Kuma albiventer ( Marcus, 1954 )

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 : 17-19

Kuma albiventer ( Marcus, 1954)

( Fig. 10 )

Haploposthia albiventer: Marcus 1954 (p 420); Mamkaev 1967 (p 40); Dörjes 1968 (p 97); Dörjes and Karling 1975 (p 180).

Kuma albiventer: Faubel 1976 (p 35); Hooge and Smith 2004 (p 16); Tekle 2004 (p 86).

Material. Topotype. MZUSP PL. 185, one set of 2-µm-thick serial sections of epoxyembedded specimen stained with toluidine blue; living specimens in squeeze preparations; one set of 2-µm-thick serial sections of epoxy-embedded specimen stained with toluidine blue.

Locality. Praia Barreiros, Ilhabela, São Paulo, Brazil, from subtidal coarse-grained sand with silt (23°45’52.2”S, 45°20’56.6”W).

Description. Mature living specimens ~470 long and ~100 µm wide ( Fig. 10 A). Body cylindrical. Anterior and posterior ends rounded; posterior more blunt. Body color reddish-brown by transmitted light ( Fig. 10 A). Epidermis completely ciliated. With scattered mucoid glands. Frontal organ well developed; frontal glands extend posteriorly to level of mouth ( Fig. 10 B). Mouth opening on ventral surface, anterior end of body.

Ovary unpaired, ventral. Testes paired, lateral to and separate from ovary. Female gonopore, seminal bursa, and female accessories all absent.

Male gonopore terminal at posterior end of body ( Fig. 10 B). Well-developed muscular and ciliated male antrum with large nuclei ( Figs. 10 B–D). Proximal opening of antrum surrounded by ring of two types of glands: large mucoid glands whose tips open into antrum ( Figs. 10 C, D) and smaller gland cells, with darkly staining granular contents ( Fig. 10 D). Seminal vesicle positioned at proximal end of antrum and surrounded by gland cells ( Fig. 10 D).

Remarks. Our specimens were collected near the type locality, in subtidal sand on the island of Ilhabela. Marcus’s (1954) species description described a dramatic color change for this species, whereby it was ivory white when first collected, but after exposure to light turned pink to purple to black within a few hours. We observed no such color change, but the dark reddish brown color of our specimens seems to fit with the intermediate color described by Marcus (1954).

Our observations of the male copulatory organ mostly match that of the original description. Marcus (1954) reported finding a small penis with a cuticular rosette, which he drew as a crown-shaped structure ( Marcus 1954, Fig. 5 ). We found the same structure in our histological sections, but determined that the structure was not a sclerotized penis, but rather a ring of gland cells, with granular contents, that are interspersed with the more prominent mucoid glands ( Fig. 10 D).

Figures

FIGURE 5. Philactinoposthia stylifera brasiliensis subsp. nov.; whole-mounts stained with Alexa- 488 - labeled phalloidin and viewed with confocal microscopy. A. Projection of ventral body-wall musculature. B. Lateral projection of copulatory organs. C. Dorsal projection of copulatory organs.

FIGURE 10. Kuma albiventer; photomicrographs. A. Dorsal view of squeezed living specimen. B. Oblique histological sections of whole specimen stained with toluidine blue. C, D. Histological sections through male copulatory organ. Arrows point to granular gland cells.