that ‘According to current taxonomic analyses of the Heteronemertinea, [this] species belongs in the genus Pseudolineus Friedrich, 1960 , which is a junior synonym of Notospermus Huschke, 1830 ’, and accordingly reinstated the generic name Notospermus , with N. geniculatus (Delle Chiaje, 1828) as the type species. Riser also discussed the systematics of Lineus tricuspidatus (Quoy and Gaimard, 1833) and transferred this species to the genus Notospermus .

Diagnosis

Riser’s (1991) studies on Notospermus geniculatus , the type species for the genus, supplemented by the description of Micrura tridacnae (which Riser synonymized with N. geniculatus ) given by Gibson (1981), allow the genus Notospermus to be diagnosed as: Heteronemertea with a single pair of lateral horizontal cephalic furrows; proboscis unbranched, initially with outer longitudinal, middle circular and inner longitudinal muscle layers and two muscle crosses, but outer longitudinal layer disappearing posteriorly; rhynchocoel circular musculature initially interwoven with adjacent body wall longitudinal muscles; all musculature below rhynchocoelic villus interwoven; dorsal bre core of cerebral ganglia forked only at rear into upper and lower branches; nervous system with neither neurochords nor neurochord cells; cerebral ganglia with outer neurilemma; foregut with longitudinal somatic muscles, without subepithelial gland cell zone; buccal wall surrounded by subepithelial glands; dermis with connective tissue layer separating glandular region from body wall outer longitudinal musculature; caudal cirrus absent; apical sensory organs absent; cephalic glands absent; eyes present; sexes separate.