Corresponding author: Nasreen Peer (
Academic editor: Célio Magalhães
A new species of freshwater crab,
Peer N, Gouws G, Maliwa L, Barker N, Juby P, Perissinotto R (2023) Description of a new montane freshwater crab (Arthropoda, Malacostraca, Decapoda, Potamonautidae) from the Eastern Cape, South Africa. ZooKeys 1160: 89–108.
In South Africa, the genera
Recently, several new species have been described from natural forest habitats (
Aside from high forest biodiversity, the Amathole Mountain Range, forming part of the escarpment between the Sneeuberg range in the west and the Drakensberg range in the east, is considered to display great diversity across habitat types, as well as high levels of endemism in terms of flora (
In this paper, we describe
Crabs were collected from three localities (Table
Map showing the location of the Amathole Mountain Range sampling sites (black markers) in relation to nearby towns and villages (white points). South Africa National Land Cover (SANLC) 2018 map layer shows land cover to be predominantly indigenous forest and plantations with residential area nearby.
Localities of the three sample sites.
Site name | Coordinates |
---|---|
Katberg State Forest |
|
Hogsback Arboretum |
|
Hogsback Waterfall |
|
Crabs were collected by hand or net and preserved in 70% ethanol.
The genetic placement and relationships of the proposed new species were examined using data generated in two sequential studies.
For the first study, total genomic DNA was extracted from 0.5–1 mg of pereiopod muscle tissue from specimens collected from Hogsback and Katberg during 2013. Tissue was rinsed in sterile water and DNA was extracted using an Invisorb Spin Tissue Mini Kit (Invitek Molecular, Berlin), following the manufacturer’s protocol.
A fragment of the large ribosomal subunit 16S mitochondrial marker was amplified by Polymerase Chain Reaction, using the primers of
In the second study, DNA was extracted from specimens collected from Hogsback during 2018, using a PureLink Miniprep kit (Invitrogen, Carlsbad, California). A fragment of the protein-coding mtDNA cytochrome
Data sets for each of the 16S and COI fragments included data generated in the present study and published data for all described southern African
ClustalX2 (
Morphological variables were measured using a pair of Vernier callipers. A Canon Powershot G12 digital camera was used to photograph carapaces and appendages, while a Nikon SMZ25 microscope fitted with a Nikon Digital Sight DS-Fi2 camera was used for macro-examination and to take photos of gonopods and mouthparts.
Abbreviations for all morphological and morphometric characters (following
New sequences generated in the present study were lodged in GenBank (16S: accession numbers
The most likely topology (-lnL = 3754.743) obtained in the Maximum-Likelihood analysis of a 549 nucleotide 16S rRNA alignment, depicting relationships between potamonautid freshwater crabs sampled from Hogsback and Katberg (Eastern Cape, South Africa) and known southern African
The COI alignment was 660 nucleotides in length. The optimal model had base frequencies of A = 0.292, C = 0.184, G = 0.154 and T = 0.371, a rate matrix of RA↔C = 4.203, RA↔G = 10.249, RA↔T = 2.385, RC↔G = RG↔T = 1.000, RC↔T = 31.047, a proportion of invariant sites (I = 0.549) and a gamma distribution of rate variation (α = 1.280). The tree produced by the
The most likely topology (-lnL = 5093.453) obtained in the Maximum-Likelihood analysis of a 660 nucleotide mtDNA cytochrome
The topologies produced by the analyses of the 16S and COI data were congruent with respect to, and reflected, the major phylogenetic divisions reported previously for the southern African
Of relevance to the current study, the crabs sampled from Hogsback and Katberg were placed in two separate clades. In the 16S topology, samples from Hogsback and Katberg were placed within the clade of small-bodied, mountain-dwelling species, sister to
Uncorrected sequence divergences among individuals are presented in Suppl. material
For the COI data, where the only specimens included from Hogsback belonged to the clade of mountain-dwelling species, uncorrected sequence divergences between these specimens and other species in that clade ranged from 7.4 to 10.9%. With the exception of the comparison between
