Hoplopera isis Houben, Proesmans & Artois, 2022

Houben, Albrecht M., Monnens, Marlies, Proesmans, Willem & Artois, Tom J., 2022, Limnoterrestrial ‘ Typhloplanidae’ (Rhabdocoela, Platyhelminthes), with the description of four new species and a new genus, European Journal of Taxonomy 798, pp. 70-102 : 86-88

Hoplopera isis Houben, Proesmans & Artois sp. nov.

urn:lsid:zoobank.org:act:4DA3359A-D279-4286-B7B0-822382D258F7

Fig. 7A–C

Diagnosis

Dark species of Hoplopera , about 0.8 mm long with inconspicuous tail glands. Dermal rhabdites small, adenal rhabdites in two tracks. Atrial glands present. Spindle-shaped testes. Copulatory organ 20 µm long, without sclerotised structures. Bipartite bursa with sclerotised structure containing two groups of parallel, vertical rods, separated from each other by vertical bars, as a whole resembling a fish pot. Female duct forming a seminal receptacle.

Etymology

The species epithet is dedicated to Isis Houben , first daughter of the first author (A.M. Houben).

Material examined

Holotype AUSTRIA • 1 spec., studied alive and horizontally sectioned; south of Graz, between Glashütten and Trahütten; 46°49′46″ N, 15°06′09″ E; 23 Aug. 2011; A.M. Houben and W. Proesmans leg.; moss growing in a small stream in a pine forest; KV.688 ; FMNH.

Paratypes AUSTRIA • 5 specs, studied alive, one of which whole mounted; same collection data as for holotype; paratype no. 822 ; HU.

Description

Specimens are about 0.7–0.9 mm long. The body is rounded anteriorly and possesses a small tail provided with small, inconspicuous tail glands ( Fig. 7C : tg). Rostrally, sharply pointed adenal rhabdites ( Fig. 7B : ar) are arranged in two groups. Very small dermal rhabdites occur all over the body. The paired protonephridiopores ( Fig. 7A : pp) lie posterior and lateral to the mouth. The rosulate pharynx is located just behind the middle of the body ( Fig. 7A : ph).

The gonopore ( Fig. 7B–C : gp) is situated at ±80% of the body and connected to a genital atrium ( Fig. 7A–C : ga) that is lined with a high epithelium and surrounded by muscles of uncertain orientation. At its posterior side, the genital atrium receives a large group of eosinophilic glands ( Fig. 7A–C : ag).

Two small, spindle-shaped testes ( Fig. 7A : t) lie in front of the pharynx ( Fig. 7A : ph) and ventral to the paired vitellaria ( Fig. 7A, C : vi). In some specimens, one testis seems bigger than the other one. The paired vasa deferentia ( Fig. 7B–C : vde) enter the egg-shaped copulatory organ laterally. Two layers of spiral muscles surround the 24µm long copulatory organ ( Fig. 7A : co), which bears an intracapsular seminal vesicle ( Fig. 7B–C : vs) and an ejaculatory duct ( Fig. 7B–C : de). Coarse-grained intra- ( Fig. 7B– C : gg1) and extracapsular ( Fig. 7C : gg2) eosinophilic glands are associated with the copulatory organ. The relatively long male duct ( Fig. 7C : md) receives the bursa ( Fig. 7A–C : bu) before entering the genital atrium ( Fig. 7A–C : ga). This bipartite bursa consists of an 18 µm long, thin-walled proximal part containing sperm and a 22 µm long distal part, which could be considered the bursal stalk ( Fig. 7B–C : bs). This stalk is surrounded by circular muscles and contains a sclerotised structure ( Fig. 7B : ss) that resembles the structure of a fish pot. It consists of vertical rods that are divided into two groups by a horizontal bar. The proximal and distal part are also delimited by a horizontal bar. As a whole, this bursal stalk is wrapped in a loose matrix surrounded by circular muscles.

The vitellaria ( Fig. 7A, C : vi) extend from the anterior third of the body to the posterior end where they meet. The oviduct broadens and becomes a seminal receptacle ( Fig. 7A–C : rs), which further becomes a long female duct ( Fig. 7C : fd), lined with a high, nucleated epithelium and surrounded by muscles. The vitelloduct was not observed with certainty, although it is probably an unpaired one that meets the oviduct.

Discussion

See the general discussion on the genus Hoplopera .

Remarks

The hard parts and copulatory structures are not visible on the whole-mounted specimen. Therefore, we designate a serially sectioned specimen as holotype.

Figures

Fig. 7. Two species of Hoplopera Reisinger, 1924. A–C. Hoplopera isis Houben, Proesmans & Artois sp. nov. A. Internal organisation of a live specimen. B. Organisation of the genital system of a live specimen. C. Reconstruction of reproductive organs based on horizontal sections. D–F. Hoplopera opaca Reisinger, 1924. D. Internal organisation of a live specimen. E. Organisation of the genital system of a live specimen. F. Reconstruction of reproductive organs based on sagittal sections.