Haplogonaria sophiae, Hooge, Matthew D. & Rocha, Carlos E. F., 2006

Hooge, Matthew D. & Rocha, Carlos E. F., 2006, Acoela (Acoelomorpha) from the northern beaches of the state of São Paulo, Brazil, and a systematic revision of the family Otocelididae, Zootaxa 1335, pp. 1-50 : 15-16

Haplogonaria sophiae sp. nov.

( Figs. 8–9 )

Type material. Holotype. MZUSP PL. 183, one set of 2-µm-thick serial sagittal sections of epoxy-embedded specimen stained with toluidine blue. Paratype. MZUSP PL. 184, one set of 2-µm-thick serial sagittal sections of epoxy-embedded specimens stained with toluidine blue.

Type locality. Itaçucê Island, São Sebastião Channel, São Paulo, Brazil, from coarse shelly sand with silt taken from 5 m water depth (23°49’S, 45°20’W).

Other material examined. Living specimens in squeeze preparations; whole mount for fluorescence imaging of musculature.

Etymology. Species name in honor of Ms. Sophie Suhr of Portland, Oregon, USA.

Description. Living specimens 450–650 µm long and 150 µm wide ( Fig. 8 A). Anterior and posterior ends rounded; posterior end more narrow. Body colorless by transmitted light. Digestive syncytium often with red and green contents, including conspicuous pennate diatoms ( Figs. 8 B, 9A). Epidermis completely ciliated. Many large, scattered rhabdoid glands present ( Fig. 8 C, 9A). Frontal organ well developed; cell bodies of frontal glands positioned ~100 µm behind frontal pore ( Fig. 9 A). Mouth opening on ventral surface, middle of body. Digestive central syncytium extends from posterior end of frontal glands to level of seminal vesicle.

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-cross-over muscles (fibers with a longitudinal orientation anteriorly, but bend medially to cross diagonally) present in both dorsal and ventral body wall; longitudinal muscles in anterior half of body that wrap around posterior rim of mouth (U-shaped muscles) present in ventral body wall; ventral diagonal muscles in anterior half of body absent ( Fig. 9 B).

Ovaries paired, ventral; extend from level of mouth posteriorly to seminal bursa ( Figs. 8 A, B, 9A). Testes paired, lateral to ovaries; extend from frontal glands posteriorly to male copulatory organ.

Female gonopore absent. Thin-walled seminal bursa positioned ventrally, immediately anterior to seminal vesicle and posterior to developing oocytes ( Fig. 9 A).

Male gonopore ventral at posterior end of body; opens to ciliated male antrum. Antrum opens to muscular seminal vesicle filled with sperm. Penis absent. ( Figs. 8 B, 9A, C).

Remarks. In most of the 15 described species of Haplogonaria , the seminal bursa and seminal vesicle connect to a common gonopore. Although we could not discern a connection between the gonopore and seminal bursa in our species, the close proximity of these structures raises the possibility that a facultative connection exists. H. sophiae is similar to H. idia in having paired ovaries; all other known species in the genus have an unpaired ovary. Hooge and Eppinger (2005) pointed out that the genus Haplogonaria contains some species, such as H. sophiae , with a muscular seminal vesicle, and others with a non-muscular or weakly muscular seminal vesicle. It is probable that this character is of systematic importance and is indicative of separate phylogenetic lineages within the genus.

Figures

FIGURE 8. Haplogonaria sophiae sp. nov.; photomicrographs of a living specimen. A. Dorsal view of lightly squeezed specimen. B. Dorsal view of posterior end of specimen. C. Portion of anterior end, showing rhabdoid glands.

FIGURE 9. Haplogonaria sophiae sp. nov.; A. Sagittal histological section of holotype. B, C. Projections of whole-mount stained with Alexa- 488 - labeled phalloidin and viewed with confocal microscopy. B. Ventral view of body-wall musculature. C. Dorsal projection through lumen of seminal vesicle.