Brunetorhynchus microstylis, Schockaert, Ernest R., Martens, Paul M., Revis, Nathalie, Janssen, Toon, Willems, Wim & Artois, Tom J., 2014

Schockaert, Ernest R., Martens, Paul M., Revis, Nathalie, Janssen, Toon, Willems, Wim & Artois, Tom J., 2014, A new genus with six new species of Typhlopolycystidinae Evdonin, 1977 (Platyhelminthes, Kalyptorhynchia, Polycystididae), Zootaxa 3755 (3), pp. 259-272 : 262-265

Brunetorhynchus microstylis n. sp. Schockaert, Revis & Artois

( Fig. 2 )

syn. Brunetorhynchus microstylis Krznaric et al. , nomen nudum in Willems et al (2009) Holotype. A whole mount from Cerbère, France, Bay of Terrimbou, north side of the bay, near Les Aloès, fine to coarse-grained clean sand, with little silt, 8 m deep (29 July 2007) (SMNH 7837).

Paratypes. Three whole mounts and a serially-sectioned specimen from the same locality (13 July 2007, 19 July 2007) (HU, nos 542–545).

Other material and localities. Two whole mounts and five serially-sectioned specimens (HU, nos VI.2.6– VI.2.12), France, Bay of Marseille, “La Pierre Joseph” near to Isle Plane, 17 m deep, fine-grained sand (11 May 1967 and 16 February 1968, leg. M. Brunet). Six whole mounts (HU, nos VI.2.13–VI.2.18), Bay of Calvi, Corsica, France, various localities in the harbour of STARESO, fine-grained sand, 6–32 m deep (12 June 1982, 8 and 11 March 1983, 19 May 1983, 17 September 1983). Three whole mounts and a sectioned specimen from Banyuls-sur-Mer (HU, nos VI.2.19–VI.2.22), France, in front of the Laboratoire Arago, (Observatoire Océanologique de l’Université Pierre et Marie Curie - Paris 6): La Peleteuse, ridge of sea floor, coarse-grained sand with little silt, 15 m deep (18 July 2007), L’Herbier, sandy bottom past the fields of sea grass ( Posidonia ) (at the end of the longest concrete pipe), mixed sand with some silt and stones, 10 m deep (8 July 2008), Ile Grosse, near rocks close to jetty, fine-grained sand and dead seagrass, 14 m deep (26 July 2008). Three whole mounts and one mediocre serially-sectioned specimen (HU, nos VI.2.23–VI.2.26) from Sardinia, Italy, Costa Paradiso, Grotta Niedda, 41°03'08.84"N 8°56'15.71"E, very coarse-grained sediment and shell gravel, 32 m deep (11 September 2010). One whole mount (HU, no VI.2.27) from Sardinia, Italy, Punta Negra, coarse-grained sand from channel, 30 cm deep (22 August 1994). One whole mount ( SMNH 134633) from Kalkgrund, Sweden, 58°55’26.46”N 11°02’25.92”E - 58°55’27.42”N 11°02’37.38”E (coordinates of start and stop of dredge), silty calcareous sand, 15–19 m deep, 3 September 2007 (Willems et al. 2009). One whole mount (HU, no VI.2.28) from Faro, Portugal, in the Ria Formosa, 36° 58' 45"N, 7° 51' 49"W, mid-littoral of the beach with relatively coarse and clean sand (7 October 2013). Two whole mounts from the Island Lanzarote (Canary Island, Spain), one (HU, no VI.2.29) from Mala, 29°05' 0.53"N 13°26' 59.09"W, medium coarse calcareous sand from an open, steep slope; sample taken close to black coral, 48 m deep (8 October 2011) and the other (HU, no VI.2.30) from off Punta Jameos del Agua, 29°9'25.10"N 13°25' 37.89W, medium sand, clean, with Caulerpa , 38 m deep (15 October 2011).

