Research Article |
Corresponding author: Tadiwa I. Mutizwa ( timutizwa@gmail.com ) Academic editor: Maria Elina Bichuette
© 2024 Tadiwa I. Mutizwa, Wilbert T. Kadye, Pedro H. N. Bragança, Taurai Bere, Albert Chakona.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Mutizwa TI, Kadye WT, Bragança PHN, Bere T, Chakona A (2024) Hidden in the riffles: A new suckermouth catfish (Mochokidae, Chiloglanis) from the middle Zambezi River system, Zimbabwe. ZooKeys 1197: 57-91. https://doi.org/10.3897/zookeys.1197.114679
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The recent surge in the discovery of hidden diversity within rheophilic taxa, particularly in West and East Africa, prompted a closer examination of the extent to which the current taxonomy may obscure the diversity of riffle-dwelling suckermouth catfishes in the genus Chiloglanis in southern Africa. Currently, the region comprises eight valid species within this genus. Seven of them have relatively narrow geographic distribution ranges except for C. neumanni, which is considered to be widely distributed, occurring from the Buzi River system in the south, and its northern limit being the eastward draining river systems in Tanzania. Recent surveys of the middle Zambezi River system revealed Chiloglanis specimens that were distinguishable from the known species of the genus from southern Africa. Integration of molecular and morphological data indicated that these specimens from the Mukwadzi River represent a new species to science, herein described as Chiloglanis carnatus Mutizwa, Bragança & Chakona, sp. nov. This species is readily distinguished from its southern African congeners by the possession of a distinctive extended dermal tissue covering the base of the dorsal fin and the possession of ten mandibular teeth (vs 8, 12, or 14 in the other taxa). Results from this study add to the growing evidence of a high level of undocumented diversity within riffle-dwelling taxa in southern Africa.
Diversity, freshwater, integrative taxonomy, rheophilic taxa, southern Africa
Rheophilic habitats are characterised by fast flowing water and rocky substratum, which provide a wide range of specialised niches for distinct aquatic taxa adapted to these environments (
The Mochokidae is the most species-rich freshwater catfish family that is endemic to Africa (
Distribution of Chiloglanis species in southern Africa based on data from the National Research Foundation-South African Institute for Aquatic Biodiversity extracted from the GIBF database (https://www.gbif.org).
Uncertainties about the identity of the broadly distributed C. neumanni in southern Africa have persisted for decades. This species was described from the Bubu River, a tributary of the Great Ruaha River basin in Tanzania, and was considered to be distributed across several eastern, central, and southern African river systems (
During surveys of the southern tributaries of the middle Zambezi River system in 2016 and 2019, morphologically distinct suckermouth catfishes were collected from the Mukwadzi River that drains the western margin of the Great Dyke in Zimbabwe. These specimens could not be attributed to any of the currently described species or recently identified lineages of Chiloglanis from this region. The present work represents the first in a series of studies that aim to resolve the taxonomy of suckermouth catfishes of southern Africa. This study applied integrative taxonomic approaches combining genetic and morphological data to determine the taxonomic distinctiveness of the recently collected specimens from the middle Zambezi River. The significance and implications of incomplete documentation of the diversity of rheophilic species in a region where their unique habitats are under threat from multiple environmental impacts are discussed.
Specimens were collected from two sites in the Mukwadzi River, a tributary of the Manyame River, a south bank affluent of the middle Zambezi River, during surveys in 2016 and 2019. Samples were collected using a battery-powered Samus 725GN backpack electric fisher with a block net placed downstream to capture dislodged animals in the fast-flowing current. The specimens were photographed to document the live colour pattern then euthanized with clove oil. Muscle tissue from the right side of the specimens was cut out and preserved in 99% ethanol for molecular analysis. Voucher specimens for morphological studies were fixed in 10% formalin in the field and subsequently transferred to 70% ethanol for long term preservation. Additional tissue samples and voucher specimens used in the present study were obtained from the National Fish Collection at the National Research Foundation-South African Institute for Aquatic Biodiversity (NRF-SAIAB) in Makhanda (Tables
List of 80 COI sequences used in the present study including six new sequences of the specimens from the Mukwadzi River. The new sequences (in bold) include the hologenetype identified by an asterisk (*) and paragenetypes identified by a plus (+).
Species name | River system | GPS coordinates (Latitude, Longitude) | COI sequence ID |
---|---|---|---|
Atopochilus savorgnani | Congo | – | MK073983 |
Congo | – | MK073984 | |
Chiloglanis anoterus | Mlumati | -25.7567, 31.4386 | LN610269 |
Mlumati | -25.7692, 31.3367 | LN610270 | |
Mlumati | -25.7692, 31.3367 | LN610271 | |
Mlumati | -25.8672, 31.3347 | LN610272 | |
Chiloglanis bifurcus | Mlumati | – | MH432062 |
Mlumati | – | SB8458 | |
Mlumati | – | SB8462 | |
Chiloglanis fasciatus | Okavango | -13.5943, 16.8805 | ANGFW077-12 |
Okavango | -12.6713, 16.1114 | ANGFW131-12 | |
Okavango | -12.6713, 16.1114 | ANGFW132-12 | |
Okavango | -12.6713, 16.1114 | ANGFW133-12 | |
Okavango | -12.6713, 16.1114 | ANGFW134-12 | |
Chiloglanis paratus | Phongolo | – | MPUMA025 |
Phongolo | – | SB8459 | |
Chiloglanis pretoriae | Limpopo | -23.9904, 31.8258 | LN610341 |
Chiloglanis sp. ‘dwarf’ | Honde | -18.4337, 32.8969 | MH432047 |
Honde | -18.5992, 32.729 | MH432054 | |
Makanga | -18.5438, 32.8013 | MH432044 | |
Mupenga | -18.5725, 32.8038 | MH432042 | |
Mupenga | -18.5725, 32.8038 | MH432048 | |
Mutarazi | -18.5324, 32.8075 | MH432018 | |
Chiloglanis sp. ‘dwarf’ | Mutarazi | -18.5324, 32.8075 | MH432019 |
Mutarazi | -18.5324, 32.8075 | MH432032 | |
Nyamhingura | -18.3696, 32.9354 | MH432025 | |
Nyamhingura | -18.3696, 32.9354 | MH432026 | |
Nyamhingura | -18.3696, 32.9354 | MH432027 | |
Phalombe | -15.81, 35.646 | MAFW097 | |
Pungwe | -18.3955, 32.9707 | MH432030 | |
Pungwe | -18.3955, 32.9707 | MH432031 | |
Pungwe | -18.45, 32.8968 | MH432046 | |
Pungwe | -18.45, 32.8968 | MH432057 | |
Pungwe | -18.3955, 32.9707 | MH432061 | |
Ruo | -16.0403, 35.6633 | MAFW029 | |
Chiloglanis sp. ‘Shire’ | Shire | -15.061, 35.219 | MAFW119 |
Chiloglanis carnatus sp. nov. | Manyame | -17.4249, 30.5854 | PP156890 * |
Manyame | -17.4249, 30.5854 | PP156891 + | |
Manyame | -17.4249, 30.5854 | PP156892 + | |
Manyame | -17.4249, 30.5854 | PP156893 + | |
Manyame | -17.4249, 30.5854 | PP156894 + | |
Manyame | -17.4249, 30.5854 | PP156895 + | |
Chiloglanis sp. ‘Nyangombe’ | Chidya | -18.2653, 32.5903 | MH432020 |
Chidya | -18.2653, 32.5903 | MH432021 | |
Chidya | -18.2653, 32.5903 | MH432022 | |
Chidya | -18.2653, 32.5903 | MH432033 | |
Chiloglanis sp. ‘Pungwe’ | Chiyengwa | -18.6878, 32.922 | MH432040 |
Honde | -18.5992, 32.729 | MH432049 | |
Pungwe | -18.3955, 32.9707 | MH432028 | |
Pungwe | -18.3955, 32.9707 | MH432029 | |
Chiloglanis sp. ‘roughskin’ | Buzi | -19.932, 33.826 | SAFW910 |
Chiyengwa | -18.6878, 32.922 | MH432045 | |
Chiyengwa | -18.6878, 32.922 | MH432051 | |
Honde | -18.5438, 32.8044 | MH432036 | |
Makanga | -18.5438, 32.8013 | MH432043 | |
Mupenga | -18.5725, 32.8038 | MH432038 | |
Mupenga | -18.5725, 32.8038 | MH432039 | |
Mupenga | -18.5725, 32.8038 | MH432041 | |
Mupenga | -18.5725, 32.8038 | MH432060 | |
Ngarura | -18.5474, 32.8718 | MH432052 | |
Ngarura | -18.5474, 32.8718 | MH432053 | |
Ngarura | -18.5474, 32.8718 | MH432059 | |
Nyamukombe | -18.3821, 33.0327 | MH432034 | |
Nyamukombe | -18.3821, 33.0327 | MH432035 | |
Nyamukombe | -18.3821, 33.0327 | MH432058 | |
Nyamukwara | -18.6918, 32.9236 | MH432055 | |
Nyamukwara | -18.6918, 32.9236 | MH432056 | |
Pungwe | -18.4414, 32.8875 | MH432050 | |
Rwera | -18.5434, 32.8044 | MH432037 | |
Chiloglanis sp. ‘Zambezi’ | Zambezi | -15.656, 30.953 | SAFW893 |
Nyangombe | -18.0829, 32.5819 | MH432023 | |
Nyangombe | -18.0829, 32.5819 | MH432024 | |
Okavango | -14.9397, 17.7188 | ANGFW015-12 | |
Okavango | -13.5943, 16.8805 | ANGFW078-12 | |
Okavango | -14.6497, 16.9066 | ANGFW211-12 | |
Chiloglanis swierstrai | Phongolo | – | SB8457 |
Phongolo | – | SB8460 | |
Phongolo | – | SB8461 | |
Euchilichthys boulengeri | Dipumu | -6.0045, 22.3905 | HM418085 |
Euchilichthys royauxi | Epulu | – | KT192823 |
List of 184 specimens examined in this study including 19 specimens collected from the Mukwadzi River.
