Chordodes cf. moutoni Camerano, 1895

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 : 400-402

Chordodes cf. moutoni Camerano, 1895

( Figure 3 )

Material examined. Seven males from Peel Rise stream in Aberdeen Country Park , Hong Kong (UTM Zone 50Q, 2464218N/206695E), elevation 172 m. Collected by N.E. Karraker on July 26, 2008 ( V13395 ) , November 27, 2009 ( V13396 , 13397) and July 2, 2012 ( V13398 - V13401 ). Deposited in the Zoological Museum Hamburg, accession numbers V13395 - V13401 .

Description. The specimens measure 265, 190, 150, 185, 175, 155 and 180 mm in length and have a diameter of 1.0, 1.0, 1.3, 1.3, 1.1, 1.1 and 0.9 mm, respectively ( V13395 - V13401 ). The body color is medium to dark brown and, with exception of V13395 , a pattern of darker patches (“leopard pattern”) is present. All specimens correspond in the following characters. Simple areoles are flat with irregular surface. Larger and more elevated areoles with fine bristles on top ( Fig. 3 A–C) represent bulging areoles. Tubercle and thorn areoles are both present ( Fig. 3 A–C, G). Clusters of crowned areoles are composed of a pair of crowned areoles with moderately long apical filaments and 10–12 circumcluster areoles that resemble bulging areoles in structure ( Fig. 3 A–C, E, F). The apical bristles in some specimens ( V13395 , V13399 ) originate laterally on the more or less flat apical surface of the areole ( Fig. 3 F), in other specimens they form an irregular tuft ( Fig. 3 E). It cannot be excluded that in the tuft the filaments also originate in a lateral way, but then curve into all directions and cover the apical surface of the areoles. Crowned areoles with long filaments are present flanking the ventral midline in specimens V13395 to 13398 ( Fig. 3 D), but were not observed in the other three specimens.

All specimens are males. The ventral cloacal opening is about 260 µm from the posterior tip, and is surrounded by circumcloacal spines ( Fig. 3 H, K, L). In the region around the cloacal opening are numerous spines in distinctive distribution patterns. Spines of different lengths (maximally 12 µm) are present mainly posterior of the cloacal opening ( Fig. 3 I, K, L). They have a more or less blunt tip ( Fig. 3 I). Anterolateral of the opening are two fields of approximately 100 µm in length and 65 µm in width that contain pointed spines (length about 12 µm) ( Fig. 3 K, L). Similar spines are present and scattered between the areoles that are present on the lateral and dorsal side of the posterior end; spines are concentrated at the posterior tip.

Remarks. The cuticular pattern corresponds well with the description for Chordodes moutoni Camerano, 1895 or, to be more precise, it falls into the range of characters described for this species. Chordodes moutoni was originally described from China, from a locality called “Ho Chan in the province Ngan Haei” ( Camerano 1895, reinvestigation by Zanca & De Villalobos 2005), located as Henan Province by Zanca & De Villalobos (2005). Other specimens from China ( Wu & Tang 1933), Malaysia ( Camerano 1899, 1901, Schmidt-Rhaesa & Brune 2008) and India ( Schmidt-Rhaesa & Yadav 2013, Schmidt-Rhaesa et al. 2015) were assigned to this species. Specimens assigned as C. cf. moutoni were described from the Philippines ( Schmidt-Rhaesa & Schwarz, 2016).

Most characters of C. moutoni are broadly present among Chordodes species. Tubercle and thorn areoles, crowned areoles and circumcluster areoles in the described form are observed in several species (Schmidt-Rhaesa et al. 2008). One particularly notable character for C. moutoni is probably the presence of variable shapes and forms in the simple areoles. Generally, these can be divided into two types, a lower one (simple areoles) and a more elevated one with bristles on top (bulging areoles). There may be transitions between these two types. The reinvestigation of the type material ( Zanca & De Villalobos 2005) shows quite flat areoles, while the Hong Kong specimens resemble more the drawing of the type material ( Camerano 1897). The specimens assigned to C. moutoni from Malaysia (Cameron Highlands, Schmidt-Rhaesa & Brune 2008) do show uniform simple areoles and no bulging areoles, therefore the placement in this species might be not correct. Chordodes moutoni seems to be a species without very prominent and unique characters, which makes it possible that it serves as a collection of several species with equally less prominent characters. Barcoding would help greatly in getting a better picture of species boundaries in this species.

One peculiar character is the presence of crowned areoles with very long apical filaments on the ventral side of some of the males investigated here. Such areoles are present in females of many species, but only in males of very few species (Schmidt-Rhaesa et al. 2008). In C. moutoni these areoles have been reported so far only from females ( Camerano 1895, Zanca & De Villalobos 2005, Schmidt-Rhaesa & Yadav 2013, Schmidt-Rhaesa et al. 2015) and their occurrence in some of the males may be an indication that the Hong Kong specimens belong to a different species. However, as the standard technique some time ago used to be to cut a random piece of cuticle, certain types of areoles with particular distribution patterns may have been overlooked.

The description of posterior ends in males (and also in females) in the genus Chordodes often does not receive as much attention as the description of the cuticular structure. This may be because the general patterns of the distribution of spines look quite similar. In most species, there is a circle of spines around the cloacal opening (circumcloacal spines). Short spines are present in the ventral region around the cloacal opening and spines are present in paired fields or rows anterolateral of the cloacal opening. Concerning C. moutoni , there is one difference as Zanca & De Villalobos (2005) describe anterolateral rows of bristles (measurements approximately 185 x 26 µm), while in the Hong Kong specimens oval fields were found.

Figures

FIGURE 3. Chordodes cf. moutoni. A – C. Cuticular structure in three specimens showing crowned areole clusters (ccl), thorn areoles (thar) and tubercle areoles (tuar) among simple areoles. D. Crowned areoles with very long apical filaments, arrows point at thorn areoles. E. Crowned areoles with apical filaments as a tuft (crar = crowned areoles, ccar = circumcluster areoles). F. Crowned areoles with apical filaments originating laterally. G. Thorn and tubercle areole in magnification. H. Cloacal opening (co) surrounded by circumcloacal spines. I. Blunt spines from the region posterior of the cloacal opening. K, L. Ventral view on male posterior ends showing position of the cloacal opening (co) and the anterolateral bristlefields (bf). A, F from V 13395, B, L from V 13400, C from V 13399, D, E, G – K from V 13398.