Orostylis dohae, sp. nov.
Creators: name: GOBERT, STEFAN
name: ARMONIES, WERNER
name: DIEZ, YANDER L.
name: JOUK, PHILIPPE
name: MONNENS, MARLIES
name: REVIS, NATHALIE
name: REYGEL, PATRICK
name: SMITH, JULIAN III
name: STEENKISTE, NIELS VAN
name: ARTOIS, TOM
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Platyhelminthes
Rhabdocoela
Solenopharyngidae
Orostylis
Orostylis dohae

description: Orostylis dohae sp. nov. Gobert, Van Steenkiste & Artois
(Figs. 2, 3A, 4D)
Neodalyellida n. gen. n. sp. 2 in Van Steenkiste et al. (2013)
Neodalyellida sp. 2 in Stephenson et al. (2019)
Localities. Doha, Qatar (25°19’04”N; 51°32’18”E) Sand at about the high-water mark (Mar. 19, 2008): Type locality.
Material. Observations on live specimens. One whole mount designated holotype (FMNH KV.690), and two serially sectioned specimens (HU XIV.3.04– XIV.3.05).
Etymology. Species named after the capital of Qatar, where the species was discovered.
Description. Animals are about 0.6 mm long (measured on whole mount), with two dark brown, kidney-shaped eyes (Figs. 2A, 4D: e). The epidermis is syncytial, strongly ciliated, and 2–5 μm thick. The cilia measure 2–3 µm. Nuclei in the epidermis are scarce. A thin basal membrane underlies the epidermis, followed by a circular and a longitudinal muscle layer, respectively. Several basophilic, coarse-grained glands are situated in the anterior end of the body, in the area surrounding the mouth. The caudal end of the body contains eosinophilic cement glands.
The mouth is located near the anterior end of the body (Fig. 2A: m) and surrounded by a sphincter. A long, thin-walled oral tube connects the mouth opening to the pharynx. The pharynx (Figs. 2, 4D: ph) is located in the anterior body half and is between 1/4 and 1/5 of the body length long. The pharynx is cylindrical in shape, with a conspicuous musculature, including radial, circular, and longitudinal muscles. This is typical for the pharynx doliiformis in neodalyellids, but the radial muscles are very wide and stacked closely together with little or seemingly no space between them. The anterior end of the pharynx bears a “collar” (Fig. 2A: phc) separated by a constriction from the rest of the pharynx. This collar is provided with three pairs of tentacles projecting anteriorly (Figs. 2A, 4D: pht). The intestine (Fig. 2B: i) lies caudally from the ovary (Fig. 2: ov). In live specimens, diatom frustules were observed inside the intestinal tract.
The large, paired testes are situated just anterior to the midbody (Figs. 2, 4D: t), behind the pharynx, on either side of the body. In live specimens, two distinct testes were clearly observed. However, in the serial sections, the separation between both testes was less obvious, creating the impression of a single, large testis. The two testes lie against one another in such a way that the spermatogenic distal ends of the testes point laterally.A pair of vasa deferentia extend anteriorly and connect the testes to the seminal vesicle (Figs. 2, 4D: sv) in the proximal half of the male copulatory organ. The copulatory organ is situated in the anterior part of the body, alongside the pharynx. It consists of the round to ovoid seminal vesicle (Figs. 2, 4D: sv), followed distally by a small, globular prostate vesicle (Fig. 2B: pv) filled with eosinophilic gland secretions. The seminal and prostate vesicle are lined with a syncytial, nucleated epithelium and surrounded by circular muscles. In the distal half of the copulatory organ, the seminal vesicle connects directly to a sclerotised stylet (Figs. 2, 4D: st; 3A). The stylet is a simple, thin-walled funnel, curved at an angle of about 90° at its midpoint. The stylet is 33 µm long and 9 µm wide proximally. It connects to a long male duct, which opens in the oral cavity (Fig. 2B: oc).
The female genital system consists of a large, curved ovary (Fig. 2: ov), positioned at the midbody, dorsally to and in front of the intestine. A female duct or gonopore was not observed. Instead, the oviduct appears to connect directly to the intestinal lumen. It is assumed that eggs are deposited in the intestinal lumen and expelled from the body via the mouth. Eosinophilic glands are present in the region where the ovary connects to the intestine. In the same area, vesicles with sperm were observed in the intestinal wall (Fig. 2A: isv). Possibly, these vesicles are resorptive and function as a bursa. The posterior half of the body is almost completely taken up by a lobed or branched vitellarium (Fig. 2B: vit).
description: Published as part of GOBERT, STEFAN, ARMONIES, WERNER, DIEZ, YANDER L., JOUK, PHILIPPE, MONNENS, MARLIES, REVIS, NATHALIE, REYGEL, PATRICK, SMITH, JULIAN III, STEENKISTE, NIELS VAN & ARTOIS, TOM, 2022, Orostylis gen. nov., a new genus of Dalytyphloplanida with seven new species (Platyhelminthes: Rhabdocoela), pp. 29-46 in Zootaxa 5115 (1) on pages 31-33, DOI: 10.11646/zootaxa.5115.1.2, http://zenodo.org/record/6346911