Species | Type status | Catalogue No. | No. specimens | River system | Latitude, Longitude |
---|---|---|---|---|---|
Chiloglanis anoterus | Holotype | SAIAB 186246 | 1 | Phongola | -27.5, 30.4667 |
Chiloglanis bifurcus | Holotype | SAIAB 120160 | 1 | Incomati | -25.4333, 30.7167 |
Paratype | SAIAB 120161 | 6 | Incomati | -25.4333, 30.7167 | |
Paratype | SAIAB 120529 | 3 | Incomati | -25.3833, 30.35 | |
Chiloglanis emarginatus | Holotype | SAIAB 120117 | 1 | Incomati | -25.9833, 30.6833 |
Paratype | SAIAB 120118 | 9 | Incomati | -25.85, 30.2 | |
Chiloglanis fasciatus | _ | SAIAB 204928 | 6 | Okavango | -14.3872, 16.2876 |
_ | SAIAB 204916 | 4 | Okavango | -14.387, 16.2873 | |
Chiloglanis carnatus sp. nov. | Holotype | SAIAB 236631 | 1 | Manyame | -17.4249, 30.5854 |
Paratype | SAIAB 211349 | 13 | Manyame | -17.4244, 30.5845 | |
Paratype | SAIAB 211346 | 5 | Manyame | -17.4249, 30.5854 | |
Chiloglanis paratus | Holotype | SAIAB 186248 | 1 | Phongola | -27.3833, 31.5 |
Paratype | SAIAB 120050 | 1 | Incomati | _ | |
Chiloglanis swierstrai | Paratype | SAIAB 30013 | 1 | Phongola | -25.6667, 27.8333 |
Paratype | SAIAB 21805 | 5 | Phongola | -27.4333, 31.5167 | |
Holotype | SAIAB 186247 | 1 | Phongola | -27.4167, 31.1833 | |
Chiloglanis pretoriae | _ | SAIAB 82972 | 10 | Limpopo | -23.0105, 30.4785 |
_ | SAIAB 70603 | 3 | Incomati | -25.8478, 27.7836 | |
_ | SAIAB 70822 | 3 | Limpopo | -25.3883, 28.3117 | |
Chiloglanis neumanni | Lectotype | BMNH190575249 | 1 | Bubu | _ |
Paralectotype | BMNH190575250 | 1 | Bubu | _ | |
Paralectotype | BMNH190575250 | 1 | Bubu | _ | |
Chiloglanis sp. ‘rough skin’ | _ | SAIAB 201075 | 4 | Pungwe | -18.4414, 32.8875 |
_ | SAIAB 201095 | 2 | Chiyengwa | -18.6878, 32.922 | |
_ | AC14CL10 | 11 | Mupenga | -18.5725, 32.8038 | |
_ | SAIAB 200955 | 5 | Ngarura | -18.5474, 32.8718 | |
_ | SAIAB 200933 | 9 | Nyamukombe | -18.3821, 33.0327 | |
_ | SAIAB 201035 | 15 | Rwera | -18.5434, 32.8044 | |
_ | SAIAB 201047 | 3 | Nyamukombe | -18.3821, 33.0327 | |
_ | SAIAB 201088 | 8 | Nyamukwara | -18.6918, 32.9236 | |
_ | SAIAB 201026 | 8 | Honde | -18.5438, 32.8044 | |
Chiloglanis sp. ‘dwarf’ | _ | AC14CL10 | 10 | Mupenga | -18.5725, 32.8038 |
_ | SAIAB 200940 | 3 | Pungwe | -18.45, 32.8968 | |
_ | SAIAB 200923 | 1 | Pungwe | -18.3955, 32.9707 | |
_ | SAIAB 205087 | 5 | Mutarazi | -18.5324, 32.8075 | |
_ | SAIAB 205074 | 3 | Nyamhingura | -18.3696, 32.9354 | |
_ | AC13BL04 | 3 | Pungwe | -18.3955, 32.9707 | |
Chiloglanis sp. ‘Pungwe’ | _ | AC13BL04 | 2 | Pungwe | -18.3955, 32.9707 |
_ | SAIAB 201095 | 1 | Chiyengwa | -18.6878, 32.922 | |
_ | SAIAB 201067 | 1 | Honde | -18.5992, 32.729 | |
Chiloglanis sp. ‘Nyangombe’ | _ | SAIAB 210408 | 6 | Chidya | -18.2653, 32.5903 |
Chiloglanis sp. ‘Zambezi’ | _ | SAIAB 200517 | 2 | Nyangombe | -18.0829, 32.5819 |
_ | SAIAB 81243 | 2 | Lower Zambezi | -15.656, 30.953 | |
_ | SAIAB 186643 | 1 | Okavango | -14.9397, 17.7188 | |
_ | SAIAB 186709 | 1 | Okavango | -13.5943, 16.8805 |
A total of six new COI sequences of Chiloglanis carnatus sp. nov. were generated for this study. Preparation and sequencing of genetic material was done in the Aquatic Genomics Research Platform at the NRF-SAIAB. Genomic DNA was extracted from preserved tissues using the salting-out method (
Phylogenetic analyses included genetic sequences generated from Chiloglanis carnatus sp. nov., six of the seven nominal species from southern Africa, six candidate species of Chiloglanis identified by
Four molecular species delimitation methods were used to delineate candidate species within the suckermouth catfishes of southern Africa using the same dataset used for the phylogenetic analysis. The first two methods, Automatic Barcode Gap Discovery (ABGD;
A total of 19 specimens of Chiloglanis carnatus sp. nov. collected from the Mukwadzi River were examined in the present study. Comparative material included the lectotype of C. neumanni, holotypes of six valid species from southern Africa and five candidate species identified by
Morphological characters | Abbreviation |
---|---|
Adipose fin to caudal peduncle length | AD-CPL |
Adipose-fin base length | ADFBL |
Adipose-fin height | ADFH |
Anal-fin base length | ANFBL |
Anal-fin length along longest ray | ANFL |
Anterior nare interspace | ANI |
Body depth at anus | BDA |
Body depth at dorsal-fin insertion | BDDF |
Caudal fork length | CFKL |
Caudal peduncle depth | CPD |
Caudal peduncle length | CPL |
Dorsal fin to adipose fin length | DF-ADFL |
Dorsal-fin base length | DFBL |
Dorsal-fin length along longest ray | DFL |
Dorsal-spine length | DSL |
Eye diameter (horizontal axis) | EDH |
Eye diameter (vertical axis) | EDV |
Head depth | HD |
Head length to opercular membrane margin | HL |
Lateral mandibular barbel length | LMBL |
Length of post-cleithral process | LCP |
Lower caudal-fin lobe length | LCFL |
Lower lip length | LLL |
Mandibular tooth row width | MTRW |
Maxillary barbel length | MXBL |
Medial mandibular barbel length | MMBL |
Mouth width | MW |
Occipital shield width | OSW |
Oral disc length | ODL |
Oral disc width | ODW |
Orbital interspace | OBI |
Pectoral-fin length | PFL |
Pectoral-spine length | PSL |
Pelvic-fin interspace | PVI |
Pelvic-fin length | PVFL |
Post-cleithral process to occipital shield length | CP-OSL |
Posterior nares interspace | PNI |
