Pseudohaplogonaria cerasina, 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 : 16-18

Pseudohaplogonaria cerasina sp. nov. ( Figs. 11–12 )

Type Material: Syntypes. AMNH PLATY 1653 and AMNH PLATY 1654, two sets of 1.5­µm­thick serial oblique longitudinal sections of epoxy­embedded specimens stained with toluidine blue, collected October 2002.

Type Locality. Oak Island, NC, from shallow subtidal coarse to 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 from the Latin cerasinus, cherry­colored, and refers to the bright red rhabdoids in this species.

Description. Mature specimens approximately 650 µm long and 100 µm wide ( Figs. 11 , 12 A). Body cylindrical. Anterior and posterior ends rounded. Uncolored body by transmittted light.

Epidermis completely ciliated. Many bright red as well as uncolored rhabdoids present in body wall; mostly concentrated on ventral side ( Fig. 11 , 12 C).

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 but then bend medially to cross diagonally over the body (longitudinal­cross­over fibers) present in both dorsal and ventral body wall; anterior end with ventral diagonal muscles positioned between outer circular and inner longitudinal muscles (data not shown).

Frontal organ well developed; cell bodies of frontal glands positioned ~250 µm behind frontal pore ( Fig. 11 A, B).

Mouth opening on ventral surface, middle of body. Digestive central syncytium extends nearly entire length of body.

Ovary unpaired, ventral; extends from mouth posteriorly to bursal nozzle ( Fig. 11 B).

Testes paired, dorsal, compact; separate from ovary. Testes extend anteriorly to position ~220 µm behind anterior tip and posteriorly to male copulatory organ.

Female gonopore and vagina absent. Seminal bursa leads to robust bursal nozzle ~30 µm in length ( Figs. 11 B, C, 12B, D).

Male gonopore ventral, at posterior end; leads to non­muscular penis composed of spongy tissue with large nuclei ( Figs. 11 C, 12B, D). Large masses of sperm present at lateral sides of penis; true seminal vesicle absent.

Remarks. Among species in the family Haploposthiidae , members of the genus Pseudohaplogonaria are united in having a seminal bursa with a sclerotized bursal nozzle, and a weakly developed or absent seminal vesicle. P. cerasina is most similar to P. minima (Ehlers & Dörjes, 1979) , which also has paired testes, an unpaired ovary, conspicuous rhabdoids, and a bursal nozzle. P. minima , however, is more stout­bodied than P. cerasina , has a smaller male copulatory organ, and a common gonopore that opens to the seminal bursa via a short vagina.

Figures

FIGURE 11. Pseudohaplogonaria cerasina sp. nov.; reconstructions to show arrangement of organs. A. Dorsal reconstruction of whole specimen. B. Sagittal reconstruction of whole organism. C. Sagittal reconstruction of reproductive structures. bn, bursal nozzle; cop, male copulatory apparatus; cs, digestive central syncytium; cv, chordoid vacuole; e, egg; fg, frontal gland; m, mouth; mgp, male gonopore; p, penis; rh, rhabdoid gland; sb, seminal bursa; sp, sperm; st, statocyst; t, testes.

FIGURE 12. Pseudohaplogonaria cerasina sp. nov.; photomicrographs. A. Dorsal view of living specimen. B. Dorsal view of posterior of living specimen. C. Rhabdoid glands. D. Sagittal view of reproductive organs in living specimen. bn, bursal nozzle; cv, chordoid vacuole; p, penis; sb, seminal bursa; sp, sperm.