Sabatieria exilis Botelho, Silva, Sobral & Fonsêca-Genevois, 2009, sp. n.

Sabatieria exilis sp. n. (Figures 2, 3, 4; Table 1)

Material Studied: 4 males, 2 females, 2 juveniles.

Type material: Male holotype, slide MNRJ 318. Female paratype, slide MNRJ 319; 3 male paratypes, slides 90–92 NM LMZOO-UFPE; 1 female paratype, slide 93 NM LMZOO-UFPE; 2 juvenile paratypes, slides 94–95 NM LMZOO-UFPE.

Type locality: Station No. 49 at 750 m depth in silt-clay sediments collected in June 2003. The type station was in the Campos Basin off Rio de Janeiro, Brazil, in silt-clay sediments (see Appendix 1).

Etymology. The Latin name exilis = slender, refers to the narrow maximum width of this species.

Description. holotype: Body cylindrical, medium-sized, attenuated at both ends. Cuticle with transverse rows of small dots, lateral differentiation of larger, equally spaced dots. Short somatic setae. Rounded head with anterior sensilla arranged in three crowns: six minute internal labial papillae, six minute external labial papillae and four cephalic setae. Amphidial fovea spiral, with 1.5 turns situated at level of cephalic setae. Buccal cavity minute. Pharynx clavate and gradually expanding in the last third, towards the posterior end but without distinct bulb; the anterior end surrounds the posterior part of stoma, which is weakly cuticularized. Cardia short, pear-shaped. Nerve ring slender, located somewhat anterior to middle of pharynx and anteriorly to secretory-excretory pore. Ventral gland present on posterior end of pharynx and beginning of intestine.

Male reproductive system diorchic, with opposed and outstretched short testes. Anterior testis situated on the left, and the posterior testis on the right, side of the intestine. Slender cuticularized paired spicules of equal lengths and widths and slightly curved ventrally; proximal half with mid-septum and presence of alae. Several glandular cells are arranged around the spicules. Small gubernaculum with narrow cuticularized apophysis. Six minute pore-like pre-cloacal supplements, equally distributed; pre-cloacal setae present. Spermatozoa oval, 5 µm long. Tail conico-cylindrical with swollen tip. Three caudal glands present in postanal region, ending in a spinneret. Two caudal setae, 2.5 µm long.

S. exilis S. fidelis * Length of cylindrical portion in the tail Female paratype: The females are quite similar to the males, although some minor morphological differences can be observed. Total body length and head diameter similar to males, tail somewhat shorter than male. Reproductive system didelphic, amphidelphic, with outstretched ovaries. Anterior ovary to the left and posterior ovary to the right of intestine. Distal and proximal parts of uterus with oocyte 25–34 µm long. Vagina fine-walled, with dilatory muscle.

Diagnosis. Sabatieria exilis sp. n. can be distinguished by the constriction of the pharynx at the level of the cephalic setae, the small uniformly rounded head, the minute buccal cavity, and the number of turns in the amphidial fovea (1.5).

Discussion. Sabatieria exilis sp. n. resembles Sabatieria stekhoveni in the spicule shape and in possessing a pre-cloacal seta, but can be distinguished from the known species especially by the total length (940–1178 µm in S. exilis sp. n. versus 1547–1700 µm in S. stekhoveni), number of amphidial fovea turns (1.5 versus 3.25), length of the tail (3–4 versus 4–4.5 cloacal diameter). With Sabatieria pissina, S. exilis shares the short cephalic setae (2–2.5 in S. exilis versus 2.2–2.5 µm in S. pissina), small dots on the cuticle, spicule length and shape (33–35 versus 29–31 µm), and apophysis length (9–11 versus 9.7 µm), but can be differentiated from this species by the total length (940–1178 µm in S. exilis sp. n. versus 657–777µm in S. pissina), tail length (64–93 µm in S. exilis sp. n. versus 50–62 µm in S. pissina); number of turns in amphidial fovea (1.5 versus 2.75–3), de Man index a (28.7–46 versus 21.5–27.3) and absence of supplements in S. pissina.

In relation to S. propissina, this new species is similar in the shape of spicule and its length in relation to the cloacal diameter (1.5–2 in S. exilis sp. n. versus 1.3–1.4 in S. propissina). The length of the gubernaculum apophysis is also similar (9–11 in S. exilis sp. n. versus 10–11 µm in S. propissina). They can be distinguished by the total length (940–1178 µm in S. exilis sp. n. versus 670–780 µm in S. propissina), length of pharynx (136–162 µm in S. exilis sp. n. versus 110–118 µm in S. propissina) and cephalic diameter (7–8 µm in S. exilis sp. n. versus 5.8–6 µm in S. propissina).