Desmicola lamdongensis, Sokolova, 2019

Sokolova, Elena A., 2019, Desmicola lamdongensis sp. n. (Oxyuridomorpha: Thelastomatidae) from Vietnamese wood-burrowing cockroaches (Panesthiinae), Zootaxa 4679 (1), pp. 87-96 : 88-92

Desmicola lamdongensis sp. n.

( Figs. 1–3 )

Morphometric data: Table 1 .

Adult specimens are distinguished by remarkable sexual dimorphism.

Male: Body C-shaped, when fixed. Cuticle prominently annulated throughout whole body length. Head capsule thimble-shaped, 68–80×65–73 (70×65) µm. Mouth opening surrounded by small lips bearing four submedian fused pairs of labial papillae and two slit-like amphids, with approximate width of apertures 3–4 µm. Lateral alae beginning at 4 th annulus, just posterior to head capsule, and ending nearly in front of cloaca. Posterior third of body having seven, sometimes eight, modified ventrally projected cuticular annuli. Diameter of the first annulus 78–98 (88) µm, the second—83–103 (93) µm, the third—88–103 (95) µm, the fourth—90–103 (95) µm, the fifth—90–100 (95) µm, the sixth—85–98 (93) µm and the seventh—78–95 (88) µm. Tail subulate.

Stoma small, funnel-shaped, with thickened cuticularized walls, ca. 6–7 µm in height and 4–5 µm in diameter. Pharynx long, occupying anterior third of body. Pharyngeal corpus spindle-shaped, 240–260 (270) µm long and 18–25 (20) µm wide, isthmus thin-walled, indistinct, and basal bulb 40–48 (40) µm in diameter. Cardia small. Anterior part of intestine slightly broadened, 40–68 (48) µm in diameter.

Nerve ring 175–200 (195) µm from anterior end, at average 75% (72%) of pharyngeal corpus length.

Excretory pore slightly posterior to corpus-isthmus junction, between 18 th and 19 th cuticular annuli.

Monorchic. Testis flexure at 375–440 (420) µm from anterior end. Spicule with distinct capitulum, straight, thickened at mid-length and terminating in pointed distal tip. Gubernaculum poorly visible.

Four pairs of genital papillae present: a pair of prominent conical, 8–10 µm high, sub-ventral pre-cloacal papillae, a pair of lateral adcloacal papillae, a pair of small papillae placed posterior to spicule on protruding post-cloacal lip, and a pair of protruding papillae, situated dorsally in 73–95 µm from tail terminus on caudal filament.

Phasmids located between cloacal opening and the fourth pair of papillae.

Female: Semispherical head capsule attached to long fusiform body ending in long filament. Cuticle thick, with prominent annulation. Head capsule 53–58 µm in diameter and 35–38 µm in height, lip region surrounded by fine rim. Three fused lips covered by fine transparent membrane. Mouth opening triangular, with shallow bifurcation at each side of triangle: dorsal lip bilobed, sub-ventral lips trilobed. Lip surface covered by tiny circular protrusions. Dorsal lip bearing two separate papillae, each sub-ventral lip with two fused papillae and one amphid in the shape of a horseshoe. Three single setiform sensilla situated between mouth corners. Lateral alae extending from the level of pharyngeal corpus end to anus.

Stoma of complex structure, pear-shaped, with strongly cuticularized walls, ca. 25–27 µm long and 14–15 µm wide. One dorsal and two sub-ventral cuticular plates in stoma, each with 11–12 longitudinal striae terminating anteriorly by fine tooth-like formations. Pharyngeal corpus cylindrical, 230–278× 20–25 µm, isthmus thin-walled, and basal bulb 50–70 µm in diameter. Cardia prominent, projecting into intestinal lumen. Proventriculus 65–100 µm in diameter. Rectum surrounded by three elongated rectal cells with distinct rounded nuclei. Anal opening situated just behind last cuticular annulus.

Nerve ring in 128–155 µm from anterior end, at about 60% of pharyngeal corpus length.

