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| Chiloglanis mongoensis
Schmidt & Barrientos, 2019
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Abstract
A recent expedition surveyed freshwater fishes throughout the continental portion of Equatorial Guinea (Rio Muni). This portion of the Lower Guinean ichthyoprovince is relatively unknown with very few collections occurring since the 1960s. Sampling in the Rio Mongo, a tributary to the Rio Wele, yielded two Chiloglanis species; one putatively ascribed to the widespread species C. cameronensis, and the other species having similarities with C. harbinger described from the Lokoundje River in Cameroon. Morphometric analyses between the specimens from Rio Mongo and paratypes of C. harbinger confirm that they are distinct species and should be described as such. Here we describe Chiloglanis mongoensis sp. nov., a narrow endemic species only known from one locality in the Rio Mongo. We provide measurements from paratypes of C. harbinger and emphasize the need for further expeditions in the area.
Keywords: Pisces, Endemism, specimen collection, allometric correction, biodiversity
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| FIGURE 4. Chiloglanis mongoensis, a new species, holotype, USNM 446973, male ALC, 28.0 mm SL; Equatorial Guinea, Centro Sur, Rio Mongo near Mosumu, ..; in dorsal, lateral, and ventral views. Photographs by S. Raredon |
Chiloglanis mongoensis sp. nov.
Diagnosis. Chiloglanis mongoensis is readily distinguished from all other valid species of Chiloglanis with the
exception of C. marlieri and C. harbinger in possessing 28–30 (14+14 – 15+15) mandibular teeth in one row. Chiloglanis mongoensis is distinguished from C. marlieri in possessing a longer dorsal spine (1.8 times into head length
versus 3.1 in C. marlieri). Chiloglanis mongoensis is distinguished from C. harbinger in having fewer premaxillary teeth (99–116 versus 150–224) arranged in fewer rows (4–5 versus 7), a longer dorsal spine (9.0–9.7 versus
7.8–9.0% SL), a deeper body at anus (14.0–16.0 versus 11.7–13.8% SL), a larger eye (3.7–4.6 versus 2.9–3.5% SL),
and a higher adipose fin (2.6–3.9 versus 1.6–2.3% SL; Tables 2 and 3).
Etymology. The specific epithet refers to the Rio Mongo, a tributary to the Rio Wele in Equatorial Guinea,
where the species is presumed endemic.
Distribution. Chiloglanis mongoensis is only known for the type locality. Upstream from the bridge crossing
the Rio Mongo cascades down a bedrock outcrop that is ~3-4 meters high and ~10 meters long. Standing on this
very slippery bedrock we were able to collect several specimens of C. cameronensis and C. mongoensis from cracks
in the bedrock with the electrofisher. After 30 to 45 minutes we collected four C. mongoensis and five C. cameronensis specimens. Though collected in the same microhabitat; it seems likely that further, more focused, collections
would reveal that these two species are occupying different habitats within the Rio Mongo. In co-occurring Chiloglanis species from the Upper Guinea Forest streams in Guinea, Conakry one species is usually found in woody
debris or submerged roots while the other occupies the cobble and larger rocks in the riffles and runs (Schmidt et
al. 2017b). Chiloglanis mongoensis or C. cameronensis specimens were not collected in a small tributary to the Rio
Mongo, but the stream was shallow, substrate was mostly sand and gravel, and there was little flow.
Ray C. Schmidt and Christian Barrientos. 2019. A New Species of Suckermouth Catfish (Mochokidae: Chiloglanis) from the Rio Mongo in Equatorial Guinea. Zootaxa. 4652(3); 507–519. DOI: 10.11646/zootaxa.4652.3.7
