Hooge & Tyler 2004 (citation) - 'Mature specimens ~1100 µm long and ~200 µm wide (Figs. 1, 2A). Body somewhat flattened. Anterior and posterior ends rounded. Epidermis completely ciliated. By transmitted light epidermis reddish-brown in color due to pigment granules. Reddish-orange rod-shaped gland secretions present in long tracts underneath ventral epidermis (Fig. 2C). Scattered mucoid glands present in epithelium (Fig. 2B, 3A). Body-wall 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 (longitudinal-cross-over fibers present in dorsal body wall; longitudinal muscles in the anterior half of body that wrap around the posterior rim of mouth (U-shaped 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. 1A-C). Mouth opening on ventral surface, middle of body. Several examined specimens had conspicuous vacuole in immediate vicinity of mouth (Fig. 1C). Ovaries paired, ventral. Egg strands paired or unpaired; extend from position anterior of mouth posteriorly to bursal nozzle (Figs.1, 3A). 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, 2D,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. 1C, 2D, 3B). Several actin-rich stimulatory organs known as adenodactyls also present (Figs. 1, 2D, 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, 3B, C). Additional adenodactyls, flanking lateral sides of male copulatory organ present in some specimens (data not shown).' 'This species is placed in the family Anaperidae due to the presence of needle-like 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.'[From Hooge MD, Smith JPS (2004)]
Notes from synonyms
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