Ranges of measurements (mm) for 12 morphometric variables of the
Variable | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|
Holotype | Males ( |
Females ( |
Males | Females | Holotype | Males | Females | Males | Females | |
|
25.3 | 19.5–25.3 | 19.3–25.5 | 15.5–26.9 | 9.1–25.3 | 20 | 20.8–28.7 | 22.7–28.4 | 11.85–24.08 | 9.13–24.71 |
|
37.3 | 27.8–37.5 | 26.8–35.5 | 20.4–38.2 | 11.4–35.1 | 30 | 28.9–42.0 | 31.5–41.3 | 15.9–36.24 | 11.41–34.99 |
|
12.5 | 10.0–14.3 | 10.5–15.0 | 16.8–28.6 | 9.8–27.7 | 10 | 23.3–32.6 | 25.6–32.8 | 12.75–26.38 | 9.84–27.95 |
|
12.8 | 9.0–12.8 | 8.5–12.0 | 4.5–7.7 | 4.5–13.6 | 10 | 10.3–16.4 | 12.4–15.3 | 5.68–13.48 | 4.47–13.12 |
|
3.8 | 3.0–3.8 | 2.5–3.8 | 2.6–3.9 | 1.4–3.6 | 4 | 3.2–4.6 | 3.7–4.5 | 2.06–4.27 | 1.42–3.82 |
|
13.5 | 9.5–13.8 | 9.0–12.5 | 7.7–13.4 | 4.7–12.4 | - | 10.7–15.3 | 11.7–14.5 | 7.03–13.28 | 4.73–14.07 |
|
25 | 18.5–24.5 | 17.8–23.8 | 15.1–26.5 | 9.3–24.6 | 10 | 21.7–29.2 | 22.2–27.6 | 12.57–24.09 | 9.27–23.84 |
|
8 | 6.0–7.8 | 15.0–21.8 | 13.1–42.7 | 6.6–22.7 | - | 5.6–8.1 | 13.5–24.7 | 3.62–7.63 | 3.10–21.57 |
|
39 | 22.0–37.0 | 15.0–21.5 | 5.1–17.7 | 2.4–8.4 | 32 | 19.8–42.1 | 19.2–24.2 | 9.60–25.08 | 6.59–19.15 |
|
16.1 | 9.0–15.3 | 5.0–7.3 | 8.2–17 | 4.5–13.9 | 12 | 8.0–19.4 | 7.3–9.1 | 3.34–12.81 | 2.41–10.84 |
|
15 | 11.0–15.5 | 8.8–12.5 | 7.8–14.9 | 3.1–23.2 | 12 | 11.2–18.5 | 12.7–14.8 | 6.21–14.20 | 1.92–12.62 |
|
4 | 3.0–4.0 | 3.0–4.3 | 3.6–5.9 | 1.9–5.6 | 3 | 4.4–5.5 | 5.2–5.4 | 2.76–4.77 | 1.92–4.44 |
The major cheliped is not always distinctly arched, especially in females and juveniles.
Colouration varies between orange-brown to a darker purple-brown when alive. Tips of the dactyli may be paler in colour, displaying as orange or paler brown/purple.
Currently known only from the Katberg State Forest, the Hogsback State Forest, Madonna and Child Falls and the Hogsback Arboretum, all situated in the Amathole Mountain Range in the Eastern Cape province of South Africa.
The species is named after the Amathole Mountains, part of the Winterberg-Amathole mountain range complex, located on the Great Escarpment in the Eastern Cape. It is currently thought to be endemic to this region. The isiXhosa name ‘Amathole’ translates to ‘calves’ in English and refers to the mountain range, the forest, and the municipal district.
Hogsback and Katberg are both situated in the Keiskamma River catchment. Both sites consist of Southern Mistbelt Forest (FoZ 3), known to be tall, multi-layered, species-rich forests dominated by
The Hogsback (Madonna and Child) Waterfall site is situated inside the Hogsback State Forest. The habitat is represented by a tall, high-flowing stream with different biotopes and pools rich in macro-invertebrate diversity, i.e.,
The second site is situated inside the Hogsback Arboretum Park, downstream from the 39 Steps Waterfall. The habitat is represented by a small stream with pools and the substrate is largely sand with rocks. The edge of the stream is represented by marginal vegetation (i.e.,
The Katberg site is situated in the montane Katberg State Forest. This habitat is comprised of a trickling stream on a very steep slope. The habitat is represented by low and clean water with some other macro-invertebrate diversity, i.e.,
At the Hogsback Arboretum site,
Resolving the distribution of southern African potamonautids is often difficult due to the general cryptic nature of this genus (
16S Sequence divergences among previously known species ranged from 2.1 to 16.9%; the exception being the comparison between
Although South African freshwater crabs have been extensively researched, we continue to find and describe new species (
Dr NAF Miranda is thanked for his invaluable efforts in the field. This work is based on the research supported by the South African Research Chairs Initiative of the Department of Science and Technology (DST) and National Research Foundation (NRF) of South Africa. Any opinion, finding, and conclusion or recommendation expressed in this material is that of the author(s) and the NRF does not accept any liability in this regard. The genetic study presented here was partly supported by a Competitive Programme for Rated Researchers (CPRR13082029507) grant from the National Research Foundation.
Supplementary infromation
phylogenetic