Sanjuannemertes, Iwata, 2006

Iwata, Fumio, 2006, On four monostiliferous hoplonemerteans, including three new genera and species from Washington state and British Columbia, Journal of Natural History 40 (15 - 16), pp. 873-913 : 904

Genus Sanjuannemertes gen. nov.

Type species

Sanjuannemertes aeilloaesi gen., sp. nov.

Etymology

The genus name refers to the area in which the type specimen was collected. The species name is dedicated to Professor A. O. Dennis Willows for his support of my work on nemertean taxonomy.

Diagnosis

Monostiliferous marine hoplonemerteans with two oblique cephalic grooves and four large ocelli arranged in form of a trapezoid; proboscis pore and mouth opening ventrally into common atrium on anterior tip of head; body wall musculature with a lattice-type diagonal layer, longitudinal muscles not divided anteriorly; rhynchocoel nearly equal to body length, with wall containing two distinct muscle layers; proboscis long and stout, with distinct outer circular and inner longitudinal muscle layer; proboscis armature consisting of single central stylet and two accessory stylet pouches; pre-cerebral septum and proboscis insertion ventrally incomplete; cephalic retractor muscles absent; longitudinal musculature in anterior region of head well-developed; foregut divisible into stomach, pylorus, intestinal caecum with lateral diverticula, main intestinal canal without deep lateral diverticula, and hind gut; cerebral sensory organ large and extending to lateral sides of brain lobes; cerebral ganglia small, with neither neurochord cells nor inner neurilemma; dorsal ganglia not separated from ventral ganglia; dorsal ganglia without bifurcated lobes; lateral nerve cords without accessory nerves or myofibrillae, and with peripheral nerves; blood vascular system with simple vascular loop in head, not entering brain ring; dorsal vessel without single vascular plug and three post-cerebral vessels not linked by pseudometameric transverse connectives; dorso-ventral muscle fibres and parenchyma absent; frontal organ composed of pore and small number of frontal glands; excretory system confined to foregut region of body, lacking efferent ducts; sexes probably separate.

Type species

Sanjuannemertes aeilloaesi

Body color without pattern; two cephalic grooves present, with opening of cerebral organ at lateral side of anterior groove; epidermis thick, with columnar glands confined to upper portion; proboscis with 10 nerves; proboscis anterior chamber with two muscle layers (outer circular and inner longitudinal); brain with a thin neurilemma; mid-dorsal nerve lacking; dorsal ganglia not separated from ventral ganglia, without bifurcated fibre core; paired foregut nerves originating from ventral ganglia; cerebral sensory organ with thin neurilemma; cerebral organ canal, beginning at mid-lateral side of anterior cephalic groove with a widened sac; excretory tubules lacking.