Acanthopharynx denticulatus Wieser, 1954

Armenteros, Maickel, Ruiz-Abierno, Alexei & Decraemer, Wilfrida, 2014, Revision of Desmodorinae and Spiriniinae (Nematoda: Desmodoridae) with redescription of eight known species, European Journal of Taxonomy 96, pp. 1-32 : 5-7

Acanthopharynx denticulatus Wieser, 1954

Figs 1A–D , 2 , Table 1

Acanthopharynx denticulatus Wieser, 1954: 36 .

Material examined

10 ♂♂, 10 ♀♀ and 10 juveniles, deposited in the nematode collection at Centro de Investigaciones Marinas, Universidad de La Habana, CUBA.

Description

Cuticle strongly striated in the anterior part (annuli width ~ 1 μm) becoming finer at mid-body. Head capsule well developed. Six inner and six outer labial setae, both sets papilliform. Four cephalic setiform sensilla 4–8 μm long. Two circles of 10–12 subcephalic setae, 6–8 μm long and very close to each other. One pair of sublateral setae 4–6 μm long at level of amphidial fovea. Amphidial fovea cryptospiral located in the head capsule and not surrounded by cuticle striations. Eight longitudinal rows of short somatic setae (<5 μm) running along the anterior body region, continuing as six longitudinal rows at mid-body and four rows on the tail. Buccal cavity with 12 cheilorhabdia, one large dorsal tooth and two smaller ventrosublateral teeth, a transverse row of 7–10 minute denticles at level of tip dorsal tooth. Pharynx meandering with posterior widened bulb marked by several plasmatic interruptions, internal lining well sclerotized. Cardia not conspicuous. Secretory-excretory system not observable. End portion of tail smooth, showing a characteristic ventral bend; spinneret well developed.

Male monorchic, the anterior testis to the right of the intestine. Spicules strongly bent, with capitulum, gubernaculum a straight rod oriented dorsally. Precloacal ventromedian supplements (13–16) visible as small pits located on a cuticular ridge.

Female didelphic, ovaries antidromously reflexed, anterior genital branch to the right of the intestine, posterior genital branch to the left.

Juveniles are similar to adults except for the development of the reproductive system.

Remarks

At present, the genus Acanthopharynx Marion, 1870 includes 11 valid species. A dichotomous key to eight of the species was published by Wieser (1954). At least two species, A. brachycapitata Allgén, 1947 ( Allgén 1947: 148) and A. similis Allgén, 1932 , have to be regarded as species inquirendae due to their poor description. The differences among the Acanthopharynx species are subtle and consequently their identification is quite difficult. The features with diagnostic values are the relative size and shape of amphidial fovea, number of subcephalic setae, presence/absence of denticles, de Man ratio a, number of precloacal supplements and length of spicules and gubernaculum. For instance, A. denticulatus differs from A. rigida Schuurmans Stekhoven, 1950 only in the presence of a row of tiny denticles that are not easy to observe. The specimens of A. denticulatus described in this work fit the original description by Wieser (1954) apart from a larger body length of type specimens (male: 2170–2780 µm, female: 2600 µm) vs ours (male: 1234–1745 µm, female: 1299–1796 µm). However, we regard these differences as intraspecific variation among populations.

Figures

Fig. 1. A–D. Acanthopharynx denticulatus Wieser, 1954, ♂. A. Head region. B. Tail region. C. Copulatory apparatus. D. Neck region. E–F. Bolbonema brevicolle Cobb, 1920, ♂. E. Neck region. F. Posterior region with tail end in surface view.

Fig. 2. Acanthopharynx denticulatus Wieser, 1954, SEM microphotographs of ♂. A. Head oblique en face view. B. Cuticle striation at mid-body. C. Cloacal region, from a different ♂ specimen than A, B and D. D. Tail tip, showing ventral bent.