Pre-anal length | PANL |
Pre-dorsal length | PDL |
Pre-maxillary tooth-patch length | PMXL |
Pre-maxillary tooth-patch width | PMXW |
Pre-pectoral length | PPTL |
Pre-pelvic length | PPVL |
Snout length | SNL |
Standard length | SL |
Total length | TL |
Upper caudal-fin lobe length | UCFL |
Upper lip length | ULL |
Width at pectoral-fin insertion | WPTFI |
Abdominal vertebrae | – |
Anal fin-ray count | – |
Caudal vertebrae | – |
Dorsal fin-ray count | – |
Mandibular tooth count | – |
Pectoral fin-ray count | – |
Pelvic fin-ray count | – |
Pre-maxillary tooth count | – |
Total vertebrae | – |
Illustrations depicting linear measurements recorded from Chiloglanis specimens A lateral view B ventral view of the Oral disc C ventral view D dorsal view of the head. Abbreviations: AD-CPL-adipose fin to caudal peduncle length, ADFBL-adipose-fin base length, ADFH-adipose-fin height, ANFBL-anal-fin base length, ANFL-anal-fin length along longest ray, ANI-anterior nares interspace, BDA-body depth at anus, BDDF-body depth at dorsal-fin insertion, CFKL-caudal fork length, CPD-caudal peduncle depth, CPL-caudal peduncle length, CP-OSL- post-cleithral process to occipital shield length, DF-ADFL-dorsal fin to adipose fin length, DFBL-dorsal-fin base length, DFL-dorsal-fin length along longest ray, DSL-dorsal-spine length, EDH-eye diameter (horizontal axis), EDV-eye diameter (vertical axis), HD-head depth, HL-head length to opercular membrane margin, LCFL-Lower caudal-fin lobe length, LCP-length of post-cleithral process, LLL-lower lip length, LMBL-Lateral mandibular barbel length, MMBL-Medial mandibular barbel length, MTRW-mandibular tooth row width, MXBL-maxillary barbel length, MW-mouth width, OBI-orbital interspace, ODL-oral disc length, ODW-oral disc width, OSW-occipital shield width, PANL-pre-anal length, PDL-pre-dorsal length, PMXL-pre-maxillary tooth-patch length, PMXW- pre-maxillary tooth patch width, PNI-posterior nares interspace, PPTL-pre-pectoral length, PPVL-pre-pelvic length, PSL-pectoral-spine length, PFL-pectoral-fin length, PVFL-pelvic-fin length, PVI-pelvic-fin interspace, SL-standard length, SNL-snout length, TL-total length, UCFL–Upper caudal-fin lobe length, ULL-upper lip length, WPTFI-width at pectoral-fin insertion.
The COI alignment of 80 sequences had 534 base pairs and 176 variable sites. A total of 47 unique haplotypes were identified. Although the Bayesian phylogenetic tree was not fully resolved, it showed genetic structuring that supported the monophyly of suckermouth catfishes from southern Africa (Fig.
Ranges of cytochrome oxidase I (COI) genetic distances (%) between the Chiloglanis species included in the present study.
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | ||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Chiloglanis sp. ‘dwarf’ | 0–1.5 | |||||||||||||||
2 | Chiloglanis sp. ‘Nyangombe’ | 3.6–4.5 | 0–0.2 | ||||||||||||||
3 | Chiloglanis sp. ‘Zambezi’ | 10.7–11.4 | 9.0–9.7 | 0–0.9 | |||||||||||||
4 | Chiloglanis sp. ‘Pungwe’ | 11.0–11.8 | 9.9–10.3 | 2.1–3.0 | 0–0.2 | ||||||||||||
5 | Chiloglanis sp. ‘roughskin’ | 10.5–11.6 | 9.4–10.3 | 2.2–3.9 | 1.3–2.6 | 0–1.3 | |||||||||||
6 | Chiloglanis sp. ‘Shire’ | 11.4–11.9 | 10.1–10.3 | 5.1–5.6 | 5.0–5.2 | 4.1–5.2 | _ | ||||||||||
7 | Chiloglanis carnatus sp. nov. | 12.0–13.7 | 12.9–13.9 | 10.7–12.0 | 11.0–12.0 | 10.1–11.2 | 10.3–11.0 | 0–1.1 | |||||||||
8 | Chiloglanis anoterus | 11.0–11.4 | 11.0–11.2 | 9.5–10.1 | 9.7–10.7 | 9.6–9.9 | 9.7 | 9.7–11.4 | 0–0.2 | ||||||||
9 | Chiloglanis pretoriae | 9.9–10.3 | 10.1–10.3 | 10.7–11.0 | 10.7–10.8 | 11.0–11.4 | 10.1 | 10.7–11.4 | 3.4–3.6 | _ | |||||||
10 | Chiloglanis fasciatus | 10.9–12.0 | 12.0–12.4 | 10.9–11.4 | 11.2–11.6 | 10.3–10.9 | 10.3 | 2.8–3.9 | 9.0–9.2 | 9.6–9.7 | 0–0.6 | ||||||
11 | Chiloglanis swierstrai | 12.4–13.9 | 13.7–14.2 | 11.4–11.8 | 11.4–11.8 | 11.2–11.8 | 10.1–11.0 | 12.4–13.3 | 11.4–11.8 | 12.4–12.7 | 9.0–12.5 | 0.2–0.4 | |||||
12 | Chiloglanis bifurcus | 9.9–10.3 | 10.5–10.7 | 9.9–10.3 | 10.5–10.7 | 10.3–10.7 | 9.4 | 9.8–10.5 | 2.4–2.6 | 4.1 | 9.0–9.2 | 11.8–12.2 | 0 | ||||
13 | Chiloglanis paratus | 15.0–15.5 | 14.4–14.8 | 14.2–14.8 | 14.8–15.2 | 15.0–15.7 | 13.9–14.0 | 14.0–15.0 | 13.3–13.7 | 13.7–13.9 | 13.7–14.4 | 15.4–15.7 | 13.1–13.5 | 0.6 | |||
14 | Atopochilus savorgnani | 15.7–16.1 | 15.5–16.3 | 15.0–15.9 | 15.5–16.1 | 15.0–15.5 | 14.2–14.4 | 15.5–16.9 | 15.0–15.7 | 14.8–15.0 | 15.0–15.5 | 16.5–16.9 | 15.2–15.7 | 15.0–15.5 | 1.1 | ||
15 | Euchilichthys boulengeri | 15.2–15.4 | 15.0–15.2 | 15.2–15.4 | 14.4 | 14.0–14.2 | 14.2 | 15.4–16.1 | 14.6–15.4 | 14.8 | 15.0–15.4 | 13.7–13.9 | 14.6–15.4 | 13.3–13.5 | 11.2–11.4 | _ | |
16 | Euchilichthys royauxi | 16.5–17.0 | 16.3–16.5 | 16.3–16.9 | 15.7 | 15.4–16.1 | 14.8 | 15.7–16.5 | 16.3–16.5 | 16.5 | 15.2–15.5 | 15.4–15.5 | 16.3 | 13.5–3.9 | 10.7 | 6.6 | _ |
Bayesian inference tree of the species and lineages of the genus Chiloglanis found in southern African. The numbers at the nodes represent the Bayesian posterior probabilities. The black bars represent candidate species proposed by four molecular species delimitation methods: Automatic Barcode Gap Discovery (ABGD), Automatic Partitioning (ASAP), Bayesian implementation of the Poisson Tree Processes (bPTP), and General Mixed Yule Coalescent (GMYC).
