Neochromadora parabilineata, Liang & Guo & Wang, 2024

Liang, Huixin, Guo, Wen & Wang, Chunming, 2024, Two new species of Hypodontolaiminae (Nematoda, Chromadorida, Chromadoridae) from the Yellow Sea with a phylogenetic analysis in the subfamily, ZooKeys 1190, pp. 281-302 : 281

Neochromadora parabilineata sp. nov.

Figs 3 , 4

Diagnosis.

Medium body size, buccal cavity with one large hollow dorsal tooth and two small subventral teeth, spicules curved and L-shaped, gubernaculum boat-shaped, seven precloacal supplements cup-shaped, tail conical and gradually tapering.

Material examined.

Four males and three females were measured and studied. Holotype: ♂ 1 on slide 22HSB11-2-20; paratypes: ♂ 2 on 22HSB11-1-21, ♂ 3 on 22HSB11-2-18, ♂ 4 on 22HSB11-2-20, ♀ 1 on 22HSB11-2-18, ♀ 2 on 22HSB11-1-18, and ♀ 3 on 22HSB11-2-18.

Type locality and habitat.

Rizhao coast, Shandong Province, China, 35°5′N, 119°20′E, 0-2 cm sediment depth, sandy sediment.

Measurements.

All measurement data are given in Table 4 .

Description.

Males. Body medium sized (864-943 μm), anterior end truncated and posterior end tapered. Cuticle heterogeneous and complex, five transverse rows of small dots present just posterior to cephalic setae, two or three longitudinal rows of larger dots posterior to the cephalic setae to middle part of body, larger dots changing to rectangular markings from middle body to posterior part of cloaca and rectangular markings changing back to larger dots until tail end. Six inner and six outer labial sensilla papilliform, four setiform cephalic sensilla (0.5-0.7 head diameter in length). Somatic setae present in pharynx and tail region (8 μm in length). Amphidial fovea situated at level of cephalic setae, transverse oval, 6-7 µm in width and 2 µm in length (50-58% corresponding body diameter). Buccal cavity shallow, 10-14 µm in depth. Cheilostoma short with cuticularized longitudinal folds. Pharyngostoma with one large hollow dorsal tooth and two small subventral teeth. Pharynx cylindrical, posterior region swollen into an oval bulb (17.5-17.7% of pharynx length). Nerve ring slightly posterior to middle pharynx region (64.2-66.9% of pharynx length). Secretory-excretory system present; renette cell situated posterior to pharynx bulb, excretory pore at level with cephalic setae. Cardia not observed.

Reproductive system with a single, outstretched testis. Spicules curved and L-shaped, widened at the middle part, 28-31 μm (0.81-0.86 cloacal body diameters) along arc. Gubernaculum short and boat-shaped, distal end tapered. Seven precloacal supplements cup-shaped, distance between the anteriormost and cloaca, the posteriormost and cloaca, 100 μm and 18 μm respectively, distance between supplements almost equal-distanced. Tail conical and gradually tapering, 4.4-4.8 cloacal body diameter in length. Spinneret short, 5 μm in length.

Females. Similar to males in most characteristics. Tail slightly longer than in males (5.8-6.8 anal body diameters in length). Reproductive system didelphic, with opposed and reflexed ovaries. Anterior ovary to left of intestine and posterior ovary to right of intestine. Spermatheca present. Vulva situated anterior to middle of body. Vagina short and muscularized.

Etymology.

Species epithet parabilineata refers to the new species being similar to Neochromadora bilineata .

Differential diagnosis.

Neochromadora parabilineata sp. nov. is similar to N. bilineata , N. izhorica , N. complexa , and N. poecilosoma in precloacal supplements number (7-9). But it differs from N. bilineata in body length (864-943 μm vs 567-852 μm), cephalic setae length (7-8 μm vs 4-6 μm), amphidial fovea width (50-58% vs 45% corresponding body diameter), spicules shape and length (L-shaped and widened in the middle portion, 28-31 μm vs arcuate and gradually narrowing, 23-26 μm), and gubernaculum length (19-22 μm vs 15-18 μm); differs from N. izhorica in cephalic seta length (7-8 μm vs 14 μm), pharynx shape (posterior bulb obvious vs posterior bulb weak), spicules length (28-31 μm vs 31.5-34.5 μm), gubernaculum shape (distal end tapered vs distal end with anterior-laterally curved tip) ( Riemann 1966); differs from N. complexa in body length (864-943 μm vs 642 μm), spicules shape (curved and L-shaped with middle portion widened vs L-shaped even in width), gubernaculum shape (boat-shaped vs dorsal part slenderly extended), distance between precloacal supplements (10-15 μm vs 2-5 μm) (calculation based on Gerlach 1953b: fig. 11); differs from N. poecilosoma in body length (864-943 μm vs 1900-2000 μm), cephalic setae length (7-8 μm vs 10-14 μm), spicule length (28-31 μm vs 60-65 μm), gubernaculum shape (boat-shaped vs distal tip with small tooth) ( de Man 1893).

Figures

Figure 3. Neochromadora parabilineata sp. nov. A lateral view of male anterior region showing cuticle and amphidial fovea (holotype) B lateral view of male buccal cavity (holotype) C lateral view of male anterior region showing pharyngeal region (holotype) D lateral view of male cuticle at pharynx region (holotype) E lateral view of male cuticle at middle body (holotype) F lateral view of female anterior region showing buccal cavity and pharyngeal region (22 HSB 11 - 1 - 18) G lateral view of spicules and gubernaculum (22 HSB 11 - 2 - 20) H lateral view of male posterior body, showing precloacal supplements and tail (holotype) I lateral view of female whole body (22 HSB 11 - 2 - 18) J lateral view of female posterior body showing tail (22 HSB 11 - 2 - 18). Scale bars: 20 µm (A-H, J); 50 µm (I).

Figure 4. Neochromadora parabilineata sp. nov. A lateral view of male anterior region showing cuticle (holotype) B lateral view of female anterior region showing amphidial fovea (arrow) (22 HSB 11 - 2 - 18) C lateral view of cuticle at middle body (holotype) D lateral view of male posterior body, showing spicules (22 HSB 11 - 2 - 20) E lateral view of male posterior body, showing gubernaculum (22 HSB 11 - 2 - 20; F lateral view of male posterior body, showing precloacal supplements (arrows) (holotype) G lateral view of male posterior body, showing tail and cuticle (22 HSB 11 - 2 - 20). Scale bars: 20 µm.