Meteterakis saotomensis n. sp. (Nematoda: Heterakidae) from Schistometopum thomense (Bocage) (Gymnophiona: Dermophiidae) on São Tomé Island

Abstract

Meteterakis saotomensis n. sp. is described from Schistometopum thomense (Bocage), a gymnophionan endemic to the oceanic island of São Tomé in the Gulf of Guinea. The specimens were assigned to Meteterakis Karve, 1930, based on the possession of a head with three rounded lips, not set-off from the body, the absence of interlabia and cordons, females with a long vagina and males with a preanal sucker, surrounded by a cuticularised rim and caudal alae that are supported by fleshy papillae. The new species is characterised by: body length 4.2-4.5 mm (males) and 5.1-6.4 mm (females); total length of oesophagus, including pharyngeal portion and oesophageal bulb, 820-856 µm (males) and 898-1,070 µm (females); length of pharynx 57-58 µm (males) and 65-68 µm (females); spicules equal, 410-521 µm long, with tessellated ornamentation throughout their length and alae, and with bevelled tip; gubernaculum or 'gubernacular mass' absent; tail length 164-176 µm (males) and 214-239 µm (females), with elongated tip; vulva at 2.3-2.8 mm from anterior end, with anterior lip forming small flap. This is the second species of Meteterakis reported from gymnophionan hosts and the first from the Afrotropical region. Selected comparative morphological data for Meteterakis spp. are presented, and data on host range and geographic distribution are updated. The name M. striaturus Oshmarin & Demshin, 1972 is corrected to M. striatura to reflect the female gender of the genus name.

Two new skink-endoparasitic species of Meteterakis (Nematoda, Heterakidae, Meteterakinae) from East Asian islands

“…In addition to the spicule length, the new species is distinguishable from the eight congeners by the following characteristics of spicules: proximal end wide, funnel-shaped and ventrally bent vs. proximal end slightly widened in M. ishikawanae (Hasegawa 1987) and M. wonosoboensis Purwaningshi, 2015 or vs. proximal end straight in M. guptai Gupta &Naiyer, 1993 andM. triaculeata (Kreis, 1933) (Inglis 1958); surface smooth, vs. rough surface in M. saotomensis Junker et al, 2015; and spicule alae narrow vs. wider in M. baylisi Inglis, 1958, M. crombiei Bursey et al, 2005and M. sinharajensis Crusz & Ching, 1975.…”

“…The spicule length, which has been regarded as a useful taxonomic character of the genus Meteterakis (e.g. Junker et al 2015), exhibits certain intraspecific variations. Moreover, the characteristic of spicule length sometimes overlaps with those of other congeners.…”

“…Meteterakis Karve, 1930 is a parasitic nematode genus, which is specific to amphibians (frogs and caecilians) and reptiles (lizards and land turtles) (Baker 1984, Hasegawa and Asakawa 2004, Zhang and Zhang 2011, Junker et al 2015, and currently consists of 27 species. They are distributed in South, Southeast and East Asian regions, as well as in Oceania and Sao Tome Island, which is in the Gulf of Guinea (Baker 1984, Junker et al 2015.…”

“…Meteterakis Karve, 1930 is a parasitic nematode genus, which is specific to amphibians (frogs and caecilians) and reptiles (lizards and land turtles) (Baker 1984, Hasegawa and Asakawa 2004, Zhang and Zhang 2011, Junker et al 2015, and currently consists of 27 species. They are distributed in South, Southeast and East Asian regions, as well as in Oceania and Sao Tome Island, which is in the Gulf of Guinea (Baker 1984, Junker et al 2015. Four species of Meteterakis have been recorded from the East Asian islands, which consist of the islands from the Japanese Archipelago to Taiwan: M. japonica (Wilkie, 1930), inhabiting the eastern Japanese Archipelago and Shimokoshikijima Island, an islet west off Kyushu, western Japan; M. amamiensis Hasegawa, 1990, indigenous to the western Japanese Archipelago and northern the Ryukyu Archipelago (Kodakarajima and Amamioshima Islands); M. ishikawanae Hasegawa, 1987, described from the Okinawan Islands; and the Burmese M. govindi Karve, 1930, which is the type species of the genus, from southern Taiwan (Karve 1930, Wilkie 1930, Yamaguti 1935, 1941, Hasegawa 1987, 1990, 1992, Telford Jr 1997, Goldberg and Bursey 2002, Norval et al 2014, Sata 2015, 2018.…”

The Amphibians of the Gulf of Guinea Oceanic Islands

“…The ecology and behavior of all the island species are incompletely understood, including basic aspects of reproductive biology (e.g., L. palmatus) and dependence on particular habitats (e.g., P. newtoni, H. thomensis), which are likely important considerations for effective conservation management. Like most vertebrates, São Tomé and Príncipe's amphibians also serve as hosts for many parasites, including the fungal pathogen Bd and a recently described nematode (Meteterakis saotomensis; Junker et al 2015), but the diversity of this microfauna and potential impacts on the amphibian hosts are poorly known. For instance, a recent study identified cryptic infection of P. leveleve (misidentified as P. dispar in the study) tadpoles by Perkinsea protists (Chambouvet et al 2015) that have caused mass mortality events in the United States (Davis et al 2007).…”