Proporus carolinensis, 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 : 19-21

Proporus carolinensis sp. nov. ( Figs. 13–15 )

Type Material: Syntypes. AMNH PLATY 1655 and AMNH PLATY 1656, two sets of 1.5­µm­thick serial sagittal sections of epoxy­embedded specimens stained with toluidine blue, collected October 2002. Paratype. AMNH PLATY 1657, 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; one whole mount for fluorescence imaging of musculature.

Etymology. Species name refers to North Carolina, the state from which the type material was collected.

Description. Mature specimens 650 to 800 µm long and ~150 µm wide ( Figs. 13 , 14 A, 15A). Specimens fixed for histological sectioning contracted considerably.

Body cylindrical. Anterior end rounded, posterior end tapers to blunt point.

Epidermis completely ciliated. Two types of rhabdoid glands present in epithelium; one large and cylindrically shaped, the other smaller with an irregular shape ( Fig. 13 , 14 B).

Body­wall musculature a simple gridwork of outer circular muscles and inner longitudinal muscles ( Fig. 15 C).

Frontal organ well developed; cell bodies of frontal glands positioned ~150 µm behind frontal pore in fixed specimens ( Fig. 13 ).

Mouth opening on ventral surface, anterior half of body; usually posterior to statocyst ( Fig 13 , 14 A, 15A), in one fixed specimen mouth opening extended anterior to level of statocyst ( Fig. 15 A). Mouth opens to ciliated pharynx with well­developed circular and longitudinal muscle fibers ( Fig. 13 , 15 A, C, D). Digestive central syncytium extends from frontal glands to posterior end of body.

Ovary unpaired, ventral; extends from level of pharynx posterior to middle of body. ( Fig. 13 ). Eggs not present in all examined specimens ( Fig. 15 A).

Testes paired, dorsal, follicular; separate from ovary. Testes extend posteriorly from position behind frontal glands to seminal vesicle ( Figs. 13 , 15 A, B).

Female gonopore absent. Male gonopore terminal at posterior end opens to ciliated, tubular male antrum ( Figs. 13 , 15 B). Wall of antrum with circular and longitudinal muscles, lined with nuclei, but without obvious glands. Proximal end of antrum opens to seminal vesicle with sperm arranged in parallel with longitudinal body axis ( Figs. 14 A, 15B).

Remarks. Proporus carolinensis appears to be most similar to P. lonchitus and P. minimus . These three species have pharynges that open posterior to the level of the statocyst; this is unlike the condition found in the other three known species of Proporus in which the mouth is located anterior to the statocyst. In addition, P. carolinensis and P. l o n ­ chitus are the only known species in the genus to have paired testes. In contrast, P. c a ro ­ linensis lacks the gut musculature found in P. minimus , and the glands surrounding the pharynx of P. lonchitus . Most importantly, P. carolinensis does not have glands opening into the male antrum, as is the case in all other known species in the genus.

Proporus carolinensis lacks accessory muscles that fan out from the mouth opening as found in another species of the Proporidae , Proporus bermudensis Hooge & Tyler, 2001 , and other pharynx­bearing turbellarians such as Macrostomum hystricinum (see Rieger et al. 1994).

Figures

FIGURE 13. Proporus carolinensis sp. nov.; sagittal reconstruction to show arrangement of organs. cs, digestive central syncytium; e, egg; fg, frontal gland; m, mouth; ma, male antrum; ph, pharynx; rh, rhabdoid gland; st, statocyst; sv, seminal vesicle; t, testes.

FIGURE 14. Proporus carolinensis sp. nov.; photomicrographs of living specimen. A. Ventral view of of whole animal. B. Rhabdoid glands.

FIGURE 15. Proporus carolinensis sp. nov.; photomicrographs. A, B. Sagittal histological sections. C, D. whole­mount stained with Alexa­ 488 ­ labeled phalloidin and viewed with confocal microscopy. C. Focus on ventro­lateral body­wall musculature and mouth. D. Focus on musculature of pharynx. ma, male antrum; sv, seminal vesicle; t, testes.