Stegelleta waltrautae, Mach & Pettrich & Villegas & Waldvogel & Schiffer & Holovachov, 2025

Mach, Niclas, Pettrich, Laura, Villegas, Laura, Waldvogel, Ann-Marie, Schiffer, Philipp H. & Holovachov, Oleksandr, 2025, Description of Cervidellus hueckeswagensis sp. nov. and Stegelleta waltrautae sp. nov. (Nematoda: Rhabditida: Cephalobidae) from the Atacama Desert in Chile, European Journal of Taxonomy 1012, pp. 222-238 : 230-233

Stegelleta waltrautae sp. nov.

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Figs 4–6 , 7G–H , Tables 3–4

Diagnosis

Stegelleta waltrautae sp. nov. is characterized by a body length of 531–631µm in females and 576– 583 µm in males; cuticle divided by longitudinal incisures into about 30 irregular ridges; lateral alae with five incisures extending to tail terminus; three pairs of asymmetrical lips, pairs of lips separated by U-shaped primary axils without guarding processes, and asymmetrically trapezoidal lips with two elongate-triangular tines along margin: one longer tine facing the primary axil and one shorter tine facing secondary axil; three labial probolae each bifurcated at about half of their length; prongs slender, apically curved towards each other, without secondary tines or bifurcations; pharyngeal corpus 3.1–4.7 × as long as isthmus; nerve ring and excretory pore at isthmus / basal bulb level; vulva convex with less thickened anterior vulval lip and more thickened posterior vulval lip; spermatheca 28.0–36.0 µm long; and post-vulval uterine sac 25.0–39.0 µm long.

Etymology

The new species is named in honor of the first author’s grandmother, who recently passed away.

Type material

Holotype

CHILE • ♀; Atacama Region, Copiapo Province, Totoral ; 27°47.633′ S, 71°02.867′ W; 189 m a.s.l.; 3 Oct. 2023; O. Holovachov and P. Schiffer leg.; dune area, soil under a cactus, sample code TDT.23.14 ( Fig. 7G–H ); SMNH Type-9946; SMNH.

Paratypes

CHILE • 4 ♀♀, 2 ♂♂; same collection data as for holotype; SMNH Type-9946; SMNH .

Description

Adult

Body straight or slightly curved ventrad upon fixation (fixed without applying heat). Cuticle coarsely annulated, annuli 2.5–3.0 µm wide at midbody. Distinct longitudinal incisures present, giving cuticle tiled appearance, cuticular blocks with rounded corners, arranged in about 30 irregular longitudinal ridges (in addition to lateral alae). Lateral alae start with three incisures at level of metacorpus and expands to five incisures at level with deirid, extending to tail terminus in both sexes. Lip region continuous, with six labial and four cephalic papillae. Amphid opening relatively small, oval, located at the base of each lateral lip. Three pairs of asymmetrical lips, one dorsal and two ventrolateral. Pairs of lips separated by U-shaped primary axils without guarding processes. Secondary axils U- or V-shaped without guarding processes. Each lip asymmetrically trapezoidal with two elongate-triangular tines along margin: one longer tine facing primary axil and one shorter tine facing secondary axil. Three labial probolae, bifurcated at about half of their length; prongs slender, apically curved towards each other, without secondary tines or bifurcations. Longitudinal swellings or ridges absent. Stoma slightly longer than lip region diameter. Cheilorhabdia bacilliform in latero-median view; metastegostom with small dorsal denticle. Pharynx cephaloboid. Pharyngeal corpus cylindrical; isthmus less well demarcated from corpus; basal bulb oval with well-developed grinder. Nerve ring surrounding isthmus. Excretory pore at level of isthmus-bulb junction. Deirids at level with basal bulb.

Female

Reproductive system monodelphic, prodelphic, in dextral position relative to intestine. Ovary reflexed posteriorly at oviduct, straight or with two flexures posterior to vulva. Vulval region convex, well pronounced with less thickened anterior vulval lip and more thickened posterior vulval lip. Spermatheca well developed. Post-vulval uterine sac usually small, about equal to one vulval body diameter. Tail conoid with 14–15 ventral annuli, and rounded tip. Phasmids located at about 32–42% of tail length.

Male

Reproductive system monorchic, dextral in position; testis usually reflexed ventrad anteriorly. Spicules paired and symmetrical, curved ventrad; with oval manubrium and subcylindrical, gradually narrowing shaft. Gubernaculum curved plate. Genital papillae distributed as follows: two pairs of subventral precloacal papillae (33–35 µm and 79–80 µm from cloacal aperture, respectively) and one subventral pair at level of cloacal aperture; single midventral papilla on anterior cloacal lip; one caudal pair subventrally few annuli posterior to cloacal aperture, second caudal pair laterally at mid-tail very close to the phasmids and three more pairs (one subdorsal, one subventral and one lateral) near tail terminus. Phasmids located at about 33–40% of tail length. Tail conoid with short bluntly rounded mucro.

Differential diagnosis

Stegelleta waltrautae sp. nov. from Chile is most similar to S. tuarua Yeates, 1967 in having a large number of longitudinal lines (rows of cuticular blocks) and in having lateral alae (filed) with five incisures, thus differing from the remaining six species of the genus ( Table 4 ; Boström & Holovachov 2014). The new species, however, differs from S. tuarua in the shape of the cephalic probolae (with two acute tines vs single tine in S. tuarua ) and distinctly protruding vulva (vs continuous with body contour).

Figures

Fig. 4. Stegelleta waltrautae sp. nov. A–C. Holotype, ♀ (SMNH Type-9946). A. Pharyngeal region. B. Reproductive system. C. Caudal region. D. Paratype, ♂ (SMNH Type-9946), caudal region. E. Paratype, ♀ (SMNH Type-9946), entire specimen. F–G. Schematic illustration of the details of the head region, combined based on several individual nematodes. F. Anterior end, surface view. G. Cephalic and labial probolae.

Fig. 5. Stegelleta waltrautae sp. nov. A–B, D, F, H. Female paratypes (SMNH Type-9946). C, E. Holotype, ♀ (SMNH Type-9946). G, I–J. Male paratypes (SMNH Type-9946). A. Anterior pharyngeal region. B, H. Spermatheca. C. Vulva with post-vulval uterine sac. D. Post-vulval uterine sac. E. Caudal region. F–G. Posterior pharyngeal region (arrow points at excretory pore). I. Caudal region (arrow points at lateral papilla). J. Testis. Scale bars = 20 μm.

Fig. 6. Stegelleta waltrautae sp. nov. A. Holotype, ♀ (SMNH Type-9946). B. Paratype, ♂ (SMNH Type-9946). C–F. Female paratypes (SMNH Type-9946). A–F. Anterior end, views from different sides (arrows show papillae). Scale bar = 10 µm.

Fig. 7. Habitats. A–F. Sampling sites of Cervidellus hueckeswagensis sp. nov. A–B. ALT.22.0. C–D. EPT.22.3830. E–F. ALT.22.08. G–H. Sampling site of Stegelleta waltrautae sp. nov., TDT.23.14.