Chaleponcus dabagaensis Kraus 1958
Creators: name: Enghoff, Henrik
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Diplopoda
Spirostreptida
Odontopygidae
Chaleponcus
Chaleponcus dabagaensis

description: Key to species of the Chaleponcus dabagaensis group
The 21 known species of the C. dabagaensis group are almost all quite distinctive in gonopod morphology. A key to the species is given below, but comparison with the gonopod coxa profiles in Fig. 9 will often lead directly to the right species. As new species of the group are likely to be discovered, and as the species in the key may prove to be more variable with regard to number of podous rings and body diameter, any identification should be checked against the detailed gonopod description and illustrations, and the size (no. of podous rings vs. body diameter) should be compared with the diagrams, Figs. 2–3. The limbus (Fig. 4) offers additional diagnostic characters.
The key is based on adult males.
1. Body diameter> 2.5 mm …………………………………………………………………………2
– Body diameter <2.5 mm …………………………………………………………………………5
2. Gonopod coxa with two lateral processes ………………………………………… basiliscus sp. nov.
– Gonopod coxa without lateral processes ……………………………………………………………3
3. Anterior lamella of telomere divided into a horizontal lobe with deeply laciniate edges and a long, straight, distal spine-like part (Fig. 19C). Setation of walking leg tarsi normal (as Fig.5A) … krai sp. nov.
– Anterior lamella of telomere different. Setation of walking legs unusual: claws surrounded by dense ‘palisade’ of setae (Fig. 5 B–C) ………………………………………………………………4
4. Posterior lamella of telomere ending in two long spines. Anterior lamella of telomere with small accessory lamella, otherwise with smooth edges (Fig. 21B) ……… circumvallatus sp. nov.
– Posterior lamella of telomere ending in two short processes. Anterior lamella of telomere with a coarsely dentate basal part (Fig. 22C) …………………………………………………… ibis sp. nov.
5 45–49 podous rings. Body diameter 1.5–1.8 mm (Fig. 2). Cucullus of gonopod coxa subrectangular (Fig. 28). Limbus with spatulate lobes (Fig. 4F) ………………………………… gracilior sp. nov.
– <45 body rings and/or body diameter ≥ 1.9 mm. Cucullus and limbus different …………………6
6 Gonopod coxa with a lateral process ………………………………………………………………7
– Gonopod coxa without a lateral process …………………………………………………………14
7 <40 body rings. Body diameter 1.7–1.8 mm. No dorsal spine on anal valves. Lateral process of gonopod coxa a strongly bent hook (Fig. 14) ……………………………… malleolus sp. nov.
–> 40 body rings. Body diameter ≥ 1.8 mm. Each anal valve with a dorsal spine. Lateral process of gonopod coxa different …………………………………………………………………………8
8 Metaplical shelf of gonopod coxa in two levels between which metaplical shelf-spine fits. Lateral process of gonopod coxa small to inconspicuous (Fig. 24) ……………………… vilici sp. nov.
– Metaplical shelf in one level. Metaplical shelf-spine and lateral process different …………9
9 Lateral margin of gonopod coxa basal to lateral process pronouncedly ‘hunch-backed’ (Figs 12–13) ……………………………………………………………………………………………………10
– Lateral margin of gonopod coxa basal to lateral process not pronouncedly ‘hunch-backed’ ………11
10 Main stem of telomere with thumblike process (Fig. 12D) ………………………… dabagaensis – Main stem of telomere without thumblike process (Fig. 13) …………………… quasimodo sp. nov.
11 Proximal lobe of telomere with long, fluted spine (Figs 10A, 11E) …………………… netus sp. nov. – Proximal lobe of telomere without a spine ………………………………………………………12
12 Lateral process of gonopod coxa small. Cucullus without a large mesal extension (Fig. 17) ……………………………………………………………………………… mwanihanensis sp. nov.
– Lateral process of gonopod coxa larger. Cucullus with a large mesal extension (Figs 15–16) …13
13 Lateral process of gonopod coxa pointed (Figs. 15A) ……………………… scopus sp. nov.
– Lateral process of gonopod coxa broadly rounded, irregularly dentate (Fig. 16B) ……………………………………………………………………………… nikolajscharffi sp. nov.
