Ceramonema taiora, Leduc, 2024

Leduc, Daniel, 2024, Four new free-living marine nematode species (Plectida: Ceramonematidae) and two new species records (Desmodorida: Desmodorinae) from Rangitāhua / Kermadec Islands, Aotearoa / New Zealand, European Journal of Taxonomy 970, pp. 138-174 : 151-153

Ceramonema taiora sp. nov.

urn:lsid:zoobank.org:act:90D8C255-78AD-4C9B-BA3A-7996D252B103

Figs 5–6 , Table 1

Diagnosis

Ceramonema taiora sp. nov. characterised by body length 1040–1141 µm, relatively small number (119–127) of body annules, cuticle with conspicuous zygapophyses, presence of intracuticular vacuoles, cephalic setae 0.29–0.38 cbd long, relatively large loop-shaped amphids that are slightly smaller in females than in males, wide cloacal annule formed by fusion of two contiguous annules, presence of conspicuous precloacal spine, and gubernaculum with small rounded apophyses.

Differential diagnosis

The new species belongs to Group 1 (species with distinct zygapophyses) and is similar to Ceramonema taikoraha sp. nov., C. salsicum (described from the Bay of Biscay, NE Atlantic), and C. africana (described from the coast of South Africa) in having cuticle ornamentation with distinct zygapophyses, body length greater than 700 µm, ratio of a ≤ 70, cephalic setae ca ⅓ of cephalic capsule length or less, and cephalic capsule with intracuticular vacuolisation.

Ceramonema taiora sp. nov. differs from C. taikoraha sp. nov. by shorter body length (1040–1141 vs 1380–1428 µm in C. taikoraha sp. nov.), lower ratio of a (32–36 vs 49–60 in C. taikoraha sp. nov.), lower ratios of b and c (4–6 vs 7–8 in C. taikoraha sp. nov.), lower number of body annules (119–127 vs 161–177 in C. taikoraha sp. nov.), cloacal annule morphology (fused annules vs two unfused contiguous body annules in C. taikohara sp. nov.), longer amphids (19–26 vs 16–18 µm in C. taikoraha sp. nov.), and presence of precloacal spine (vs absent in C. taikoraha sp. nov.).

The new species differs from C. salsicum by greater body length (1040–1141 vs 960 µm in C. salsicum ), lower ratio of a (32–36 vs 38 in C. salsicum ), lower number of body annules (119–127 vs 145 in C. salsicum ), shorter tail (8–9 vs 10 cloacal body diameters long in C. salsicum ) and presence of a precloacal spine (vs absent in C. salsicum ); from C. africana in lower ratio of a (32–36 vs 35–49 in C. africana ), lower number of body annules (119–127 vs 156–170 in C. africana ), longer amphids (in males: 23–26 vs 10–15 µm in C. africana ; in females: 19–20 vs 9 µm in C. africana ), longer cephalic capsule (37–45 vs 27–33 in C. africana ), and presence of a precloacal spine (vs absent in C. africana ).

Ceramonema taiora sp. nov. is also similar to C. inguinispina (described from the Gulf of California) in having body length greater than 700 µm, ratio of a ≤ 70, cephalic setae ca ⅓ of cephalic capsule length or less, cephalic capsule with intracuticular vacuolisation and presence of precloacal spine, but differ in cuticle ornamentation (distinct vs small zygapophyses in C. inguinispina ), lower number of body annules (119–127 vs 135–191 in C. inguinispina ), longer amphids (19–26 vs 6–14 µm in C. inguinispina ) and longer spicules (27–28 vs 20–26 µm in C. inguinispina ).

Etymology

‘ Tairoa ’ are nutrients ingested by nematode worms (‘ toke ’). Active nematode populations help cycle nutrients at the seabed thus helping to maintain healthy ocean (‘ moana ’) ecosystems. Māori name ‘ toke tairoa ’.

Type material

Holotype NEW ZEALAND • ♂; Kermadec Islands , Raoul Island (off Western Spring); 29.22992° S, 177.96448° W; depth 16 m; 22 Nov. 2021; coarse sand and gravel sediments, voyage TMOR2021 , station 85; NIWA 154945 .

Paratypes NEW ZEALAND • 1 ♂, 4 ♀♀; same data as for holotype; NIWA 154946 .

Type habitat and locality

Shallow subtidal, Raoul Island, New Zealand.

