Coelogynopora schockaerti, Jouk & Revis & Artois, 2019, Jouk & Revis & Artois, 2019

Jouk, Philippe E. H., Revis, Nathalie J. P. & Artois, Tom, 2019, Coelogynopora schockaerti n. sp. (Proseriata: Coelogynoporidae), a remnant of a platyhelminth coldwater fauna in the northwestern Mediterranean?, Zootaxa 4686 (3), pp. 409-418 : 410-411

Taxonomical account

Localities : Portbou, Northern Spain, on the beach near the quay towards the harbour, at the water edge, in the surf zone; coordinates 42.426626, 3.162143 (42°25’35.9”N, 3°09’43.7”E) (Type locality) on 13 & 20/04/2011 and 02/04/2012, and at the same location on 02/04/ 2012 in water depth of about 50 cm. Most individuals were found in coarse sand mixed with seagrass detritus, some in fine sand .

Material: Twenty-one animals studied alive. One whole mount designated holotype (SMNH type-9199), nine other whole mounts paratypes (HU 742-750). Three squeezed animals for detailed study of the sclerotised spines (HU 751-753). Two serially-sectioned specimens, also paratypes (HU 754-755).

Etymology. The species is named after Prof. Em. Dr. Ernest Schockaert, who introduced all three authors into the fascinating world of the Plathyhelminthes. His great knowledge of this taxon, combined with his enthusiasm and preparedness to share his knowledge has always been, and still is, a source of inspiration to them.

Description. Adult live animals ( Fig. 1 A and B ) are 5–9 mm long and 0.3–0.5 mm wide. As is the case in most other coelogynoporids, the anterior body tip is slender and provided with short sensory bristles. Anterior to the encapsuled brain (br) there is a statocyst (sta) consisting of one statolith accompanied by four lithocytes (“Nebensteinchen” Ax, 1956; terminology of Ehlers & Ehlers, 1990). All along the body, oblong green-yellowish refracting subepidermal glands are present. The largest numbers of glands are located in the posterior and anterior body ends.

The pharynx (ph) is located in the posterior quarter of the body ( Fig. 1 A and B ). It is oriented dorso-ventrally and very contractile, changing from very oblong to almost oval in diameter following the stretching and contracting movements of the body. The intestine extends to the brain rostrally and bears a gut diverticulum extending in front of it.

Eighty to up to more than 130 testis follicles ( Fig. 1A , te) form a double median row in the anterior two-thirds of the body, starting a little posterior of the brain capsule. The ovaries (ov) are lateral, just rostral to the pharynx and contain several germocytes. The vitellaria (vit) extend as two lateral strings, reaching from a little posterior of the brain capsule to just anterior to the ovaries in some specimens or to just in front of the male copulatory organ (cop) in others.

The male copulatory organ ( Fig. 1A, C and 2F ) is located in the posterior body end, well behind the pharynx. The paired seminal vesicles (sv) are lateral and extend caudally almost to the posterior body tip. They join just anterior to the accessory spines (asp), forming a common ejaculatory duct, which enters the male copulatory bulb. In some specimens, the common ejaculatory duct widens in the distal half of the bulb to form a small, ovoid vesicle ( Fig. 1C ). Three different types of spines are present in the bulb: a pair of main spines with a “cap”, accompanied by two pairs of shorter, more slender spines ( Fig. 2A and B ). The main spines are composed of two separate but closely associated parts ( Fig. 2A , 1a and 1b ), 54–95 µm long (x̄ = 76 µm, n= 28). The inner spine ( Fig. 2A , 1a ) is narrow at its base, and gradually widens towards its tip. At the tip, the inner spine has a kind of “cap”, which is connected to the muscles of the bulb with several appendages ( Fig. 2A , ap). The outer spine ( Fig. 2A , 1b ) runs completely parallel with the inner one, its tip being encased in the common cap. The accompanying spines are composed of two different pairs: a first pair of straight spines with a blunt tip ( Fig. 2A, 2 ), 37–61 µm (x̄ = 51 µm, n= 27) long, located dorso-medially of the main spines, and a second pair of slightly bent needles with pointed tip ( Fig. 2A , 3) positioned laterally from the main spines, 41–70 µm (x̄ = 55 µm, n= 26) long. The smaller spines are found in the smallest individuals, the larger ones in the larger animals. This seems to be the rule in most plathelminth species ( Brüggemann, 1986; 1988).

The two accessory spines ( Figs. 1C , 2C, D and F ) are just caudal to the male copulatory organ and are connected to each other by strong muscles. These spines are gutter-shaped, completely open at their base, and gradually close towards the distal part, where the tip is bent at a right angle towards the middle of the animal. The tip forms a kind of elongated, pointed cup, open at its distal end. The proximal part is 36–64 µm long (x̄ = 53 µm, n= 30) up to the bend and 7–17 µm (x̄ = 11 µm, n=30) wide at the base and becoming somewhat less wide towards the bend. The tip is 15–28 µm (x̄ = 23 µm, n= 28) long. Strings of fine-grained glands ( Fig. 1C, g ) join at the tip of the accessory spines and enter the tip of the accessory spine.

Aberrant specimens were encountered, either with three main spines (but normal number of other spines and accessory spines; Fig. 2 E ), or with three accessory spines (but normal number of spines).

Posterior to the accessory spines, a muscular female duct (fd) leads to the seminal bursa ( Fig. 1A and C , sb). Younger live individuals did not show a bursa. Large glands join at and surround the distal part of the female duct.

The gonopore ( Fig. 1C , go) is ventral in between the male copulatory bulb and the accessory spines.

Figures

FIGURE 1. Coelogynopora schockaerti n. sp. A. Drawing of the living animal. B. Living animal at low magnification. C. Drawing of the post-pharyngeal parts of the genital system in the living animal.

FIGURE 2. Coelogynopora schockaerti n. sp. A. Spines of the male copulatory bulb. B. Micrograph of the spines of the male copulatory bulb of a living animal. C. Accessory spines of the male copulatory organ. D. Micrograph of the accessory spines of the male copulatory organ. E. Micrograph of the spines of the male copulatory bulb of a living animal with three main spines. (scale bars = 20 µm). F. Micrograph of the hard parts of the male copulatory organ. (scale bar = 50 µm)