Other localities. Banyuls-sur-Mer, France, Bay of Les Elmes, in the middle of the bay, fine, clean sand, 6 m deep (5 August 2008), Cavall Bernatt, coarse-grained sand, 19 m deep (8 July 2010) and Cap L’Abeille, 18 m deep, bottom with large ripple marks, sample taken on top of ripple mark, coarse sand with small and larger stones and shell debris, with high silt content (3 May 2012). Sardinia, Italy, Isola Budelli, Cavaliere, 41°17’29.76”N 9°20’52.04”E medium- to fine-grained, clean sand, 35 m deep (7 September 2010).

Etymology. The stylet (accessory stylet type II) is smaller than in most other species of Brunetorhynchus .

Diagnosis. Species of Brunetorhynchus with a stylet 40–50 µm long and 6–7 µm wide at the proximal opening, bent about in the middle, with a pointed distal tip and a collar at one side of the proximal opening. A well developed prostate vesicle type III fills the proximal part of the male atrium.

Description. Colourless to slightly pink animals, 0.5–1 mm long, with eyes. The gross anatomy is very similar to that of B. deconincki n. sp. but the proboscis is only 1/6th of the total body length and the cone retractors seem to be arranged in three groups.

The genital pore is at 80%, somewhat more caudally in the sectioned specimens, and guarded by a welldeveloped sphincter. The common genital atrium starts as a narrow duct that first receives the uterus frontally and then continues into a wide space in which the male atrium enters at the anterior side and the female duct at the dorsal side. The common atrium, the most distal part of the male atrium and the female duct are lined with a relatively high and nucleated epithelium and are surrounded by thin muscles fibres.

The single testis is just behind the pharynx and at the left side, the stylet is at the right side, 41–51 µm long and 6–7 µm wide at the proximal opening (m = 47 µm, n = 16; 49 µm in the holotype; only the stylet of the individual from Faro exceeds this range with 62 µm). It ends in a sharp point and is bent over about 130° at about one third from its proximal end. The proximal opening is approximately in the middle of the proximal third and its rim has a large, thin collar at one side. As far as it could be seen on this small stylet, two ridges depart from the other side of the opening, join soon and open again to form the distal opening. The shape of the stylet can be rather different depending on the degree of compression and/or the orientation in the slide (see Fig. 2 I–O). The duct of the accessory vesicle type II enters the stylet through its proximal opening, while the seminal duct ends in the collar. The prostate vesicle (type III) is situated in the proximal part of the male atrium and mainly at the concave side of the stylet. The secretion is slightly basophilic and in most sectioned specimens two nuclei were seen. The part of the male atrium that contains the prostate glands is surrounded by longitudinal muscles that insert on the wall of the male atrium distally from the prostate glands. From here on the male atrium is surrounded by strong circular muscles, which gradually become thinner towards the common genital atrium.

The female duct (type I) is a short and wide connection between the common atrium and the oviduct. As in B. deconincki n. sp. this oviduct is transformed into a resorbing bursa caudally and receives the ovary and the single vitelloduct anteriorly. Dorsally there is the pyriform seminal receptacle, which has a strong circular muscle sheath where it is attached to the oviduct. The size of this seminal receptacle can vary considerably. No glands were seen at the exit towards the female duct.

Figures

FIGURE 2. Brunetorhynchus microstylis n. sp. (A) The living animal as drawn by M. Brunet. (B) Micrograph of a living specimen from Sardinia. (C) Posterior end of a living animal from Lanzarote. (D) The male atrial organs in the living animal. (E) Reconstruction of the atrial organs from sagittal sections, seen from the right. (F – H) The seminal receptacle of three individuals (in whole mount, H in the holotype). (I – O) The stylet: (I, M) of the holotype from Cerbère, (J) of an individual from Marseille, (K) one from Sardinia, (L) the one from Kalkgrund (N) one from Lanzarote, (O) one from Corsica (scale bars = 25 µm).