Desmodora paraconica, Larrazábal-Filho, Alexandre L., Silva, Maria Cristina Da & Esteves, André M., 2015

Larrazábal-Filho, Alexandre L., Silva, Maria Cristina Da & Esteves, André M., 2015, Four new species of free-living marine nematodes of the family Desmodoridae (Nematoda: Desmodorida) and a redescription of Desmodora nini (Inglis, 1963) from the continental shelf off northeastern Brazil, Zootaxa 4021 (1), pp. 63-92 : 80-81

Desmodora paraconica sp. n.

(measurements in Table 5 , Figs 11 , 12,13).

Type material. Holotype Male adult MNRJ 348 (04°45’00”S, 036°30’00”W) collected in June 2009, in the Potiguar Basin, between 45 and 100 m. Sediment: terrigenous muds. Gear: Van Veen grab and corer.

Paratype female. Adult MNRJ 349 (03°00’00”S, 038°45’00”W) in the Potiguar Basin, between 45 and 100 m. Sediment: fine to coarse bioclastic sand. Gear: Van Veen grab and corer.

Other paratypes: 1 male (184 LMZOO-UFPE) and 2 J1 (185 LMZOO-UFPE), collected on the same date as the holotype.

Etymology. The name refers to the similarity of the species to Desmodora conica Vitiello, 1971 .

Description. Holotype male ( Figs 11 , 13 ) Body long and cylindrical, yellowish brown in colour, with strong cephalic capsule and conical-cylindrical tail. Cuticle annulated except on cephalic capsule and final portion of tail. Annulation on anterior body 2 µm, in median region 1.5 µm and in posterior region 1 µm. Short sparse somatic setae irregularly distributed along body. Rounded head and strongly sclerotized cephalic capsule. Fovea amphidialis loop-shaped. Buccal cavity with one dorsal tooth and one smaller ventrosublateral tooth. Six lips with 12 folds. Anterior sensilla arrangement: six inner labial papillae, six outer labial papillae and four cephalic setae above fovea amphidialis. Subcephalic setae absent. Pharynx with pyriform endbulb, with sclerotized lumen divided into distinct regions. Nerve ring not observed. Ventral gland and secretory-excretory pore not observed. Triangular cardia inserted in intestine. Reproductive system with outstretched testis. Large globular sperm cells. Patch region observed in vas deferens. Spicules slender and strongly arched, with rounded capitulum, velum not observed. Laminar of gubernaculum positioned dorsally, without apophysis. Three caudal glands. Tail conical-cylindrical, distal portion without annulations. Spinneret conical.

Female ( Figs 11 , 12 ) Similar to male, but ventro-sublateral tooth difficult to see. Reproductive system with two paired opposite and reflexed ovaries. Vulva a transverse slit. Vagina vera short, vagina uterina with sphincter muscle. Tail conical-cylindrical. Spinneret conical.

Juveniles Four juveniles found, all in in first stage of development. Identical to adults ( Fig. 13 ) but smaller. Cephalic arrangement difficult to see.

Diagnosis and relationships. Desmodora paraconica sp. n. is characterized by having four cephalic setae above the fovea amphidialis, short sparse somatic setae, spicules slender and strongly arched, with gubernaculum laminar and positioned dorsally, without apophysis, and conico-cylindrical tail.

In having a long tail, Desmodora paraconica sp. n. is similar to D. poseidoni Steiner, 1916 ; D. alberti Verschelde et al., 1998 ; D. scaldensis De Man, 1889 ; D. conica Vitiello, 1971 and D. masira Warwick, 1973 . It differs from D. poseidoni , D. alberti and D. scaldensis in the shape of the spicules. Desmodora poseidoni has long spicules, and in D. scaldensis the spicules are slender and slightly curved. Desmodora conica is similar to D. paraconica sp. n., but differs in the buccal cavity, having only one dorsal tooth and eight rows of somatic setae, and in the shape of the spicules, which are thin, arched and longer. Recently, Moura et al. (2014) described D. profundum from the Campos Basin, Rio de Janeiro, Brazil. It has a loop-shaped fovea amphidialis; a rounded head with a well-defined head capsule; oral cavity with two tiny teeth; globular sperm cells; and a long tail. The main difference between D. paraconica sp. n. and D. profundum is that the latter has long thin spicules and six rows of somatic setae.

This new species also resembles members of the genus Bolbonema in the shape of the cephalic capsule and fovea amphidialis. However, the descriptions of Bolbonema are brief and inadequate. In addition, there is no agreement among the authors. In his brief description Cobb (1920) did not mention the cephalic setae, which were discussed by subsequent authors. Verschelde et al. (1998) stated that the cephalic setae are located posterior to the fovea amphidialis; but Decraemer & Smol (2006) stated that the cephalic setae are inserted in the base of the head capsule. Tchesunov (2014) agreed with Verschelde et al. (1998). The specimens presented here have the cephalic setae positioned in the upper level of the fovea amphidialis.

Figures

FIGURE 11. Desmodora paraconica sp. n. Holotype MNRJ 348 A: overview (male). B: anterior region. Paratype female MNRJ 349 C: overview (female). D: copulatory apparatus. E: vulva opening. F: head region (female). G and H: tail region (female and male respectively).

FIGURE 12. Desmodora paraconica sp. n. Paratype female MNRJ 349 A: overview. B: anterior region. C: head region. D: ovary and vulva opening. E: tail region.

FIGURE 13. Desmodora paraconica sp. n. Holotype MNRJ 348 - A: overview. B and D: head region. C: anterior region. E: tail region. F: copulatory apparatus. Paratype Juvenile I - G: head region. H: overview.