All four molecular species delimitation methods identified Chiloglanis carnatus sp. nov., Chiloglanis sp. ‘Shire’, Chiloglanis sp. ‘Nyangombe’, C. swierstrai, C. anoterus, C. pretoriae, C. bifurcus, C. fasciatus, and C. paratus as unique molecular taxonomic units (Fig.
Principal component analysis (PCA) of the morphometric characters showed that Chiloglanis carnatus sp. nov. is separated from C. swierstrai and C. anoterus along principal component 1 (PCI) (Fig.
Summary of morphological characters examined in the present study. All values except standard length (SL) and Head length (HL) are given as percentages of the HL or SL. For the meristics the mode is given alongside the range of the counts in parentheses where the counts varied.
Species | Chiloglanis carnatus sp. nov. | Chiloglanis pretoriae | Chiloglanis anoterus | Chiloglanis bifurcus | Chiloglanis emarginatus | Chiloglanis fasciatus | Chiloglanis neumanni | Chiloglanis paratus | Chiloglanis swierstrai | Chiloglanis sp. ‘dwarf’ | Chiloglanis sp. ‘Nyangombe’ | Chiloglanis sp. ‘Pungwe’ | Chiloglanis sp. ‘roughskin’ | Chiloglanis sp. ‘Zambezi’ |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Number of specimens | 19 | 16 | 1 | 10 | 10 | 10 | 3 | 2 | 7 | 25 | 6 | 4 | 65 | 6 |
Total length | 45.3–62.2 | 31.7–67.1 | 80.1 | 68.7–84.9 | 50.2–66.6 | 37.7–53.3 | 0–42.7 | 44–51.9 | 45.2–65.7 | 31.4–51.1 | 33.1–48.2 | 34.4–62.9 | 39.8–87.6 | 55.2–62.6 |
Standard length | 35.5–48.9 | 26.5–54.6 | 61.7 | 51.4–63.9 | 40.3–55.6 | 30.3–41.7 | 33.4–39.8 | 35.8–42.4 | 34.9–51.9 | 26.0–41.6 | 26.0–38.5 | 24.6–48.6 | 31.6–66.6 | 43.7–50.6 |
Head length | 12.1–15.6 | 8.8–19.4 | 20.3 | 15.7–19.5 | 12.3–15.7 | 10.0–13.7 | 10.1–12.6 | 11.1–13.8 | 9.2–13.6 | 8.0–12.8 | 8.9–13.1 | 6.6–15.6 | 10.3–22.8 | 13.9–16.8 |
% Standard length | ||||||||||||||
Pre-pectoral length | 26.9–30.0 | 26.3–32.7 | 30.9 | 27.4–31.1 | 24.5–27.3 | 29.5–32.4 | 26.1–27.8 | 28.4–30.0 | 25.0–27.0 | 24.3–33.1 | 29.6–32.3 | 30.2–35.9 | 25.7–32.4 | 25.8–31.4 |
Pre-dorsal length | 39.9–43.7 | 40.7–48.7 | 38.6 | 38.9–42.9 | 37.7–42.7 | 40.4–44.9 | 38.6–41.5 | 39.2–42.3 | 34.5–36.7 | 36.6–50.5 | 39.0–46.8 | 35.4–44.7 | 36.0–44.1 | 36.2–46.3 |
Pre-pelvic length | 56.0–59.3 | 53.6–58.4 | 59.7 | 52.5–58.1 | 51.3–56.8 | 56.1–59.7 | 55.6–57.5 | 55.2–58.6 | 49.1–54.8 | 50.7–58.6 | 51.7–64.2 | 57.2–65.1 | 53.6–61.6 | 55.3–60.7 |
Pre-anal length | 67.6–73.3 | 66.4–72.8 | 73.3 | 63.4–69.3 | 63.0–68.2 | 67.7–73.3 | 70.7–72.4 | 67.6–71.3 | 64.1–69.5 | 64.1–75.3 | 65.2–80.1 | 56.7–80.2 | 64.3–77.6 | 58.7–76.5 |
Dorsal fin to adipose fin length | 18.2–22.6 | 18.1–25.8 | 25.5 | 21.4–29.1 | 20.2–24.4 | 21.4–24.1 | 21.6–26.9 | 23.9–28 | 18.7–26.8 | 21.5–28.6 | 20.2–28.4 | 21.9–29.1 | 19.2–30.2 | 20.5–21.6 |
Pectoral-spine length | 15.0–19.8 | 13.5–19.8 | 11.5 | 17.8–22.4 | 17.2–22 | 17.5–21.5 | 16.8–22.4 | 19.7–22.7 | 19.0–23.1 | 13.7–20 | 13.7–20.2 | 18.2–19.9 | 13.8–26.6 | 14.7–22.0 |
Pectoral-fin length | 19.3–23.6 | 14.1–22.6 | 19 | 22.9–26.6 | 19.5–24.3 | 21.4–25.1 | 21.9–24.5 | 22.6–26.4 | 23.2–25.5 | 15.4–24.3 | 18.2–21.1 | 22.1–25.9 | 17.6–27.4 | 20.5–26.1 |
Width at pectoral-fin insertion | 23.0–25.3 | 24.4–29.8 | 24.3 | 24.7–27.9 | 23.9–26.5 | 23.7–26.1 | 21.4–24.9 | 23.8–25.8 | 17.6–21.5 | 21.7–25.7 | 22.3–26.1 | 23.9–27.0 | 21.0–27.6 | 23.6–25.7 |
Pelvic-fin length | 10.8–14.2 | 12.2–15.9 | 12.9 | 14.6–17.2 | 10.8–14.6 | 11.6–14.6 | 13.6–14 | 13.0–13.1 | 12.3–15.4 | 11.7–15.3 | 11.7–13.3 | 13.8–16.0 | 10.2–17.5 | 13.4–15.7 |
Pelvic-fin interspace | 3.0–5.1 | 2.1–4.7 | 4.3 | 4.4–6.2 | 2.8–4.7 | 2.5–4.7 | 3.0–3.9 | 4.4–4.7 | 2.7–4.9 | 1.8–6.0 | 2.0–4.2 | 2.7–5.4 | 2.6–8.2 | 3.8–5.0 |
Body depth at dorsal-fin insertion | 15.5–20.7 | 16.0–21.0 | 19.1 | 16.2–21.8 | 17.3–22.4 | 15.4–19.3 | 17.7–22.1 | 15.2–18.1 | 12.2–19.2 | 16.8–22.7 | 15.7–19.3 | 17.2–20.8 | 17.2–25.3 | 17.3–20.2 |
Body depth at anus | 13.9–17.6 | 15.3–18.7 | 18 | 16.7–21.2 | 15.5–18.6 | 11.9–14.5 | 13.5–16.1 | 12.9–15.4 | 11.3–14.6 | 14.3–19.9 | 13.1–16.2 | 13.8–17.8 | 12.5–20.4 | 14.0–15.6 |
Dorsal-spine length | 13.2–18.0 | 13.3–20.9 | 11.3 | 13–17.5 | 14.0–17.4 | 15.8–20.5 | 17.1–20.4 | 18.4–21.3 | 14.0–15.0 | 11.6–20.1 | 14.5–17.9 | 13.8–20.6 | 12.5–25.4 | 11.9–17.8 |
Dorsal-fin base length | 10.7–14.1 | 12.8–18.0 | 8.6 | 9.5–13.2 | 8.8–12.9 | 10.4–13.7 | 8.5–10.2 | 12.8–14.6 | 7.5–9.6 | 11.5–23.7 | 12.8–16.6 | 20.6–28 | 11.8–30.6 | 15.4–24.7 |
Adipose fin to caudal peduncle length | 12.9–17.0 | 13.3–17.7 | 15.2 | 14.9–18.5 | 13.1–17.0 | 13.1–16.8 | 11.9–14.1 | 13.6–15.6 | 14.0–15.9 | 14.4–19.8 | 15.1–20.9 | 11.3–16.1 | 13.3–21.6 | 15.7–17.2 |
Adipose-fin base length | 17.0–23.3 | 16.2–25.2 | 16.5 | 9.2–13.6 | 14.6–19.6 | 12.4–17.8 | 15.5–17.4 | 13.7–15.4 | 17.0–22.5 | 13.2–17 | 11.3–17.3 | 13.2–19.6 | 10.4–19.3 | 14.9–17.4 |
Adipose-fin height | 4.1–6.8 | 4.2–5.8 | 3.5 | 2.9–4.6 | 2.3–5.0 | 3.3–5.2 | 2.7–3.1 | 3.0–3.9 | 3.5–5.2 | 2.8–5.4 | 3.2–5.3 | 3.3–5.6 | 3.3–8.7 | 5.0–6.2 |
