Gammanema agglutinans, Leduc, 2013

Leduc, Daniel, 2013, Two new genera and five new species of Selachinematidae (Nematoda, Chromadorida) from the continental slope of New Zealand, European Journal of Taxonomy 63, pp. 1-32 : 21-25

Gammanema agglutinans sp. nov.

Figs 11-13 , Table 2

urn:lsid:zoobank.org:act:3AEBAD01-7722-489F-B9FF-818C5B1B8617

Diagnosis

Gammanema agglutinans sp. nov. is characterised by short, stout body (a = 10-15), cuticle with minute spines, leaf-shaped somatic setae with ducts, sexual dimorphism in the shape of the amphideal fovea (loop-shaped in males and spiral in females), posterior buccal cavity with three pairs of broad, columnshaped rhabdions fused anteriorly, intestine cells conspicuous with orange-brown granules, slightly curved spicules, 0.8-1.0 abd long, and small tubular pre-cloacal supplements.

Etymology

The species name is derived from the Latin word glutino (= glue, paste together) and refers to the mucus and debris adhering to cuticle of this species.

Material examined

Holotype

NEW ZEALAND: ♂, NIWA 88362 , 20 Feb. 2011, NIWA cruise TAN1103, station 69, central Chatham Rise , 43.331° S, 178.288° E, 350 m, sediment depth 1-5 cm, mean grain size 55-59 μm, 55-57% sand, particle sorting (geometric) 4.1-4.3.

Paratypes

NEW ZEALAND: 1 ♂, 1 ♀, NIWA 88363, same data as holotype. 1 ♀ NIWA 88364, 6 Apr. 2007, NIWA cruise TAN0705, station 45, southern flank of Chatham Rise, 44.4864° S, 177.1407° E, 1238 m, silt/clay (93.9%).

Description

Males

Body short, stout, cylindrical, tapering slightly towards anterior extremity, covered with thin layer of adhering mucus and small detrital particles. Cuticle ~ 1.0-1.5 μm thick, with transverse rows of punctations, without lateral differentiation, each punctation terminating into a minute spine (spines often difficult to observe due to presence of adhering particles). Four sub-lateral rows of leaf-shaped somatic setae (i.e., with narrow base, wide middle portion, and tapering distal end), each with a central duct, 4-8 μm long and 2 μm wide ( Fig. 13E ). Head blunt, only slightly rounded, not set off. Mouth opening surrounded by six pairs of thin, leaf-shaped cuticle extensions, 3-4 μm long ( Fig. 11A, B ). Labial sensillae in three separate circles; inner and outer labial setae conical, ~ 2 μm long, each with central duct; four cephalic setae, each with central duct, <0.3 cbd. Loop-shaped amphideal fovea, situated <0.2 cbd from anterior extremity. Buccal cavity divided into anterior and posterior portions; anterior portion of buccal cavity large, funnel-shaped, with twelve cuticularised rhabdions, each with one pair of pointed projections at posterior extremity ( Fig. 13D ). Posterior buccal cavity narrow, cylindrical, surrounded by three pairs of broad, column-shaped rhabdions fused in anterior half ( Fig. 13B ). Pharynx without anterior bulb; pharynx widens posteriorly but not forming true posterior bulb. Nerve ring at ~ 40% of

pharynx length from anterior. Secretory-excretory (S-E) system not observed. Intestine cells large, well- defined, with numerous round, orange-brown inclusions ( Fig. 13A ).

Reproductive system diorchic with short, outsretched testes. Testes situated either both ventrally or with anterior testis on left of intestine and posterior testis on right of intestine; small, globular to oval-shaped sperm cells, 2-4 × 5 μm. Spicules paired, 0.8-1.0 abd long, slightly curved, with slight constriction near proximal extremity and tapering distally. Gubernaculum small, slightly bent at proximal end, with lateral pieces (crurae) flanking the distal end of the spicules and a small cuneus with two small, drop-shaped projections anteriorly (not visible in paratype male). At least six small tubular pre-cloacal supplements, difficult to observe due to adhering particles; pre-cloacal seta present. Tail short, conical, with few sparse sub-dorsal setae. Three caudal glands and spinneret present.

Females

Similar to male, but with conspicuously smaller spiral amphideal fovea, 1.5 turns. Reproductive system didelphic-amphidelphic, with reflected ovaries. Anterior ovary on left of intestine, posterior ovary on right of intestine. Vulva located at two thirds of body length from anterior extremity. Pars proximalis vaginae surrounded by constrictor muscle, vaginal glands not observed.

Remarks

G. agglutinans sp. nov. differs from all other species in the genus in having a cuticle with spines (vs. spines absent in all other species), males with loop-shaped amphids (vs. multispiral amphids) and leafshaped somatic setae with ducts (vs. slender setae without ducts). In addition, species of the genus are characterised by either cup-shaped or setose pre-cloacal supplements, whereas G. agglutinans sp. nov. is characterised by tubular supplements.

Figures

Fig. 11. Gammanema agglutinans sp. nov. A. Surface view of female head. B. Surface view of male head. C. Female head, showing buccal cavity. D. Female head, showing buccal cavity. E. Entire male. F. Spicule and gubernaculum. Scale bar: A-D = 30 μm; E = 40 μm; F = 18 μm.

Fig. 12. Gammanema agglutinans sp. nov. A. Entire female. B. Entire male. Scale bar: A = 60 μm; B = 50 μm.

Fig. 13. Gammanema agglutinans sp. nov. Light micrographs. A. Entire male. B. Buccal cavity of female, showing paired rhabdions in posterior buccal cavity. C. Posterior region of pharynx, cardia, and anterior region of intestine of female. D. Buccal cavity of female, showing pointed projections at posterior extremity of rhabdions in anterior buccal cavity. E. Cuticle of male, showing punctations, spines, and somatic setae. Scale bar A = 30 μm; B, D = 15 μm; C = 12 μm; E = 7 μm.