Dreuxiola, 2009

Schockaert, Ernest R., Curini-Galletti, Marco, Ridder, Wouter De, Volonterio, Odile & Artois, Tom, 2009, A new family of lithophoran Proseriata (Platyhelminthes), with the description of seven new species from the Indo-Pacific and South America, and the proposal of three new genera, Zoological Journal of the Linnean Society 155 (4), pp. 759-773 : 764

DREUXIOLA PHILLIPI SP. NOV.

Diagnosis: Species of Dreuxiola with about 25 testes, a very long and coiled stylet, about 250-Mm long, and two groups of four needles, each 35–37-Mm long. The vagina ends with a sclerotized (‘cuticular’) tube.

Occurrence: Port aux Français, Kerguelen (Territoire Australe Français), on the flat beach east of the port; fine sand in the mid-littoral, dominated by nematodes.

Material studied: Observations were made on the living animals and two whole mounts (one of them indicated as the holotype, SMNH 7353, the other indicated as a paratype UH 381); four series of sections, from which only two contain relevant information (UH 382–385).

Etymology: Genus and species are named in honour of Prof. Philippe Dreux (Université Pierre et Marie Curie, Paris): entomologist and noted authority on the wingless Curculionidae (Coleoptera) of the French Austral Territories.

Description: The animals are very long and slender, 3–4-mm long, with some anterior sensory bristles. Adhesive papillae were not seen in the whole mounts, nor were they seen in the sections. The brain is encapsulated, and there is a clear extension of the gut over the brain. The pharynx is directed ventrally, is slightly lobate, and is placed at two-thirds of the body length ( Fig. 5 ). The epidermis is 1-Mm-thick ventrally and 1.5-Mm-thick dorsally; cilia are 2-Mm long.

The ovaries are just in front of the pharynx, and most vitellarian follicles are behind the pharynx, extending over about one-third of the post-pharyngeal body part. Behind the last follicle, the two ovovitelloducts join into the common female duct, which looks very muscular and swollen in living animals, is filled with sperm, and clearly functions as a copulatory bursa. The vagina opens roughly in its middle, with a little sclerotized tube that is about 50-Mm long ( Figs 6 , 7 ). In the sections the vaginal duct appears as a narrow tube with a strongly muscular wall, surrounded by loose tissue that is also surrounded by some longitudinal muscles. In one of the sectioned animals this part is highly swollen, forming a vesicle that is also seen in the living animal and in the whole mounts ( Fig. 6 ). Further backwards, the female duct narrows towards the female pore that is found at three-quarters of the postpharyngeal body part. From the female pore the genito-intestinal duct departs towards the resorbing bursa.

The male system consists of about 25 testes in a row, extending from some distance behind the brain down to the level of the ovaries ( Fig. 5 ). The copulatory organ lies between the female pore and the vagina, and has an astonishing construction ( Figs 6– 9 ). The prostate vesicle has the proximal pole directed forwards, where the paired seminal vesicles enter, and the distal pole is directed backwards; distally, the prostate vesicle tapers, and recurves by almost 180°. The stylet starts with a bent proximal end, so that the stylet becomes directed forwards. The seminal vesicles lie next to the prostate vesicle and join each other in a short seminal duct that can be followed in the prostate vesicle. Here, its epithelium forms the prostate glands, of which the cell bodies with nuclei are outside the vesicle, and some nuclei are inside the bulb. The stylet is very narrow and very long. It makes a loop and enters the expanded male atrium. The proximal part of the atrium is swollen and contains a net-like glandular tissue surrounded by a thin muscle layer. Two groups of needles seem attached to this accessory glandular bulb. The stylet enters the male atrium roughly in the middle of this glandular bulb. The stylet is about 250-Mm long in the two whole mounts; the needles are 40–50-Mm long. These needles seem to be very slightly sclerotized, and are rather difficult to discern in whole mounts. Nevertheless, it could be observed that the needles are arranged symmetrically in two groups, each consisting of a shorter, curved needle at the outside, and a thicker, straight needle in the middle (both about 40-Mm long), and with two slender and moderately curved needles of about 50-Mm long in between (measurements from the two whole mounts).

Figures

Figure 5. A living animal of Dreuxiola philippi sp. nov. Refer to the Appendix for a list of abbreviations.

Figure 6. Postpharyngeal genital organs of Dreuxiola philippi sp. nov. as in the whole mount, but also as they have been seen in the living animal. Refer to the Appendix for a list of abbreviations.

Figure 7. Reconstruction of the postpharyngeal genital organs of Dreuxiola philippi sp. nov., seen from the right. Refer to the Appendix for a list of abbreviations.