Excretory pore with strongly cuticularized duct and opening, at level of corpus-isthmus junction. Excretory vesicle large, 40–50× 25–30 µm, filled with granular brownish content.

Didelphic, amphidelphic, both ovaries reflexed. Posterior branch bearing a seminal receptacle. Vagina with thick muscular wall, directed anteriorly. Vulva opening situated in 150–225 µm (12–14 cuticular annuli) anterior to anus.

Four to ten eggs in uteri, 88–98× 53–65 µm, with thick, smooth egg-shells.

Type material. Holotype male (accession No. 1188), 13 paratype males (accession nos. for five individual specimens 1196–1200), and 7 paratype females (accession no. for one specimen 1201) are deposited in the Museum of Helminthological Collections at the Center of Parasitology , A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, Moscow, Russia.

Type locality. Bi Doup-Nui Ba National Park , Lam Dong province, Vietnam. Cockroaches were collected by Dr. Sergei Spiridonov in June 2007 .

Type host. Panesthia sp. (Dictyoptera: Blattaria: Blaberidae )

Type species. Desmicola leidyi ( Skrjabin, 1916) Basir, 1956 ; British East Africa

Diagnosis. Desmicola , Thelastomatidae, Thelastomatoidea, Oxyuridomorpha (after Basir 1956; Hugot et al. 1991; Adamson & Van Waerebeke 1992; emended). Adult specimens of both sexes have prominently annulated body cuticle with distinct lateral alae and inflated cephalic extremities. Nerve ring at posterior half of pharyngeal corpus. Excretory pore near level of pharyngeal bulb. Tail terminus filiform. Males with long, spindle-shaped pharyngeal corpus. Posterior third of body with a region of modified cuticular surface. Spicule single. Four pairs of genital papillae present (a pair of sub-ventral pre-cloacal papillae, a pair of lateral adcloacal papillae, a pair of papillae placed posterior to spicule on protruding post-cloacal lip, and a pair of papillae situated dorsally on caudal filament). Females with three lobe-shaped lips; lip surface ornamented differently; interlabial formations absent or present. Stoma cuticularized, with one dorsal and two sub-ventral cuticular plates having longitudinal striae terminated anteriorly by tiny tooth-like formations. Pharyngeal corpus cylindrical. Didelphic, amphidelphic. Posterior branch bearing a seminal receptacle. Vulva just anterior to anus. Eggs broadly oval.

Figures

FIGURE 1. Desmicola lamdongensis sp. n. (Oxyuridomorpha: Thelastomatidae) A–C—male, D–H—female.A—anterior end, pharynx; B—modified ventrally projected cuticular annuli; C—posterior end showing reproductive system, arrangement of genital papillae with spicule and position of ventrally projected cuticular annuli; D—anterior end, pharynx; E—head capsule, stoma; F—head capsule, stoma, superficial en face view; G—stoma showing longitudinal striae in cross section; H—reproductive system. A–E in lateral view. Scale bars: A–D & H=50 µm, E–G=20 µm.

FIGURE 2. Desmicola lamdongensis sp. n. (Oxyuridomorpha: Thelastomatidae)—male (SEM & LM). A—habitus; B—head capsule, stoma, superficial en face view; C—posterior end; D—modified ventrally projected cuticular annuli; E—spicule; Ftail region with arrangement of genital papillae. Except B, all in lateral view. Abbreviations: amph—amphids (arrows), P1—a pair of sub-ventral pre-cloacal papillae, P2—a pair of lateral adcloacal papillae, P3—a pair of papillae placed posterior to spicule on protruding post-cloacal lip, P4—a pair of protruding papillae situated on caudal filament, ph—phasmid. Scale bars: A=100 µm, B & F=10 µm, C & D=30 µm, E=20 µm.

FIGURE 3. Desmicola lamdongensis sp. n. (Oxyuridomorpha: Thelastomatidae)—female (SEM & LM).A—habitus; B—head capsule, ventral view; C—head capsule, stoma, superficial en face view; D—excretory pore; E—vulval region and seminal receptacle. A, D & E in lateral view. Scale bars: A=200 µm; B & C=10 µm, D & E=20 µm.