Anal-fin length along longest ray | 11.7–17.9 | 13.7–18.3 | 15.5 | 14.1–17.8 | 11.6–14.6 | 11.5–16.6 | 19.2–20.9 | 12.8–14.6 | 10.1–15.5 | 11.8–18.7 | 13.0–17.2 | 11.0–17.5 | 10.9–20.5 | 13.2–16.9 |
Anal-fin base length | 10.5–13.5 | 11.7–15.4 | 12.9 | 11.5–15.3 | 10.9–14.9 | 8.9–11.4 | 11.1–12.1 | 10.6–11.0 | 11.7–15 | 10.6–16.4 | 11.9–15.5 | 11.3–19.4 | 8.2–15.6 | 11.8–14.2 |
Caudal peduncle depth | 11.3–13.2 | 11–13.8 | 12.2 | 11.1–14.1 | 10.2–11.9 | 7.5–8.8 | 9.5–9.9 | 9.6–9.9 | 7.2–8.7 | 10.9–12.6 | 10.0–11.9 | 9.6–12.8 | 9.8–14.9 | 10.0–11.1 |
Caudal peduncle length | 15.9–19.7 | 15.8–22.6 | 18.6 | 19.9–22.7 | 19.1–23.7 | 18.8–21.7 | 16.0–18.8 | 17.7–18.9 | 19.6–22.0 | 17.4–24.5 | 20.3–22.9 | 13.6–15.8 | 13.9–21.9 | 16.2–17.9 |
Head length | 30.5–34.9 | 33.3–38.6 | 32.9 | 29.5–31.3 | 26.5–30.7 | 30.4–35.2 | 30.2–31.7 | 31.0–32.6 | 24.8–28.0 | 27.8–34.9 | 32.8–39.4 | 25.9–33.7 | 28.3–36.3 | 31.4–34.1 |
% Head length | ||||||||||||||
Eye diameter (vertical axis) | 9.9–13.8 | 11.6–18.3 | 10.6 | 12.1–16.6 | 11.9–16.5 | 9.4–13.1 | 9.1–14.9 | 10.6–12.5 | 13.2–18.6 | 11.8–16.1 | 12.6–13.9 | 10.9–20.4 | 7.4–15.3 | 11.5–15.1 |
Orbital interspace | 21.5–28.7 | 22.6–28.9 | 23.4 | 19.5–24.6 | 18.3–24.4 | 18.5–25.4 | 25.7–30.2 | 22.2–23.9 | 15.3–22.7 | 23.3–38.5 | 20.9–25.2 | 23.8–38.4 | 18.0–38.9 | 22.7–30.4 |
Anterior nares interspace | 9.5–15.5 | 12.4–16.6 | 11.9 | 19.5–21.2 | 16.5–22.4 | 11.5–17.6 | 13.9–19.8 | 13.3–15.5 | 15.7–22.4 | 10.9–18.4 | 13.0–14.7 | 13.7–23.0 | 11.0–21.6 | 13.5–16.7 |
Posterior nares interspace | 10.3–15.5 | 11–15.5 | 11.8 | 15.3–21.9 | 13.8–20.9 | 9.9–16.1 | 14.9–22.2 | 9.3–10.9 | 12.6–18.2 | 12.9–16.7 | 12.6–14.7 | 8.9–13.0 | 7.5–18.4 | 10.2–13.0 |
Snout length | 54.0–66.2 | 55.7–65.7 | 65 | 58.2–64.8 | 49.5–59.9 | 58.9–69.3 | 51.5–56.2 | 56.9–59.0 | 51.5–57.5 | 52.3–66.1 | 51.4–67.3 | 54.7–84 | 51.1–68.0 | 53.4–66.2 |
Pre-maxillary tooth-patch length | 8.2–12.3 | 8.2–13.9 | 11.7 | 7.0–9.3 | 6.3–8.2 | 7.5–9.5 | 9.9–12.9 | 9.2–11.8 | 8.5–11.6 | 6.8–10.3 | 6.1–9.9 | 7.5–11.5 | 5.4–14.3 | 9.9–12.1 |
Pre-maxillary tooth-patch width | 36.8–47.9 | 30.7–46.8 | 51.5 | 44.1–50.2 | 39.9–46.2 | 40.3–46.7 | 36.4–38.9 | 41.3–44.2 | 39.5–47.1 | 35.9–45.3 | 39.6–47.8 | 31.7–44.5 | 29.7–50.1 | 37.2–45.1 |
Mandibular tooth row width | 4.6–8.1 | 16.0–25.6 | 10.5 | 10.4–17.3 | 9.6–13.5 | 4.8–6.6 | 9.9–13.5 | 7.2–7.7 | 10.0–16.6 | 13.6–25.0 | 19.0–25.5 | 17.6–27.8 | 11.9–22.2 | 20.5–25.4 |
Maxillary barbel length | 20.3–28.8 | 21.3–36.8 | 22.7 | 23.8–41.8 | 29.1–41.8 | 26.4–31.2 | 21.8–30.2 | 24.3–27.5 | 44.2–66.8 | 17.4–34.3 | 20.1–28.1 | 19.7–32.1 | 20.2–45.7 | 31.3–37.0 |
Upper lip length | 11.1–16.2 | 11.7–18.8 | 16.7 | 8.4–12.3 | 6.6–10.6 | 8.8–15.5 | 9.1–10.0 | 12.3–12.4 | 7.0–10.5 | 6.9–14.3 | 8.4–13.5 | 11.3–19.5 | 10.2–19.5 | 12.5–17.2 |
Lower lip length | 18.3–26.6 | 22.4–27.7 | 25.1 | 17.7–25.6 | 23.5–28.8 | 18.8–24.9 | 19.8–27.0 | 22.8–27.6 | 19.2–26.0 | 12.6–22.9 | 20.7–29.3 | 19.7–27.8 | 9.6–16.8 | 20.7–24.7 |
Mouth width | 23.9–33.8 | 24.8–32.6 | 39.6 | 30.9–39.1 | 25.7–36.2 | 25.6–32.1 | 20.6–22.8 | 28.0–35.9 | 27.9–34.0 | 20.4–33.4 | 27.1–33.8 | 25.2–37.8 | 17.5–32.8 | 24.7–31.1 |
Oral disc width | 51.1–64.6 | 48.4–70.3 | 69.1 | 59.3–69.3 | 58.9–66.3 | 51.4–64.1 | 47.6–53.5 | 60.8–64.8 | 51.8–63.0 | 44.4–57.3 | 45.8–56.1 | 63.4–69.7 | 35.7–69.2 | 54.4–63.3 |
Oral disc length | 48.6–57 | 46.0–61.1 | 63.8 | 53.7–61.3 | 43.3–54.7 | 48.4–59.7 | 41.6–53.2 | 55.7–57.8 | 48.6–62.4 | 40.7–53.9 | 41.9–58.2 | 46.5–57.4 | 38.6–57.1 | 47.9–57.3 |
Meristics | ||||||||||||||
Mandibular tooth count | 10 | 12 | 12 | 8 | 8 (6–8) | 8 | 8 | 12 | 11 (11–14) | _ | _ | _ | _ | _ |
Pre-maxillary tooth count | 60 (43–69) | 51–59 | 86 | 54 (50–64) | 36–54 | 64 (51–65) | 55–60 | 39–51 | 50 (34–59) | _ | _ | _ | _ | _ |
Pectoral-fin ray count | 8 (6–8) | 8 | 8 | 8 (7–8) | 7 | 8 | 8 | 8 | 8 | _ | _ | _ | _ | _ |
Pelvic-fin ray count | 7 (6–7) | 7 | 7 | 7 | 7 (7–8) | 7 | 7 | 7 | 7 | _ | _ | _ | _ | _ |
Dorsal-fin ray count | 6 (5–7) | 6 | 5 | 5 (5–6) | 6 (5–6) | 6 (5–6) | 5 | 5 | 5 (5–6) | _ | _ | _ | _ | _ |
Anal-fin ray count | 12 (12–13) | 10 | 13 | 12 (9–13) | 10 (10–12) | 9 (8–12) | 10 (10–12) | 9 | 12 (9–13) | _ | _ | _ | _ | _ |
X-rays | ||||||||||||||
Number of specimens | 9 | 2 | 1 | 4 | 6 | 7 | 5 | 1 | 6 | _ | _ | _ | _ | _ |
Abdominal vertebrae | 13 (11–13) | 12–13 | 13 | 11 (10–11) | 10 (10–12) | 13 (12–13) | 13 (12–13) | 12 | 12 (11–13) | _ | _ | _ | _ | _ |
Caudal vertebrae | 17 (16–18) | 18–19 | 17 | 20 (18–20) | 19 (17–19) | 16 (16–17) | 16 (16–18) | 16 | 20 (16–20) | _ | _ | _ | _ | _ |
Total vertebrae | 29 (29–30) | 28 | 30 | 30 (29–30) | 29 (28–30) | 29 (28–29) | 28 | 27 | 32 (31–32) | _ | _ | _ | _ | _ |
The PCA loadings for the first two principal components for the measured characters of Chiloglanis species and lineages from southern Africa.
