Leptonemella undetermined

Armenteros, Maickel, Ruiz-Abierno, Alexei & Decraemer, Wilfrida, 2014, Taxonomy of Stilbonematinae (Nematoda: Desmodoridae): description of two new and three known species and phylogenetic relationships within the family, Zoological Journal of the Linnean Society (Zool. J. Linn. Soc.) 171 (1), pp. 1-21 : 10-11

LEPTONEMELLA BREVIPHARYNX SP. NOV.

Measurements: Table 3; Figures 5 , 6 .

Type material: Holotype male, deposited at the Center for Marine Collections, National Aquarium (Habana, Cuba) with collection number ANC_04.064 . Paratypes: one male paratype, collection number CN _1525.2 , one female paratype CN _1525.9, and two paratype juveniles CN _1516.3 and CN _1554.3 deposited in the Nematode Collection at Centro de Investigaciones Marinas, Universidad de La Habana (Habana, Cuba). Three deposited at the Royal Belgian Institute of Natural Sciences (Brussels, Belgium): collection numbers RIT 818 (male), RIT 819 (two juveniles) .

Habitat type: Coralline sand in the reef lagoon, ∼ 2 m depth, Punta Francés coral reef (21°36′29.68′′N, 83°10′34.40′′W).

Etymology: The specific epithet (i.e. brevipharynx ) is a combination of the Latin words ‘ brevis ’ (meaning short) and ‘ pharynx ’; it refers to the characteristic short length of the pharynx of the species compared with the body length.

Description: Body habitus filiform and usually tightly coiled; often body diameter decreasing posterior to the pharyngeal region. Cuticle finely striated (annuli ∼0.3 μm width). Anterior profile of the head rectangular, head capsule clearly demarcated, inner cuticular wall with vertical rods that give a punctuated surface pattern under LM. Inner labial sensilla papilliform (∼1 μm long), outer labial sensilla papilliform (1–2 μm long), four cephalic sensilla setiform (13–18 μm long), four circles of eight subcephalic setae (10–12 μm long), very close and posterior to the cephalic setae. Eight longitudinal rows of somatic setae (8–10 μm long) running from cervical region to tail, each somatic seta connected to an epidermal gland. Amphidial fovea an open spiral of 1.25 turns, located at head border, appearing almost frontal in position, diameter approximately 0.4 c.b.d. Buccal cavity minute, no sclerotized structures. Pharynx muscular, very short, with almost rounded posterior bulb, cardia rounded and inconspicuous; nerve ring at mid-pharynx. Ventral gland not observed. Tail conical, final portion without striae but with internal vertical rods (similar to those Holotype measurements are included in the male averages and ranges.

c′, tail length relative to the anal body diameter; c.b.d., corresponding body diameter; J, juveniles; N, number of specimens; V %, distance (relative to body length) of vulva to anterior apex.

All measurements are in μm.

*indicates that measurements could not be taken (or with higher associated error) because of the position of the specimens.

in the head capsule); tail shorter in males (c′ = 2.6) compared to females (c′ = 3.0); caudal glands with spinneret present and three apertures and a central pore; we could not ascertain how glands connect to the central pore. Coccoid-shape bacteria covering most of the body.

Male monorchic, anterior testis to the left of the intestine. Spicules curved, paired, with marked capitulum; gubernaculum with short corpus and clear dorsal apophysis, hooked at tip; no precloacal supplements.

Female didelphic, ovaries antidromously reflexed; vulva not sclerotized, located at mid-body.

Diagnosis: The new species is characterized by the shape of the amphidial fovea as an ‘open’ spiral, very short pharynx b> 39; gubernaculum with short corpus 22–29 μm long and dorsal apophysis, hooked at tip; tail short in males, less than 120 μm (<3 a.b.d.).

Differential diagnosis and relationships: Le. brevipharynx sp. nov. belongs to the genus Leptonemella Cobb, 1920 because of the clearly demarcated cephalic capsule not surrounded by fine but distinctive cuticle striation, circles of relatively long subcephalic setae on the cephalic capsule, amphidial fovea as an ‘open’ spiral (i.e. not tightly coiled) located in laterofrontal position and the coccoid-shape ectosymbiotic bacteria and gubernaculum without dorsocaudal apophysis.

Hoschitz et al. (1999) recognized four valid species of Leptonemella , transferred Le. sigma Gerlach, 1963 to the genus Laxus Cobb, 1920 , and proposed two new species (Le. juliae and Le. vestari ). These authors considered the following diagnostic features as the most important for the genus ( Hoschitz et al., 1999: table 1): the amphidial fovea shape (in females); length of cephalic, subcephalic, and somatic setae; and shape of the gubernaculum. Riemann et al. (2003) made an outline of the genus recognizing seven species, including a new one (Le. vicina ), and discussed valuable information about ecology, distribution, physiology, and taxonomy. The authors stressed the difficulty in discriminating amongst the known species because of the minor differences amongst them. The most recent revision of the Stilbonematinae ( Tchesunov, 2013) recognized seven species (see above) and also supports the taxonomy proposed by Riemann et al. (2003).

Leptonemella brevipharynx sp. nov. can be discriminated from the other seven species based on three unique features: the very short length of the pharynx, the very short length of the tail in males, and the shape of gubernaculum with curved, hook-like proximal end.

Figures

Figure 5. Leptonemella brevipharynx sp. nov. A, anterior region, paratype 1♂; B, habitus, holotype ♂; C, tail region, holotype ♂; D, anterior region, paratype 2♀; E, intestine and epidermal glands connected to setae, paratype 2♀.

Figure 6. Leptonemella brevipharynx sp. nov. A, anterior region, specimen 1 (indeterminate sex); B, head (frontal view), specimen 2 (indeterminate sex); C, head (lateral view), specimen 2 (indeterminate sex); D, mid-body with coccoid-shaped bacteria, specimen 1 (indeterminate sex); E, tail region with coccoid-shape bacteria, specimen 2 (indeterminate sex); F, spinneret aperture, specimen 2 (indeterminate sex).