Pseudotropheina Oliver 2024, new subtribe
Creators: name: Oliver, Michael K.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Perciformes
Cichlidae

description: Pseudotropheina Oliver, 2024 new subtribe
Diagnosis
A distinct clade, the " mbuna, " within the Pseudocrenilabrini. This subtribe is characterised in part by a single-nucleotide polymorphism (SNP) in a transcription factor, irx 1 b, of the WNT signalling pathway in the forebrain. In the Pseudotropheina (25 species screened in 11 genera), this nucleotide is fixed as T, versus C in both the Cyrtocarina (47 species in 25 genera) and Rhamphochromina (5 species representing all three genera) (details in Sylvester et al. (2010)). Despite repeated assertions, no definite morphological synapomorphies diagnosing the mbuna clade have been identified (see discussion in Oliver and Arnegard (2010)). However, several morphological characteristics can discriminate the members of this clade from those of the other two Lake Malawi subtribes, although not from certain riverine and Lake Victoria Pseudocrenilabrini. These attributes include: scales on the chest that are abruptly smaller than those of adjacent body regions (versus with gradual change in chest scale size); anal fin of males bearing true ocelli (prominent rounded yellow to orange spots bordered with a narrow transparent ring) in the posterior half of the fin (versus with variously-shaped coloured areas in anal fin that are never surrounded with a transparent ring); and left ovary atrophied (versus both ovaries of similar size; however, an atrophied left ovary is found also in some Rhamphochromina). The number of vertebrae posterior to those bracketing the last occupied dorsal insertion space completely separates the Pseudotropheina (with 6–9) from the Rhamphochromina (with 10–13), although members of these two subtribes are unlikely to be mistaken for each other.
Type genus: Pseudotropheus Regan, 1922
Included genera: Abactochromis Oliver & Arnegard, 2010; Chindongo Li, Konings, & Stauffer, 2016; Cyathochromis Trewavas, 1935; Cynotilapia Regan, 1922; Genyochromis Trewavas, 1935; Gephyrochromis Boulenger, 1901; Iodotropheus Oliver & Loiselle, 1972; Labeotropheus Ahl, 1926; Labidochromis Trewavas, 1935; Maylandia Meyer & Foerster, 1984; Melanochromis Trewavas, 1935; Petrotilapia Trewavas, 1935; Pseudotropheus Regan, 1922; Tropheops Trewavas, 1984.
Distribution
Lake Malawi and the upper Shire River (Ribbink et al. 1983).
Notes
Phylogenomic analysis, based on ultraconserved element (UCE) markers, also consistently resolves the mbuna as a highly-supported clade (McGee et al. 2016, Hulsey et al. 2017; D. Hulsey in litt. 2 - Oct- 2022), but the specific SNPs have evidently not been reported.
Hoedeman (in Hoedeman and de Jong (1947)) previously proposed a tribe Pseudotropheini, but this was published as a name only and, thus, under Article 13 of the Code is not available (Van der Laan et al. 2014: 109). Subsequently, Tawil (2001): 78, 81 mentioned a " sous-tribu des Pseudotropheina ", but this too fails to satisfy certain requirements for availability: for all new names published after 1999, Article 16.1 requires that they be indicated explicitly as intentionally new; Article 16.2 requires citation of the name of the type genus. Tawil's uses of " Pseudotropheina " do not satisfy these requirements. I had independently selected Pseudotropheina as the most logical and recognisable name for Lake Malawi’s mbuna clade months before becoming aware of these invalid prior mentions of this name.
Vertebral and pterygiophore counts and most-frequent insertion patterns of the latter, are summarised in Tables 1, 2. Notably, the minimum number of anal pterygiophores (8) in the Pseudotropheina is lower than that of its larger sister clade Cyrtocarina in which the minimum is nine.
Other Pseudocrenilabrini
In addition to the above five subtribes, the Pseudocrenilabrini contains further genera whose phylogenetic positions within the tribe have not yet been resolved. These are:
The Serranochromis informal group (Eccles and Trewavas 1989, Greenwood 1993) with Chetia Trewavas, 1961; Sargochromis Regan, 1920; Serranochromis Regan, 1920; and Pharyngochromis Greenwood, 1979, all of which I consider to be genera incertae sedis in Pseudocrenilabrini, as no synapomorphy, whether morphological or molecular, has been identified;
Other nominal genera incertae sedis in Pseudocrenilabrini: Allochromis Greenwood, 1980; Astatotilapia Pellegrin, 1904; Astatoreochromis Pellegrin, 1904; Ctenochromis Pfeffer, 1893; Cyclopharynx Poll, 1948; most Haplochromis Hilgendorf, 1888 spp.; Lithochromis Lippitsch & Seehausen, 1998; Mbipia Lippitsch & Seehausen, 1998; Neochromis Regan, 1920; most Orthochromis Greenwood, 1954 spp.; Paralabidochromis Greenwood, 1956; Pundamilia Seehausen & Lippitsch, 1998; Pyxichromis Greenwood, 1980; Schubotzia Boulenger, 1914; Schwetzochromis Poll, 1948; and Thoracochromis Greenwood, 1979.
One hopes that further molecular phylogenetic studies will be able to elucidate the relationships of these genera, many of which may not be monophyletic. Eventually, if found to constitute a monophyletic group, many species in the incertae sedis genera could be placed in a pseudocrenilabrine subtribe Haplochromina Hoedeman 1947, which would be possible because Haplochromis and Pseudocrenilabrus would then be in different subtribes.
description: Published as part of Oliver, Michael K., 2024, African cichlid fishes: morphological data and taxonomic insights from a genus-level survey of supraneurals, pterygiophores, and vertebral counts (Ovalentaria, Blenniiformes, Cichlidae, Pseudocrenilabrinae), pp. e 130707 in Biodiversity Data Journal 12 on page e130707, DOI: 10.3897/BDJ.12.e130707