Chordodes bipilus Kirjanova, 1957

Schmidt-Rhaesa, Andreas & Karraker, Nancy E., 2017, Nematomorpha from Hong Kong and description of a new species from Malaysia, Zootaxa 4238 (3), pp. 395-405 : 398

Chordodes bipilus Kirjanova, 1957

( Figure 2A, B )

Material examined. One male from Tai Po Kau stream in Tai Po Kau Country Park, Hong Kong (UTM Zone 50Q, 2482673N/209867E), elevation 163 m. Collected by N.E. Karraker on August 1, 2008. Deposited in the Zoological Museum Hamburg, accession numbers V13393 .

Description. The specimen is 240 mm long and has a diameter of 1.1 mm. The body color is medium brown, and a pattern of darker patches (“leopard pattern”) is present. Simple areoles are irregular in shape and have an uneven surface, but without bristles ( Fig. 2A ). Some areoles are slightly larger and more elevated than others and have a stronger structured surface ( Fig. 2A ). These areoles might represent bulging areoles. Tubercle areoles and thorn areoles are present ( Fig. 2A ). Crowned areoles occur in clusters surrounded by 10–12 circumcluster areoles ( Fig. 2A, B ). Crowned areoles are densely covered by apical filaments of different lengths and thicknesses ( Fig. 2A, B ). The filament diameter ranges from 0.75 to 1.25 µm. Some of the bristles are branching, either into two equal branches or give off smaller branches ( Fig. 2A, B ). Most filaments are not longer than 20 µm, but few longer ones are present.

Remarks. The cuticular pattern of this specimen fits well to the description of Chordodes bipilus Kirjanova, 1957 , a species from Iran. This species is documented by drawings and the most conspicuous character, the presence of two types of filaments on the crowned areoles, is not documented. Kirjanova (1957) describes simple areoles with an irregular surface, the presence of tubercle and thorn areoles, crowned areole clusters composed of a pair of crowned areoles and 9–12 circumcluster areoles. The crowned areoles have apical filaments of two sizes, longer and thicker ones (diameter 2 µm) as well as shorter and thinner ones (diameter 1 µm). All these characters correspond to our specimen. The apical filaments of the Hong Kong specimen do not strictly belong to two size classes, but there are transitions in size. Some of the smaller filaments are the result of branches from larger ones. Such patterns have not been previously described from C. bipilus , but this may be due to researchers not having used SEM.

In addition, bulging areoles are described by Kirjanova (1957), which may be present, but are not as clear in the Hong Kong specimen as in the original description. Kirjanova (1957) also described crowned areoles with very long apical filaments from the ventral side. It cannot be excluded that the very few long filaments in the Hong Kong specimen belong to crowned areoles with long filaments, in which most filaments were broken off, but a restriction of such areoles to the ventral side could not be observed. Therefore it is more likely that these filaments represent single cases of extraordinarily long filaments. This pattern fits well to a general pattern in Chordodes . Crowned areoles with long filaments are abundantly described from females, but are usually, though not always, absent in males. The Iran specimen is a female ( Kirjanova 1957), and the Hong Kong specimen is a male.

Figures

FIGURE 2. A, B. Chordodes bipilus (V 13393). A. Cuticular structures showing crowned areole cluster, two types of simple areoles (sar 1 and sar 2), thorn (thar) and tubercle (tuar) areoles. Unlabelled circle shows branching of apical filaments in the crowned areoles. B. Magnification of crowned areole cluster, unlabelled circle see A. C – E. Chordodes caledoniensis (V 13394). C. Overview on the cuticle showing simple areoles and clusters of crowned areoles with crowned areoles (crar) and circumcluster areoles (ccar). D. Magnification of crowned areole cluster. Arrows show simple areoles with “ knobby ” surface. E. Crowned areoles with long apical filaments along both sides of the ventral midline (vml).