Principal component | 1 | 2 |
---|---|---|
Eigenvalue | 90.91 | 70.84 |
% variance | 22.46 | 17.50 |
Adipose fin to caudal peduncle length | -0.02 | -0.02 |
Adipose-fin base length | 0.05 | -0.01 |
Adipose-fin height | -0.04 | 0.00 |
Anal-fin base length | 0.03 | -0.05 |
Anal-fin length along longest ray | -0.03 | -0.06 |
Body depth at anus | -0.02 | -0.04 |
Body depth at dorsal-fin insertion | -0.09 | -0.06 |
Caudal peduncle depth | -0.05 | -0.02 |
Caudal peduncle length | 0.08 | -0.10 |
Dorsal-fin to adipose fin length | -0.02 | -0.02 |
Dorsal-fin base length | -0.17 | 0.08 |
Dorsal-spine length | -0.06 | 0.04 |
Pre-anal length | -0.16 | 0.17 |
Pre-dorsal length | -0.10 | 0.11 |
Pre-pectoral length | -0.08 | 0.10 |
Pre-pelvic length | -0.12 | 0.15 |
Pectoral-spine length | 0.04 | 0.01 |
Pectoral-fin length | 0.04 | 0.03 |
Pelvic-fin length | 0.00 | 0.02 |
Width at pectoral-fin insertion | -0.04 | 0.06 |
Pelvic-fin interspace | 0.00 | 0.02 |
Head length | -0.18 | 0.07 |
Anterior nares interspace | 0.14 | -0.08 |
Eye diameter (vertical axis) | 0.11 | -0.03 |
Lower lip length | 0.02 | 0.37 |
Mandibular tooth row width | -0.16 | -0.05 |
Maxillary barbel length | 0.60 | -0.41 |
Mouth width | 0.35 | 0.21 |
Orbital interspace | -0.18 | -0.14 |
Oral disc length | 0.22 | 0.34 |
Oral disc width | 0.39 | 0.41 |
Pre-maxillary tooth-patch length | 0.00 | 0.09 |
Pre-maxillary tooth-patch width | 0.23 | 0.24 |
Posterior nares interspace | 0.13 | -0.13 |
Snout length | -0.05 | 0.35 |
Upper lip length | -0.09 | 0.15 |
Summary of morphological characters for Chiloglanis carnatus sp. nov. All values except standard length (SL) and Head length (HL) are given as percentages of the HL or SL.
Holotype | Paratypes | ||||
---|---|---|---|---|---|
Male | Males | Females | |||
Number of specimens | 7 | 11 | |||
Range | Mean | Range | Mean | ||
Total length | 58.2 | 45.3–62.2 | 49.8 | 45.3–56.1 | 52.2 |
Standard length | 46.8 | 36.5–48.9 | 39.6 | 35.5–45.5 | 41.8 |
Head length | 14.3 | 12.1–15.1 | 13.0 | 12.3–15.6 | 13.5 |
% Standard length | |||||
Pre-pectoral length | 28.1 | 26.9–30.0 | 28.9 | 27.1–29.1 | 28.3 |
Pre-dorsal length | 40.2 | 40.0–42.6 | 41.6 | 39.9–43.7 | 41.3 |
Pre-pelvic length | 58.4 | 56.0–58.8 | 57.8 | 56.9–59.3 | 57.9 |
Pre-anal length | 71.1 | 67.6–70.8 | 69.1 | 67.9–73.3 | 70.6 |
Dorsal fin to adipose fin length | 20.9 | 18.4–22.2 | 20.6 | 18.2–22.6 | 20.6 |
Pectoral-spine length | 18.6 | 15.6–19.8 | 17.7 | 15.0–18.6 | 16.5 |
Pectoral-fin length | 20.9 | 20.9–23.6 | 22.4 | 19.3–22.2 | 20.9 |
Width at pectoral-fin insertion | 23.8 | 23.3–25.2 | 24.3 | 23.0–25.3 | 24.3 |
Pelvic-fin length | 12.2 | 13.3–14.2 | 13.7 | 10.8–14.1 | 12.3 |
Pelvic-fin interspace | 4.6 | 3.3–4.6 | 4.0 | 3.0–5.1 | 3.9 |
Body depth at dorsal-fin insertion | 18.9 | 15.5–20.7 | 18.0 | 16.2–20.1 | 17.8 |
Body depth at anus | 17.6 | 15.3–16.9 | 15.8 | 13.9–17.0 | 15.9 |
Dorsal-spine length | 15.7 | 13.6–18.0 | 16.1 | 13.2–17.7 | 15.9 |
Dorsal-fin length along longest ray | 17.9 | 15.2–20.7 | 18.5 | 16.2–20.0 | 17.4 |
Dorsal-fin base length | 11.0 | 12.1–14.1 | 13.1 | 10.7–13.8 | 12.3 |
Adipose fin to caudal peduncle length | 13.5 | 12.9–17.0 | 15.0 | 10.3–16.4 | 13.8 |
Adipose-fin base length | 22.3 | 17.0–22.0 | 19.6 | 17.2–23.3 | 19.8 |
Adipose-fin height | 5.1 | 4.1–6.1 | 5.2 | 4.2–6.8 | 5.3 |
Anal-fin length along longest ray | 14.2 | 13.1–17.2 | 15.7 | 11.7–17.9 | 13.4 |
Anal-fin base length | 12.1 | 11.8–15.3 | 13.2 | 11.1–13.4 | 12.5 |
Caudal peduncle depth | 12.2 | 11.3–13.2 | 12.1 | 11.4–13.1 | 12.1 |
Caudal peduncle length | 16.8 | 16.0–19.2 | 18.3 | 15.9–19.7 | 17.5 |
Caudal fork length | 12.3 | 9.8–14.5 | 11.4 | 9.2–14.4 | 11.7 |
Head length | 30.6 | 30.9–34.8 | 32.9 | 30.5–34.9 | 32.2 |
% Head length | |||||
Head depth | 57.4 | 43.9–57.6 | 51.2 | 48.2–57.3 | 51.2 |
Eye diameter (vertical axis) | 11.9 | 10.6–13.2 | 11.7 | 9.9–13.8 | 11.9 |
Eye diameter (horizontal axis) | 15.7 | 13.0–16.4 | 14.1 | 12.9–16.8 | 15.0 |
Orbital interspace | 25.1 | 22.3–28.7 | 24.1 | 21.5–26.8 | 24.5 |
Anterior nares interspace | 12.1 | 9.5–15.5 | 12.1 | 10.4–14.6 | 12.2 |
Posterior nares interspace | 12.6 | 11.0–15.5 | 13.5 | 10.3–15.4 | 12.7 |
Snout length | 61.1 | 54.3–63.8 | 58.7 | 54.0–66.2 | 60.7 |
Pre-maxillary tooth-patch length | 9.9 | 8.2–11.0 | 9.9 | 8.8–12.3 | 10.4 |
Pre-maxillary tooth-patch width | 44.3 | 36.8–44.7 | 41.1 | 38.4–47.9 | 42.1 |
Mandibular tooth row width | 6.7 | 4.6–8.1 | 6.4 | 5.4–7.1 | 6.4 |
Maxillary barbel length | 27.6 | 20.3–27.2 | 25 | 22.3–28.8 | 25.3 |
Upper lip length | 15.1 | 11.1–14.5 | 13.1 | 11.3–16.2 | 13.9 |
Lower lip length | 23.4 | 18.3–25.2 | 22.7 | 20.7–26.6 | 23.8 |
Mouth width | 29.2 | 25.3–30.8 | 27.3 | 23.9–33.8 | 28.1 |
Oral disc width | 62.8 | 51.1–62.9 | 57.2 | 52.9–64.6 | 58.2 |
Oral disc length | 54.3 | 48.6–57.0 | 53.1 | 50.2–56.4 | 53.3 |
Postcleithral process to occipital shield | 37.8 | 29.5–36.3 | 33.1 | 32.2–38.3 | 35.5 |
