Parapharyngiella involucrum, Willems & Artois & Vermin & Backeljau & Schockaert, 2005
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publication ID |
https://doi.org/ 10.1080/00222930400014239 |
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persistent identifier |
https://treatment.plazi.org/id/03FA2A32-481C-FFB0-2A01-E627FC78FABA |
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treatment provided by |
Felipe |
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scientific name |
Parapharyngiella involucrum |
| status |
gen. nov. |
Parapharyngiella involucrum View in CoL gen. nov. sp. nov.
parapharyngiella-involucrum sp. nov.
( Figure 3 View Figure 3 )
Diagnosis
Parapharyngiella gen. nov. Trigonostominae with the pharynx situated in the first body half. Paired testes in front of the pharynx. Paired ovovitellaria with the ovaries and atrial organs situated just caudally to the pharynx. Prostate stylet a curved tube, distally surrounded by the mantle. Additional vesicle (with sperm) at the proximal part of the female (efferent) duct. Afferent system consisting of curling duct and large, thin-walled bursa (with sclerotized bursal stalk). Mouthpiece of bursa consisting of a club-shaped part surrounded by a barrel-shaped part. Type species: Parapharyngiella involucrum .
Parapharyngiella involucrum sp. nov. Provisionally with the same diagnosis as the genus. Stylet 48 Mm long.
Locality
Zanzibar, Mahurubi Palace Ruins : beach with detritus-rich sand, churned up by crabs, at low tide (5 August 1995) (type locality) .
Material
Four specimens studied alive and whole mounted, one of them designated holotype ( LUC no. 280), the others paratypes ( LUC nos 281–283). One serially sectioned specimen (paratype; LUC no. 284) .
Etymology
The genus name/praenomen refers to the position of the genital system, just behind the pharynx; para (Greek): close to; gender: feminine. The species epithet refers to the partially sclerotized wall of the bursal stalk, giving it the appearance of a kind of envelope; involucrum (Latin) : envelope.
Description
The animals are ¡ 1 mm long (measured on whole mounts), with two eyes. The cellular epidermis is about 3 Mm thick with cilia of 3–4 Mm long. Numerous minute rhabdites occur throughout the epidermis. Close behind the eyes, some basophilic glands ( Figure 3A View Figure 3 : rg) are present and produce rod-shaped adenal rhabdites, which are ¡6 Mm long. The gland necks are organized in two long tracts, fusing at the level of the eyes and opening terminally at the rostral body end.
The pharynx is situated at about 30%. It has 24 internal longitudinal muscles. The more detailed structure could not be determined, but does not seem to differ from that of most other trigonostomids.
The paired testes are rather small and globular and lie just in front of the pharynx ( Figure 3A View Figure 3 ). The dorsally situated, paired ovovitellaria extend from the level of the testes to the caudal body-end, with the ovaries just behind the pharynx. Also all other reproductive structures are located immediately behind the pharynx (see Figure 3A, B View Figure 3 ). The common genital pore is situated at ¡40%. The common genital atrium is surrounded by inner circular and outer longitudinal muscles, and lined with a nucleated and frayed epithelium (pseudociliation).
The paired seminal vesicles are lined with a low, nucleated epithelium and surrounded by circular muscles. Just before entering the prostate vesicle ( Figure 3B View Figure 3 : vg), both seminal vesicles join to form the seminal duct ( Figure 3D View Figure 3 : ds). It runs axially through this prostate vesicle, but is only clearly visible in the proximal part. Both prostate vesicle and male atrium are surrounded by circular muscles. There are two types of prostate glands: eosinophilic glands situated dorsally ( Figure 3D View Figure 3 : gg2) and basophilic ones ventrally ( Figure 3D View Figure 3 : gg1). Extracapsular parts of the glands were seen only on live material ( Figure 3B View Figure 3 : gg). The complex stylet ( Figure 3C View Figure 3 ) is 44–55 Mm long (mean548 Mm; n 54) and consists of a very narrow, thick-walled tube, giving it the shape of a question mark when viewed laterally. The distal part (about 60%) is surrounded by a large plate (‘‘mantle’’ of Ax 1971). Distally, this plate ( Figure 3C View Figure 3 : mt) ends in a broad hook.
The ovoid ovaries are situated dorsal to the prostate vesicle. The short oviducts are lined with a low, nucleated epithelium and join to form the female duct (5efferent duct; Figure 3D View Figure 3 : fd), which enters the atrium dorsally. The female duct is surrounded by a strong sphincter at its proximal end, where a large bundle of eosinophilic glands ( Figure 3D View Figure 3 : fg) surrounds and enters the female duct. Proximally the female duct ends in a small, globular sperm-containing vesicle ( Figure 3D View Figure 3 : av), the entrance of which is guarded by a sphincter. The afferent system consists of a large bursa ( Figure 3D View Figure 3 : bu) and a sclerotized duct, which connects the bursa with the sperm-containing vesicle on the female duct. Where it leaves the bursa, this duct widens and contains a large mouthpiece ( Figure 3D View Figure 3 : mp; not visible on whole mounts), which is a complex sclerotized structure, consisting of an inner club-like part, surrounded by a barrel-shaped part. The latter part is probably the thickened wall of the surrounding duct. The bursa has a thin and extremely folded wall, is filled with sperm and eosinophilic secretion, and is connected to the genital atrium by a narrow duct (bursal stalk; Figure 3D View Figure 3 : bs), which is lined with a thick sclerotized basement membrane. In about its middle, the bursal stalk widens and the basement membrane is clearly thicker on one side, giving it the appearance of a kind of envelope. A uterus is lacking.
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