Hystrignathus dearmasi, Morffe, Jans & Garcia, Nayla, 2010

Morffe, Jans & Garcia, Nayla, 2010, Hystrignathus dearmasi sp. n. (Oxyurida, Hystrignathidae), first record of a nematode parasitizing a Panamanian Passalidae (Insecta, Coleoptera), ZooKeys 57, pp. 1-8 : 2-4

Hystrignathus dearmasi sp. n. Fig. 1 A–HFig. 2 A–E

Type material.

♀ holotype, Panama, Panama Province, Summit National Park; in unidentified short, blackish Passalidae ; 25.IX.2009; L. F. de Armas coll.; CZACC 11.4604. Paratypes: 6 ♀♀, same data as holotype, CZACC 11.4605-11.4610; 2 ♀♀, CHIOC, same data as holotype.

Measurements.

Holotype (female) a = 8.62, b = 4.89, c = 7.24, V% = 57.46, total length = 1.810, maximum body width = 0.210, first cephalic annule ( length×width) = 0.013 × 0.055, stoma length = 0.045, procorpus length = 0.295, isthmus length = 0.025, diameter of basal bulb = 0.090, total length of oesophagus = 0.370, nerve ring to anterior end = 0.213, excretory pore to anterior end = 0.480, vulva to posterior end = 0.770, anus to posterior end = 0.250, eggs = 0.095 –0.110×0.043– 0.048 (0.099 ± 0.007 × 0.046 ± 0.002 n = 4).

Paratypes (females) (n = 8): a = 7.81-9.37 (8.61 ± 0.58 n = 8), b = 4.17-5.35 (4.84 ± 0.51 n = 6), c = 6.19-8.16 (7.14 ± 0.59 n = 8), V% = 54.27-60.00 (56.69 ± 2.05 n = 7), total length = 1.300-1.780 (1.549 ± 0.179 n = 8), maximum body width = 0.158-0.210 (0.180 ± 0.019 n = 8), first cephalic annule ( length×width) = 0.010 –0.015×0.048– 0.055 (0.013 ± 0.001 × 0.052 ± 0.003 n = 7), stoma length = 0.038-0.045 (0.041 ± 0.004 n = 8), procorpus length = 0.230-0.273 (0.248 ± 0.016 n = 8), isthmus length = 0.020 (n = 1), diameter of basal bulb = 0.070-0.085 (0.077 ± 0.005 n = 8), total length of oesophagus = 0.300-0.350 (0.325 ± 0.019 n = 6), nerve ring to anterior end = 0.175-0.190 (0.184 ± 0.007 n = 4), excretory pore to anterior end = 0.420-0.450 (0.433 ± 0.015 n = 4), vulva to posterior end = 0.590-0.770 (0.686 ± 0.073 n = 7), anus to posterior end = 0.190-0.250 (0.218 ± 0.023 n = 8), eggs = 0.088 –0.103×0.038– 0.055 (0.097 ± 0.005 × 0.046 ± 0.004 n = 16).

Description.

Female body robust, slightly fusiform. Cuticle strongly annulated in spiny region (annule c.5 µm width) and less in rest of body. Cervical cuticle armed with spines from some distance beyond stoma (distance about length of stoma) almost to end of procorpus. Spines arranged initially in c. 16 apposite rows that do not seem to increase consistently where they terminate. Anterior spines short and wide, scale-like, becoming sharply pointed but still short toward end of rows. Sub-cuticular longitudinal striae present. Lateral alae absent. Head bearing 8 paired papillae, set-off from body by single groove. First cephalic annule cone-like and truncated, not inflated, c.1.5 head lengths long. Stoma short, wide, about 4 first annule lengths long, surrounded by oesophageal collar. Oesophagus consists of muscular procorpus whose diameter increases slightly and gradually, well set-off from short isthmus. Intestine simple, sub-rectilinear, its fore region inflated. Rectum short, anus not prominent. At least with 2, large, ovoid, rectal glands with central nuclei at level of rectum. Nerve ring encircles procorpus at about its midpoint. Excretory pore located at about half of body width posterior to basal bulb. Vulva a median transverse slit slightly displaced towards posterior half of body, lips very prominent. Vagina muscular, forwardly directed. Genital tract didelphic-amphidelphic. Ovaries reflexed. Anterior ovary shorter, reflexed just posterior excretory pore, posterior ovary reflexed at slightly more than body width before anus. Both flexures about 2 body-widths long. Eggs ovoid, numerous, bearing 8 longitudinal, slightly prominent ridges on shell. Tail comparatively short, conical, attenuated, sharply pointed. Male unknown.

Differential diagnosis.

Hystrignathus dearmasi sp. n. is similar to Hystrignathus cobbi Travassos & Kloss, 1957 from Brazil, since both have a similar form of the cephalic end, spines commencing posterior to the stoma (feature unique in the genus) and the apparent absence of lateral alae ( Travassos and Kloss 1957b). From the latter, Hystrignathus dearmasi sp. n. differs by having the body consistently shorter (1.300-1.81 vs. 2.432-2.79), but the tail (c = 6.19-8.16 vs. 14.48-16.61) and oesophagus (b = 4.17-5.35 vs. 5.68-6.30) comparatively longer. The vulva is located further forward in Hystrignathus dearmasi sp. n. (V%: 54.27-60.00 vs. 62.25-64.37). The eggs of Hystrignathus cobbi have smooth shells instead of the ridged eggs of Hystrignathus dearmasi sp. n.

Hystrignathus heliae Travassos & Kloss, 1957, from Brazil, has a similar cephalic end, but can be differentiated by the length of the stoma, which hardly surpasses the base of the first cephalic annule, and spines starting at the end of the cephalic annule. In Hystrignathus dearmasi sp. n. the stoma is notably longer and the spines commence at some distance posterior to it.

Type host.

Unidentified, short, blackish passalid beetle ( Coleoptera : Passalidae ).

Site.

Gut caeca.

Type locality.

Summit National Park, Panama Province, Panama.

Etymology.

The specific epithet honours Dr. Luis F. de Armas Chaviano, an eminent Cuban aracnologist and the collector of the type-host.