Length of postcleithral process | 29.6 | 23.4–28.9 | 25.5 | 22.9–27.8 | 25.9 |
Occipital shield width | 23.6 | 14.6–19.5 | 16.9 | 14.9–24.2 | 18.8 |
Lower caudal-fin lobe length | 13.4 | 9.3–13.0 | 10.6 | 10.0–12.7 | 11.2 |
Upper caudal-fin lobe length | 10.8 | 8.7–12.1 | 9.8 | 9.1–11.7 | 10.4 |
Medial mandibular barbel length | 0.6 | 0.2–0.6 | 0.4 | 0.4–0.9 | 0.6 |
Lateral mandibular barbel length | 1.3 | 1.0–1.8 | 1.4 | 1.1–1.8 | 1.4 |
Meristics | Range | Mode | Range | Mode | |
Mandibular tooth count | 10 | 8–10 | 10 | 8–10 | 10 |
Pre-maxillary tooth count | 59 | 43–69 | _ | 49–68 | 60 |
Pectoral fin-ray count | 8 | 7–8 | 8 | 6–8 | 8 |
Pelvic fin-ray count | 7 | 7 | 7 | 6–7 | 7 |
Dorsal fin-ray count | 6 | 6 | 6 | 5–7 | 6 |
Anal fin-ray count | 13 | 12–13 | 12 | 12–13 | 12 |
Abdominal vertebrae | 12 | 12 | _ | 11–13 | 13 |
Caudal vertebrae | 17 | 17 | _ | 16–18 | 16 |
Total vertebrae | 29 | 29 | _ | 29–30 | 29 |
Scatterplots of the morphometric characters of the Chiloglanis species and lineages from southern African. Key: Chiloglanis carnatus sp. nov. (red circle), C. pretoriae (brown triangle), C. swierstrai (dark green square), C. bifurcus (purple right-pointing triangle), C. anoterus (green heavy asterisk), C. paratus (pink diamond), C. emarginatus (Blue pentagon), C. fasciatus (grey star), C. neumanni (light blue circle), Chiloglanis sp. ‘dwarf’ (orange eight spoked asterisk), Chiloglanis sp. ‘roughskin’ (yellow multiplication sign), Chiloglanis sp. ‘Pungwe’ (black plus sign), Chiloglanis sp. ‘Zambezi’ (blue down-pointing hollow triangle), Chiloglanis sp. ‘Nyangombe’ (light blue hollow circle).
Additional scatterplots were generated to explore the characters that further distinguish the Chiloglanis carnatus sp. nov. specimens. The Chiloglanis carnatus sp. nov. specimens have a narrower mandibular tooth row width (4.6–8.1%HL) compared to C. pretoriae (16.0–25.6%HL), C. swierstrai (10.0–16.6%HL), C. neumanni (9.9–13.5%HL), C. emarginatus (9.6–13.5%HL), C. bifurcus (10.4–17.3%HL), C. anoterus (10.5%HL), Chiloglanis sp. ‘dwarf’ (13.6–25.0%HL), Chiloglanis sp. ‘Nyangombe’ (19.0–25.5%HL), Chiloglanis sp. ‘Pungwe’ (17.6–27.8%HL), Chiloglanis sp. ‘roughskin’ (11.9–22.2%HL), and Chiloglanis sp. ‘Zambezi’ (20.5–25.4%HL; Fig.
Comparison of meristic characters revealed consistent differences between Chiloglanis carnatus sp. nov. specimens and the other species from southern Africa. Chiloglanis carnatus sp. nov. specimens have ten closely packed mandibular teeth that separate them from C. bifurcus, C. emarginatus, C. fasciatus, and C. neumanni that have eight mandibular teeth as well as from C. anoterus, C. pretoriae, C. paratus, and C. swierstrai that have > 10 mandibular teeth (Fig.
The integrated approach used in this study provided genetic and morphological characters that clearly and consistently distinguish Chiloglanis carnatus sp. nov. from the known species and lineages from this region. This study has thus provided evidence that supports the description of the Chiloglanis carnatus sp. nov. as a new species.
Holotype. Zimbabwe • ♂, stored in 70% ethanol, 46.8 mm SL, Fig.
Chiloglanis carnatus sp. nov. is readily distinguished from its congeners in southern Africa (i.e. C. anoterus, C. bifurcus, C. emarginatus, C. fasciatus, C. paratus, C. pretoriae and C. swierstrai) by the presence of a dorsal fin that has a basal portion covered by a fleshy skin, a character which is absent in the other species. Chiloglanis carnatus possesses ten closely packed mandibular teeth, that further distinguishes it from C. fasciatus that has eight closely packed mandibular teeth; C. bifurcus and C. emarginatus that have eight widely spaced mandibular teeth; C. anoterus, C. paratus, and C. pretoriae that have 12 closely packed mandibular teeth; and C. swierstrai that has 14 closely packed mandibular teeth. Chiloglanis carnatus possesses a deeply forked caudal fin that readily separates it from C. pretoriae and C. emarginatus that have emarginate caudal fins, and from C. anoterus that has a caudal fin with extended median rays in males and emarginate in females. Chiloglanis carnatus possesses a caudal fin with an upper lobe that is shorter than the lower lobe. This distinguishes it from C. bifurcus that has a caudal fin with an upper lobe that is longer than the lower lobe. Chiloglanis carnatus has an oral disc with a well-developed mid-ventral cleft that distinguishes it from C. swierstrai that possesses an oral disc without a mid-ventral cleft. Chiloglanis carnatus possesses a smooth skin with a few tubercles occasionally found on the head that separates it from C. fasciatus that has its entire dorsal and lateral body surfaces mostly covered by small tubercles. Chiloglanis carnatus has a dorsal spine with crenate anterior and posterior margins that distinguish it from C. paratus that has a dorsal spine with a serrated posterior margin.