Description

Male

Body almost colourless, with slight golden colouration, cylindrical, slightly wider in pharyngeal region than in mid- and posterior body region and tapering slightly towards posterior extremity. Cuticle coarsely annulated along entire body, except for smooth cephalic capsule and terminal cone. Each annule divided into plates by eight longitudinal crests /ridges extending from cephalic capsule to terminal cone. Epicristae of each annule slightly overlapping adjacent annules. Zygapophyses conspicuous. Annules unequal in width and often wider dorsally than ventrally; annule width increasing gradually from first postcephalic annule (10–12 µm, as measured in lateral field) to annule number 22–27 or slightly posterior to ventral gland (ca 16 µm), followed by a much narrower one (10–11 µm); annules then widen slightly (11–14 µm), and stay roughly equal in size for all of mid-body region until immediately cloacal annule; cloacal annule ca 25–27 µm wide, made of two fused contiguous annules and with suture mostly visible ventrally; this annule followed posteriorly by 15 µm wide annule then by caudal annules gradually decreasing in width toward terminal cone; last annule before terminal cone is narrowest (5 µm). Intracuticular vacuoles occurring within posterior part of cephalic capsule and within body annules. Cuticle pores not observed. Lateral alae absent. Cephalic capsule elongated, slightly longer than wide, cylindrical with rounded lip region not set off by any constriction although fine suture visible on cuticle surface below insertion point of outer labial sensilla. Longitudinal crests extending from base of cephalic capsule to about level of base of anterior edge of amphids. Inner labial sensilla not observed. Outer labial setiform, located anterior to, and slightly longer than, cephalic setae (0.37 cbd long). Loop-shaped amphids located in posterior and middle of cephalic capsule; amphidial aperture slightly shorter than amphidial fovea. Buccal cavity small, funnel shaped, without differentiation. Pharynx cylindrical, subdivided into anterior corpus and posterior postcorpus; corpus ca 60–65% of pharynx length, cylindrical, narrowing slightly posteriorly, muscular; postcorpus ca 35–40% of pharynx length, also muscular consisting of short, anterior narrow isthmus and pear-shaped basal swelling. Pharyngeal glands indistinct. Pharyngeal lumen uniform in thickness, tubes and valve-like structures absent. Cardia 5–8 µm long, surrounded by intestine. Nerve ring surrounding anterior portion of isthmus. Secretory-excretory system present; excretory pore on annule 17–18; ventral gland slightly posterior to cardia.

Reproductive system diorchic, anterior testis outstretched and located to right of intestine, posterior one located to left of intestine; position, and structure of posterior testis relative to intestine could not be determined. Spicules paired, symmetrical, weakly arcuate with bent proximal portion. Gubernaculum plate-like with small, rounded dorsocaudal apophyses. Conspicuous precloacal spine present. Ten pairs of subventral caudal setae, 8–10 µm long. Caudal glands not observed. Terminal cone 19–27 µm long.

Female

Similar to males, but with shorter and narrower amphidial fovea and longer tail without caudal setae. Cephalic setae 0.27–0.38 cbd long. Reproductive system didelphic, amphidelphic, with reflexed ovaries; anterior ovary to right of intestine and posterior ovary on left of intestine. Vulva a transverse slit located slightly anterior to mid-body.Vagina straight, with thickened walls. Pars refringens vaginae not observed. Intrauterine egg not seen. Anal annule similar to adjacent annules.

Figures

Fig. 5. Ceramonema taiora sp. nov. A–B, G. Holotype, ♂ (NIWA 154945). C–F, H–I. Paratypes (NIWA 154946). A. Cephalic region, surface view. B. Cephalic region, optical cross-section view.C. ♂, cephalic region, combined (super-imposed) surface and cross-scetion views. D. ♀, cephalic region, view. E. ♂, cloacal region. F. ♂, posterior body region. G. Pharyngeal body region. H. ♀, reproductive system. I. ♀, posterior body region. Scale bar: A–D = 30 µm; E = 16 µm; F = 33 µm; G, I = 45 µm; H = 68 µm.

Fig. 6. Ceramonema taiora sp. nov., paratypes (NIWA 154946), light micrographs. A. ♂, surface view of cephalic region. B. ♂, optical section of cephalic region. C. ♂, surface view of cuticle, mid-body region. D. ♂, cloacal region, showing specular apparatus and precloacal spine. E. ♂, surface view of cloacal region. F. Entire female. Scale bar: A–E = 20 µm; F = 85 µm.