Diopisthoporus lofolitis sp. nov. (Figs. 4–5)

Type Material: Holotype. AMNH PLATY 1645, set of 1.5­µm­thick serial frontal sections of male and female mature epoxy­embedded specimen stained with toluidine blue, collected October 2002. Paratype. AMNH PLATY 1646, set of 1.5­µm thick serial frontal sections of female mature, epoxy­embedded specimen stained with toluidine blue.

Type Locality. Oak Island, NC, from shallow subtidal medium grained sand inside Lockwoods Folly Inlet (33° 54' 53"N, 78° 14' 06"W).

Other Material Examined. Living specimens in squeeze preparations; one whole mount for fluorescence imaging of musculature.

Etymology. Species name is a combination of the words Lockwoods Folley Inlet, the type locality of this species.

Synonyms. Diopisthoporus cf. longitubus: Smith 1981, Smith & Tyler 1985.

Description. Male mature specimen ~300 long and ~80 µm wide; male immature specimens ~410 µm long (Figs. 4, 5). Body cylindrical. Anterior end rounded, posterior end blunt.

Epidermis without coloration by transmitted light. Epidermis completely ciliated. Rhabdoid and mucoid glands absent.

Body­wall musculature a simple gridwork of outer circular muscles and inner longitudinal muscles. A few longitudinal fibers angle diagonally at mid­body to cross over other straight diagonal muscles, then resume their longitudinal orientation (Fig. 5 C).

Frontal organ well developed; cell bodies of frontal glands positioned ~70 µm behind frontal pore (Figs. 4, 5 C).

Mouth opening terminal at posterior end of body, ventral side; opens to large ciliated pharynx lined with circular and longitudinal muscle fibers (Figs. 4, 5).

Ovary unpaired, dorsal. In male mature specimen ovary extends from statocyst posteriorly to anterior end of pharynx (Fig. 4).

Female gonopore, seminal bursa, and female accessories absent.

Testis unpaired, ventral, compact; separate from ovary. Testes extend from level of statocyst posteriorly to level of seminal vesicle. Sperm from testes extends from ventral to dorsal side to enter proximal end of seminal vesicle (Fig. 4).

Male gonopore terminal at posterior end of body; dorsal side. Gonopore leads to unciliated male antrum surrounded by mucoid gland cells that stain pink in toluidine blue. Proximal end of antrum opens to walled seminal vesicle (Figs. 4, 5 B).

Remarks. The genus Diopisthoporus contains four other known species, including the filiform D. gymnopharyngeus, which was also present in our collections from Lockwoods Folly Inlet. D. lofolitis is similar in general appearance to D. psammophilus Dörjes, 1968, and D. longitubus Westblad, 1940, in having a large, terminally opening, ciliated pharynx. However, a male copulatory organ has not been found in D. psammophilus, and although D. longitubus does have a terminally­opening male gonopore on its dorsal side, it is without mucoid gland cells surrounding the male antrum. Additionally, the testis of D. longitubus is positioned dorsally and the eggs ventrally—the reverse of what occurs in D. lofolitis .