Itaipusa biglandula, Reygel, Patrick C., Willems, Wim R. & Artois, Tom J., 2011

Reygel, Patrick C., Willems, Wim R. & Artois, Tom J., 2011, Koinocystididae and Gnathorhynchidae (Platyhelminthes: Rhabdocoela: Kalyptorhynchia) from the Galapagos, with the description of three new species, Zootaxa 3096, pp. 27-40 : 30-31

Itaipusa biglandula n. sp.

( Fig. 2 )

Locality. Santa Cruz Island, Bahia Academy, Station IX 5 g, upper layer of coarse-grained sand (type locality).

Material. Several specimens studied alive. A total of 42 serially-sectioned animals, one of which is designated holotype ( ZMUG 23231), 13 others designated paratypes ( ZMUG 23232-23244). Voucher specimens deposited as ZMUG 23252-23279.

Etymology. Species name refers to the presence of two symmetrical atrial glands. Glandula (Lat.) : gland.

Diagnosis. Species of Itaipusa Marcus, 1949 , with two atrial glands symmetrically located beside the female duct; male system with a short, unarmed penis papilla; large bursa with resorptive part and muscular bursal stalk opening into female duct.

Description. Live animals ± 1.3 mm long, caudally rounded, with two eyes. The syncytial epidermis is ± 6 µm thick and shows a prominent basement membrane. It contains numerous apically-elongated, oviform, 2−4 µm long rhabdites, which are absent in the head region, from the anterior tip to half the proboscis length. The animal is ciliated over the entire body (cilia ± 6 µm long) with sensory bristles (± 25 µm long) surrounding the proboscis opening.

The proboscis measures almost 1/5 of the body length and shows the characteristic features of a typical koinocystidid proboscis (see Brunet 1972; Karling 1980). It has a very strong Itaipusa - type proboscis juncture sphincter (see Karling 1980: p. 260).

The pharynx is situated at about 40%, and does not show any peculiarities in comparison with other species of Itaipusa or Koinocystididae in general (see Meixner (1925) and Karling (1954, 1980) for a detailed account). The oesophageal glands, clearly visible in sectioned material, are not distinguishable on live animals. A pharynx mouth sphincter could not be observed on sectioned specimens.

Male and female gonads are paired. The oval testes lie dorso-laterally, caudally from the pharynx, extending to the distal part of the ovaries, which are situated at ± 75%. The vitellaria extend from the mouth to the ovaries, the anterior part being situated dorso-laterally, whereas the posterior part lies more central and ventrally to the testes. The common genital pore, situated at ± 90%, opens into the common genital atrium, which is lined with a high, nucleated epithelium and is surrounded by longitudinal muscles. Anteriorly it receives the uterus, and the male duct more dorsally. The female system opens into the genital atrium from the dorso-caudal side.

The elongated, paired seminal vesicles are lined with a low, nucleated epithelium and surrounded by longitudinal muscles. Both vesicles fuse just before entering the prostate vesicle, forming the ejaculatory duct. This duct runs centrally through the prostate vesicle and is surrounded by eight to ten filiform prostate gland necks, called prostate ducts by Karling (1980). The prostate glands proper are very large, surrounding the seminal vesicles and containing one type of basophilic, coarse-grained secretion. The almost globular prostate vesicle bulges into the male genital atrium in a short, muscular penis papilla. The exact course of the ejaculatory duct could not be revealed, except for its distal part that opens into the penis papilla. This part of the ejaculatory duct is surrounded by circular muscles. The male atrium is lined with a low, anucleated epithelium and does not seem to be surrounded by a muscle layer.

The ovoid ovaries have short oviducts, which join to form the female duct and are lined with a low, anucleated epithelium. On this bifurcation, a short vitelloduct enters the female duct. This female duct is lined with a low, nucleated epithelium and surrounded by weak, circular muscle fibres, forming a strong sphincter distally. Although no sperm could be observed in this duct, it probably acts as a seminal receptacle, indicated by the fact that it is swollen in all specimens. Instead of opening into the common genital atrium, it is connected to a very muscular bursal stalk, which enters the atrium dorso-caudally, together with two symmetrically-placed, glandular complexes with fine-grained eosinophilic secretion ( Fig. 2 B: gl). Over its whole length this stalk is surrounded by circular muscles, which are extremely thick proximally, close to the bursal organ proper, forming two very large sphincters. The bursa acts as a sperm-resorbing organ (resorptive vesicle of Karling 1980). The bursa has a nucleated epithelium, which merges with the sperm-resorbing mass more proximally.

The uterus is lined with a high, nucleated epithelium and surrounded by spirally-running muscle fibres. It opens into the common genital atrium close to the genital pore and is provided with two types of glands. The first type contains a fine-grained eosinophilic secretion and is situated near the proximal end, although the exact location of the opening into the uterus is unclear. More distally a coarse-grained basophilic gland type is present. These glands open into the uterus lumen half way along the organ.

Discussion. See the general discussion on Itaipusa following the remarks on I. variodentata ( Karling et al., 1972) Karling, 1978 .

Figures

FIGURE 2. Itaipusa biglandula n. sp. A, general organisation (from a live specimen). B, reconstruction of the atrial organs from the left hand side (from the holotype).