 |
| Chiloglanis frodobagginsi Schmidt, Friel, Bart & Pezold, Schmidt, Bragança, Friel, Pezold, Tweddle & Bart, 2023. DOI: 10.1643/i2022067 Photographs by S. Raredon. |
Abstract
Suckermouth catfishes of the genus Chiloglanis are found throughout tropical Africa. Recent studies highlighted the diversity within this genus remains incompletely documented and nearly 20 new species have been described in the past ten years. Here we describe two new species of Chiloglanis from streams in the Upper Guinean Forest. Chiloglanis fortuitus, new species, is only known from one specimen collected in the St. John River drainage in Liberia and is readily distinguished from other species of Chiloglanis by the number of mandibular teeth and the length of the barbels associated with the oral disc. Chiloglanis frodobagginsi, new species, from the upper Niger River was previously considered to be a disjunct population of C. micropogon. A combination of several characters diagnoses C. frodobagginsi, new species, from topotypic C. micropogon in the Lualaba River (Congo River basin) and from Central African populations of Chiloglanis cf. micropogon in the Benue, Ndian, and Cross River drainages. The biogeographical implications of the recognition of C. frodobagginsi, new species, the likelihood of finding additional diversity in the streams of the Upper Guinean Forests, and the taxonomy of C. micropogon and C. batesii are also discussed.
 |
| Dorsal, lateral, and ventral views of the holotype of Chiloglanis fortuitus, SAIAB 202292, 35.0 mm SL, Liberia, St. John River drainage, Nimba County, Dayea River, above Yekepa, 7.579333°N, 8.516889°W. Scale bar equals 2 mm. Photographs by P. H. N. Bragança. |
Chiloglanis fortuitus, Schmidt, Bragança, and Tweddle, new species
Diagnosis.—Chiloglanis fortuitus is distinguished from all known species of Chiloglanis, including all species in the Upper Guinean Forest, except C. disneyi, C. microps, C. niger, and C. orthodontus, in having 18 mandibular teeth in the functional row (vs. 6–15 teeth; Table 1). Chiloglanis fortuitus is easily distinguished from C. disneyi, C. microps, and C. niger in having longer mandibular barbels whereas these are absent or reduced in the latter species. Chiloglanis fortuitus is distinguished from C. orthodontus in having a more robust oral disc and its length equal to its width versus length much shorter than width (Friel and Vigliotta, 2011). Chiloglanis fortuitus is further distinguished from C. orthodontus in having a longer dorsal spine (12.8 versus 4.1–7.8 % SL) and shorter maxillary barbels (7.2 versus 9.4–14.8 % SL).
Etymology.—The specific epithet is “fortuitus,” referring to the fortuitous aspect of collecting this one specimen at the type locality. The collector, D. Tweddle, sampled fishes at 36 localities in the upper St. John River drainage in Liberia and collected 69 specimens of Chiloglanis at ten of these localities. Additionally, the lot that contained C. fortuitus was one of the three lots borrowed by the lead author to aid with the description of C. tweddlei (Schmidt et al., 2017). The discovery and formal description of C. fortuitus is fortuitous in several aspects.
 |
| Dorsal, lateral, and ventral views of Chiloglanis frodobagginsi holotype, TU 203552, 24.1 mm SL, Guinea, Niger River drainage, Niger River, North of Faranah, on road N29, 10.28382°N, 10.76925°W. Scale bar equals 2 mm. Photographs by S. Raredon. |
Chiloglanis frodobagginsi, Schmidt, Friel, Bart, and Pezold, new species
Diagnosis.—Chiloglanis frodobagginsi is distinguished from all known species of Chiloglanis in the Upper Guinean Forests, and most of the other described species (except C. disneyi, C. harbinger, C. marlieri, C. micropogon, C. microps, C. mongoensis, and C. niger) by the very reduced, or absent, mandibular barbels on the oral disc. Chiloglanis frodobagginsi can be distinguished from C. disneyi, C. harbinger, C. marlieri, C. microps, C. mongoensis, and C. niger in having fewer mandibular teeth in one row (10–12 versus 16–20, 26–30, 26–28, 16–18, 28, and 16–20 respectively). Chiloglanis frodobagginsi is distinguished from C. batesii in having two prominent papillae on the roof of the oral cavity; versus the absence of papillae in C. batesii. This species is further distinguished from C. batesii in having shorter and more blunt mandibular teeth arranged in bunched rows; versus sharper, more elongate, and disordered mandibular teeth. Chiloglanis frodobagginsi also has a fleshy unpapillated ridge posterior to the mandibular teeth versus several large papillae in C. batesii (Friel and Vigliotta, 2011).
A unique combination of characters distinguishes C. frodobagginsi from the closely related C. micropogon and C. cf. micropogon from Central Africa. As compared to C. micropogon from the Lualaba River, C. frodobagginsi has a larger eye diameter (4.2–6.5 versus 4.7–5.5 % SL; Supplemental Fig. A; see Data Accessibility), longer maxillary barbels (3.8–7.2 versus 3.4–6.5 % SL; Supplemental Fig. A; see Data Accessibility), a narrower mandibular tooth row (1.6–2.8 versus 2.4–3.1 % SL; Supplemental Fig. A; see Data Accessibility), a longer distance between dorsal fin and adipose fin (14.4–21.5 versus 14.9–18.8 % SL; Fig. 4A), and a shorter anal-fin base length (8.0–10.8 versus 9.7–12.7 % SL; Supplemental Fig. A; see Data Accessibility). Chiloglanis frodobagginsi is further distinguished from C. micropogon in having fewer premaxillary teeth (36–70 versus 62–103) scattered in three rows versus four (Fig. 4B; Table 2). While the ranges of these measurements and counts overlap, these distinctions hold true when comparing similar sized species (Fig. 4; Supplemental Fig. A; see Data Accessibility). Compared to Chiloglanis cf. micropogon from the Benue, Ndian, and Cross River basins Chiloglanis frodobagginsi has a narrower occipital shield (3.0–4.0 versus 4.0–5.4 % SL), a shorter dorsal fin to adipose fin distance (14.5–21.5 versus 19.3–24.2), and a narrower mandibular tooth row (1.6–2.8 versus 1.8–3.2 % SL).
Etymology.—Chiloglanis frodobagginsi is named after another diminutive traveler, Frodo Baggins, a fictional character well known from J. R. R. Tolkien's The Lord of the Rings series. Roughly 3,000 miles (4,800 km) separate C. frodobagginsi in the upper Niger River drainage and C. micropogon, the sister species, found in the Congo River basin. Another seemingly closely related species, Chiloglanis cf. micropogon, is found in the southern Benue drainage and in several small coastal rivers about 3,000 km from the upper Niger River drainage (e.g., Cross and Ndian Rivers). It is unclear whether these species are descended from a more widespread species, or the result of dispersal from the Congo River basin into the Niger River drainage, via the Benue River, and then up to the headwaters of the Niger River. This was an incredible journey for such a small and seemingly non-vagile fish.
Ray C. Schmidt, Pedro H. N. Bragança, John P. Friel, Frank Pezold, Denis Tweddle and Henry L. Bart Jr. 2023. Two New Species of Suckermouth Catfishes (Mochokidae: Chiloglanis) from Upper Guinean Forest Streams in West Africa. Ichthyology & Herpetology. 111(3); 376-389. DOI: 10.1643/i2022067