Morphometric proportions and meristics are summarised in Table
Body shape. Anterior portion of body slightly compressed dorsally, becoming laterally compressed from pelvic fin insertion to caudal peduncle. Body greatest depth at dorsal-fin insertion. Pre-dorsal profile convex, sharply slopping from snout to posterior nostril, gently from nostril to dorsal-fin origin. Post-dorsal profile about straight from dorsal-fin base to adipose-fin origin, becoming gently concave from adipose-fin origin to caudal fin. Ventral profile gently convex from region just posterior to oral disc to anal-fin origin, becoming gently concave from anal-fin origin to caudal fin.
Head. slightly depressed dorsally. Oval eye dorsally positioned, ~ 1/2 distance between snout and gill opening. Interorbital distance greater than distance between nostrils. Anterior and posterior nostrils closer to the eye than snout. Distance between anterior nostrils slightly greater than distance between posterior nostrils. Posterior nostril medially positioned relative to orbit. Anterior nostril with posterior flap; posterior nostril with anterior flap. Occipital-nuchal shield not visible through skin. Gill opening above pectoral fin insertion.
Oral disc. Mouth inferior; large upper and lower lips combined to form oral disc (see Fig.
Dentation. Pre-maxillary teeth arranged in three or four rows; variable number of teeth (43–69). Up to 5+5 closely packed mandibular teeth; central teeth projecting higher than outer teeth forming a gentle arc; replacement tooth row emerges anteriorly to the functional row.
Fins. Dorsal-fin ray count 5–7 (6), originating in anterior 1/3 of body, posterior to pectoral-fin origin. Dorsal fin basal portion covered by a fleshy skin prominent in large adult males and females with ~ ¾ of the dorsal spine and the first two rays also covered by fleshy skin (Fig.
Comparison of the dorsal and adipose fins of Chiloglanis carnatus sp. nov. and the type specimens of the valid southern African species A Chiloglanis carnatus sp. nov. (SAIAB 236631) specimens have an extended dermal tissue covering the base of the dorsal fin that distinguishes them from B C. swierstrai (SAIAB 186247) C C. bifurcus (SAIAB 120160) D C. emarginatus (SAIAB 120117) E C. fasciatus (SAIAB 204928) F C. paratus (SAIAB 186248) G C. pretoriae (SAIAB 30011) H C. anoterus (SAIAB 186246). Scale bars: 1 cm.
Skin. Skin smooth with occasional tubercles present, concentrated on dorsal and lateral surface of head. Lateral line complete; originating anterior to dorsal fin at same horizontal level of orbit and sloping ventrally until it lies mid-laterally along body.
Sexual dimorphism. Urogenital opening situated adjacent to origin of anal fin. Urogenital papillae sexually dimorphic; elongated in males; reduced and separated from anus by shallow invagination in females.
Colouration. Overall body background colouration brown with yellowish ventral surface. Anterior portion of body dark brown becoming paler towards posterior. Small dark melanophores scattered across entire dorsal and lateral sides. Six yellowish brown blotches on lateral surface of body; two vertically arranged posterior to end of adipose fin; one above origin of anal fin; two above pelvic fin origin; and one below dorsal fin origin. Basal 1/3 of fins pale to dark brown with medium and posterior portion of fins gradually becoming translucent. Dark blotch cuts vertically across caudal peduncle lobes.
Vertebral counts. Total vertebrae 29 or 30 (29), abdominal vertebrae 11–13 (12), caudal vertebrae 16–18 (17).
The specific epithet carnatus means fleshy, referring to the dermal tissue covering the base of the dorsal fin of some of the larger specimens of this species and the general robust body structure of this species compared to its regional congeners.
Chiloglanis carnatus was collected from two sites in the Mukwadzi River near the bridge on the Mutorashanga Road. The Mukwadzi River is a perennial river that originates from wetlands (dambos) on the eastern side of the Great Dyke. This river flows in a north-western direction cutting through the Great Dyke before it joins the Manyame River. The Great Dyke is a major intrusion of mafic and ultramafic rocks that have vast ore deposits, including gold, silver, chromium, platinum, nickel, and asbestos. The rich mineral deposits have resulted in the establishment of many mines along the Great Dyke. The sites where C. carnatus was collected were in a communal area surrounded by rural communities on the western slope of the Great Dyke. The substratum at the sites was composed of bedrock, cobbles and gravel, and the riparian vegetation was dominated by Syzygium Gaertner, 1788 and Phragmites Adanson, 1763. At these sites C. carnatus co-occurred with native fish species that include Labeo cylindricus Peters, 1852, Opsaridium zambezense (Peters, 1852), Enteromius trimaculatus (Peters, 1852), Tilapia sparrmanii Smith, 1840, Clarias gariepinus (Burchell, 1822), and Labeobarbus marequensis (Smith, 1841) as well as the non-native species Serranochromis jallae (Boulenger, 1896) and Micropterus salmoides (Lacepède, 1802).
This study integrated molecular and morphological data to evaluate the taxonomic distinctiveness of specimens of suckermouth catfishes that were collected from the middle Zambezi River system in Zimbabwe. Based on substantial genetic differentiation as well as consistent meristic, morphometric, and qualitative differences from its southern African congers, a new species of Chiloglanis is described. This is the first description more than five decades after the last comprehensive review of Chiloglanis species from southern Africa (see
The dentition of species in the genus Chiloglanis, like that of most members of the family Mochokidae, is highly specialised (
Rheophilic habitats form ‘islands’ with suitable environmental conditions for specialised taxa such as those in the genus Chiloglanis. The disjunct distribution of these habitats within a river may play an important role in promoting genetic and morphological diversity within rheophilic taxa. Some rheophilic species have very narrow distribution ranges such that significant differences have been found in the fish communities occurring at different rapids within the same river system (
A number of southern African freshwater fish species in the genera Enteromius Cope, 1867, Nothobranchius Peters, 1868, Pseudobarbus Smith, 1841, Sandelia Castelnau, 1861, Galaxias Cuvier, 1816, and Oreochromis Günther, 1889 are threatened with extinction due to their narrow geographic ranges, the introduction of invasive species, and habitat degradation (
The description of C. carnatus contributes towards clarifying the taxonomic uncertainty surrounding species of the genus Chiloglanis found within the geographic range formerly attributed to C. neumanni within southern Africa. The discovery of C. carnatus follows the common pattern found among recent taxonomic studies within the region whereby comprehensive sampling across poorly explored regions and the use of integrated taxonomic approaches has identified unique diversity within species previously thought to have wide distribution ranges (
We would like to thank the NRF-SAIAB personnel including Paul Skelton, Roger Bills, Maditaba Meltaf, Nkosinathi Mazungula, Nonkoliso Mgibntaka, Amanda Gura, Zinzi Somana, Siphamandla Mceleli, Gwynneth Matcher, and Taryn Bodil for the support during this study.
The authors have declared that no competing interests exist.
Ethical clearance for the approaches used for sample collection and processing was approved by the National Research Foundation-South African Institute for Aquatic Biodiversity (NRF-SAIAB) Animal Ethics Committee (Ref#: 2014/03 and REF#: 25/4/1/7/5_2022-02).
This research was supported by the Rhodes University Sandisa Imbewu Grant, the NRF-Research Development Grant (CSRP190416431023), NRF-SAIAB Refresh project (FBIP-211006643719) and NRF-SAIAB Topotypes project (IBIP-BS 13100251309).
Conceptualization: WK, PB, TB, AC. Data curation: TIM. Formal analysis: TIM. Funding acquisition: WK, AC. Investigation: TIM. Methodology: PB, AC, WK, TIM. Project administration: AC, WK. Resources: AC, TB. Supervision: AC, WK, PB. Visualization: PB, TIM. Writing – original draft: TIM. Writing – review and editing: TIM, PB, AC, TB, WK.
Tadiwa I. Mutizwa https://orcid.org/0000-0003-4017-1720
Wilbert T. Kadye https://orcid.org/0000-0002-5273-8360
Pedro H. N. Bragança https://orcid.org/0000-0002-8357-7010
Taurai Bere https://orcid.org/0000-0002-8603-5137
Albert Chakona https://orcid.org/0000-0001-6844-7501
All of the data that support the findings of this study are available in the main text.