Anaperus singularis, Hooge, Matthew D., Smith, Julian P. S. & Iii, 2004

Hooge, Matthew D., Smith, Julian P. S. & Iii, 2004, New acoels (Acoela, Acoelomorpha) from North Carolina, Zootaxa 442, pp. 1-24 : 2-6

publication ID	https://doi.org/ 10.5281/zenodo.157611
DOI	https://doi.org/10.5281/zenodo.6273402
persistent identifier	https://treatment.plazi.org/id/03CE390F-561C-FF97-FEC3-CC8333903690
treatment provided by	Plazi
scientific name	Anaperus singularis
status	sp. nov.

Treatment

Anaperus singularis sp. nov. ( Figs. 1–3)

Type Material. Syntypes. AMNH PLATY 1642 and AMNH PLATY 1643, two sets of 1.5µmthick serial sagittal sections of epoxyembedded specimens stained with toluidine blue, collected October 2002. Paratype. AMNH PLATY 1644, epoxyembedded whole mount.

Type Locality. Oak Island, NC, from shallow subtidal medium grained sand at the Lockwoods Folly Inlet (33° 55' 03"N, 78° 13' 58"W).

Other Material Examined. Living specimens in squeeze preparations; set of 1.5 µmthick serial sagittal sections of epoxyembeded specimen; one whole mount for fluorescence imaging of musculature.

Etymology. Species name comes from the Latin singularis , alone, and refers to the single bursal nozzle in this species.

Synonyms. Anaperus sp.: Smith 1981, Smith & Tyler 1985.

Description. Mature specimens ~1100 µm long and ~200 µm wide ( Figs. 1, 2 View FIGURE 2 A). Body somewhat flattened. Anterior and posterior ends rounded.

Epidermis completely ciliated. By transmitted light epidermis reddishbrown in color due to pigment granules. Reddishorange rodshaped gland secretions present in long tracts underneath ventral epidermis ( Fig. 2 View FIGURE 2 C). Scattered mucoid glands present in epithelium ( Fig. 2 View FIGURE 2 B, 3A).

Bodywall musculature with circular muscles that encircle the body along entire length of animal; straight longitudinal muscles present between frontal organ and anterior edge of mouth; longitudinal muscles with a longitudinal orientation anteriorly that bend medially to cross diagonally over the body (longitudinalcrossover fibers present in dorsal body wall; longitudinal muscles in the anterior half of body that wrap around the posterior rim of mouth (Ushaped muscles) present in ventral body wall (data not shown).

Frontal organ well developed; cell bodies of frontal glands positioned ~200 µm behind frontal pore in fixed specimens ( Fig. 1 A–C).

Mouth opening on ventral surface, middle of body. Several examined specimens had conspicuous vacuole in immediate vicinity of mouth ( Fig. 1 C).

Ovaries paired, ventral. Egg strands paired or unpaired; extend from position anterior of mouth posteriorly to bursal nozzle ( Figs.1, 3 View FIGURE 3 A).

Testes paired, lateral to eggs, follicular; separate from ovary. Testes extend from position near level of mouth posteriorly to level of bursal nozzle ( Fig. 1).

Female gonopore absent. Unwalled seminal bursa leads to curved bursal nozzle ~40 µm long ( Figs. 1, 2 View FIGURE 2 D, 3A).

Male gonopore ventral at posterior end of body. Pore surrounded by mucoid glands that stain pink in toluidine blue. Male copulatory organ composed of a loose arrangement of muscles surrounding a small muscular penis. Copulatory organ surrounded by strands of darkly staining glandular secretions ( Figs. 1 C, 2D, 3B). Several actinrich stimulatory organs known as adenodactyls also present ( Figs. 1, 2 View FIGURE 2 D, 3B, C). Two adenodactyls present anterior to copulatory organ; extend through the ventral epidermis anterior to the male gonopore. Large adenodactyl positioned immediately behind copulatory organ; opens into male antrum ( Figs. 1, 3 View FIGURE 3 B, C). Additional adenodactyls, flanking lateral sides of male copulatory organ present in some specimens (data not shown).

Remarks. This species is placed in the family Anaperidae due to the presence of needlelike adenodactyls. The presence of a bursal nozzle along with an unwalled seminal bursa is characteristic of members of the genus Anaperus . Like other anaperids, the adenodactyls of Anaperus singularis are closely associated with gland cells, and our phalloidin stained specimen reveals that the adenodactyls in this species also contain a considerable amount of actin. Besides having a unique arrangement of adenodactyls, A. singularis is distinguished from all other known species in the genus Anaperus in having only a single bursal nozzle; other known species have two or more nozzles.