Cervonema multispira, Leduc, 2012

Leduc, Daniel, 2012, Deep-sea nematodes (Comesomatidae) from the Southwest Pacific Ocean: five new species and three new species records, European Journal of Taxonomy 24, pp. 1-42 : 11-13

Cervonema multispira sp. nov.

urn:lsid:zoobank.org:act:D4A82AED-213B-4CE4-9D62-FAAC2D44CBC0

Figs 5-6 , Table 2

Etymology

The species name is derived from the Latin multus (= much) and spiralis (= coil), and refers to the shape of the amphid.

Material examined

Holotype

Ƌ, collected 6Apr. 2007, southern flank of Chatham Rise (1240 m water depth), 44.4864°S, 177.1407°E. Characteristics of surface sediment layer (0-5 mm): mostly silt/clay (82.9%), with very fine sand (10.2%), and fine sand (8.4%); calcium carbonate content: 38.4%; total organic matter content: 1.9%; chloroplastic pigment concentration: 3501 ng /gDW sediment (NIC 84444).

Paratypes

1 Ƌ, 2 ♀♀, same data as holotype (NIC 84445).

Description

Males

Body cylindrical, tapering towards both extremities, orange-brown colouration throughout. Cuticle faintly striated, no lateral differentiation. Somatic setae short and sparse. Head set-off by a depression at level of cephalic setae. Inner labial papillae indistinct, six outer labial setae, and four slightly shorter cephalic setae, the latter two in separate circles. Amphideal fovea spiral, 8.0-8.5 turns, situated 2.6- 4.0 head diameters from anterior. Small buccal cavity, cup-shaped. Pharynx with small posterior bulb. Cardia short. Nerve ring near 60% of pharynx length from anterior. Secretory-excretory pore slightly posterior to nerve ring. Cellular body of ventral gland small, posterior to cardia. Six large uninucleated pseudocoelomocytes, 23 μm wide, 35-40 μm long, in anterior half of body, with 2 and 4 cells on either side of intestine in holotype, 3 cells on either side of intestine in paratype, each with single extension (or possibly duct) directed anteriorly ( Fig. 6A ). Intestine wall consisting mostly of cells containing small granules, interspersed with clusters of clear globular inclusions

Reproductive system diorchic, opposed, outstretched. Anterior testis to left of intestine, posterior testis to right of intestine. Sperm cells small (up to 5×4 μm), globular, with lenticular nuclei situated peripherally. Spicules paired, equal, arcuate, 0.9-1.1 abd long, strongly cuticularised along entire length, with capitulum. Four pairs of small ejaculatory glands situated anteriorly to spicules ( Fig. 5C ). Small rectal gland present. Gubernaculum not observed. Five small, tubular pre-cloacal supplements, one precloacal seta. Tail conico-cylindrical, with several short caudal setae and three short terminal setae. Three caudal glands and spinneret present.

Females

Similar to males, but with smaller amphideal fovea, 7.5 turns. Large nucleated cells in anterior part of body not observed. Reproductive system didelphic, opposed, outstretched, with anterior branch to left of intestine and posterior branch to right of intestine. Spermatheca present, containing sperm. Vulva slightly post median. Granular vaginal glands present, pars proximalis vaginae surrounded by constrictor muscle.

Diagnosis and relationships

Cervonema multispira sp. nov. is characterised by body length 1225-1431 μm, amphideal fovea with 8.0-8.5 turns, 2.6-4.0 head diameter from anterior end, cephalic setae 2-3 μm long, slightly shorter than outer labial setae, presence of six large lateral cells in males only, 5 small pre-cloacal supplements, strongly cuticularised, arcuate spicules with capitulum, and tail 4.4-6.1 abd.

Cervonema multispira sp. nov. resembles C. macramphis Jensen, 1979 in body size, length of cephalic setae, amphid with numerous (> 7) turns, and the presence of arcuate spicules. Cervonema multispira sp. nov. can be differentiated from C. macramphis and all other species of the genus by amphideal fovea with 8.0-8.5 turns (<7.5 turns in all other species), presence of lateral excretory cells in males, and strongly cuticularised spicules with capitulum. C. multipsira sp. nov. also resembles C. pseudodeltensis Barnes et al., 2012 in having outer labial setae marginally longer than cephalic setae, but is characterised by shorter body length (1225-1431 vs. 1559-1755 μm), amphideal fovea with more turns (8.0-8.5 vs. 5.5) and absence of gubernaculum (present in C. pseudodeltensis ).

Discussion

To my knowledge, this is the first time that the presence of large uninucleated cells is noted in the pseudocoelom of Cervonema specimens. Similar cells, usually situated laterally, and sometimes subventrally, have been described in Sabatieria celtica Southern, 1914 ( Riemann 1977), S. pulchra (Schneider, 1906) ( Jensen 1979) , S. breviseta Stekhoven, 1935 , and S. punctata (Kreis, 1924) ( Platt 1984) . Only two cells (described as supplementary excretory cells) are found in Sabatieria spp., whereas six were observed in Cervonema multispira sp. nov. This type of cell has not been observed in females of Sabatieria spp. or C. multispira sp. nov.

Figures

Fig. 5. Cervonema multispira sp. nov. A. Ƌ anterior body region. B. ♀ head. C. Ƌ posterior body region, showing copulatory apparatus. D. ♀ intestine. E. ♀ tail. Arrows point to the four ejaculatory glands. Scale bar: A =30 μm; B = 20 μm; C = 40 μm; D = 28 μm; E = 25 μm.

Fig. 6. Cervonema multispira sp. nov. A. Entire Ƌ. B. ♀ reproductive system. Scale bar: A =100 μm; B = 70 μm.