14 Metaplical shelf-spine of gonopod coxa long, projecting ± mesad (Figs 20 A–B, 23A, D) ………15 – Metaplical shelf-spine not long, projecting ± mesad ……………………………………………16
15 Posterior lamella of telomere divided into a horizontal lobe with spinose edges and a long, straight, distal spine-like part (Fig. 20C, E) …………………………………… nectarinia sp. nov.
– Posterior lamella of telomere with strongly laciniate edges but without a long, straight, spine-like part ………………………………………………………………………… vandenspiegeli sp. nov.
16 Metaplical shelf of gonopod coxa in two levels between which metaplical shelf-spine fits. Gonopod coxa with a small to inconspicuous lateral process (Fig. 24) ………… vilici sp. nov.
– Metaplical shelf in one level. Metaplical shelf-spine different …………………………………17
17 Gonopod coxa with distal hook-like extension (Fig. 31A). 41 podous rings, body diameter 1.6 mm ………………………………………………………………………………………… tintin sp. nov.
– Gonopod coxa without distal hook-like extension. Mostly>41 podous rings and/or body diameter> 1.6 mm ………………………………………………………………………………18
18 Anal valves without dorsal spines (Fig. 6D) ……………………………………… teres sp. nov.
– Each anal valve with a dorsal spine ……………………………………………………………19
19 Cucullus of gonopod coxa subrectangular in outline (Fig. 26 B–C) ………… hamerae sp. nov.
– Outline of cucullus more rounded ……………………………………………………………20
20 Anterior lamella of gonopod telomere with long, smooth spine (Fig. 30 C–D) …… howelli sp. nov.
– No such spine ……………………………………………………………………………………21
21 Anterior lamella of gonopod telomere divided into two triangular lobes with serrate margins (Fig. 27B, E). Posterior lamella simple …………………………………………… termini sp. nov.
– Anterior lamella of gonopod telomere simple. Posterior lamella with a slender, spinose branch with a long, thin, bifurcate side branch (Fig. 29E) ………………………………… mwabvui sp. nov.
Distribution and habitat
Fig. 32 shows the distribution of the 21 species of the Chaleponcus dabagaensis group plotted on a semi-diagrammatic map of the Forest Reserves (FR) from which species of the group have been collected. Fifteen of the species have been collected in only one FR, with New Dabaga/Ulangambi FR being the richest (6 exclusive species, 11 species in all).
Five species are shared between two FR, and C. gracilior sp. nov. even occurs in four FR, being clearly the most widespread of the species. The easternmost FR, Mwanihana, does not share any species with any other FR.
As Fig. 1 clearly shows, there are several forested areas in the Udzungwa Mts where the C. dabagaensis group has not been collected. This is probably due to a collecting bias, since the very comprehensive millipede material from the Udzungwa Mts kept in ZMUC largely derives from the FRs where the C. dabagaensis group is now known to occur. Additional collection effort, especially in the large southerncentral Matundu forest, is likely to reveal several additional species of the group. Even renewed collecting in the forest reserves already sampled is likely to reveal new species, since three (ibis sp. nov., vandenspiegeli sp. nov., tintin sp. nov.) out of the 21 species are singletons and one (circumvallatus sp. nov.) is a doubleton (Fig. 33).
The Chaleponcus dabagaensis group consists of high-altitude species, all material having been collected at 1390–2100 m asl, and with the highest species diversity above 1700 m (Table 2). The vast majority of specimens was collected in montane forest, but some species were found in disturbed habitats as well, e.g., the relatively widespread C. gracilior sp. nov. Very often several (up to 5) species were represented in a sample, but whether such coexisting species occupy different microhabitats is not known.
Two notes on general morphology
Torsion of the gonopod telopodite
Torsion of the gonopod telopodite is characteristic of the majority of species of Odontopygidae and the related family Spirostreptidae (Kraus 1966, Hoffman 2008) and is important for the function of the gonopod (Barnett & Telford 1996). In all odontopygids examined by me the torsion always begins with an anteriad bend, i.e., the torsion is clockwise when followed from coxa towards the gonopod tip and viewed from a mesal point of view on the RIGHT gonopod. Published drawings by, e.g., Kraus (1966) and Frederiksen (2013a,b) confirm the generality of this pattern.
Intercalary cuticular microscutes
Very small (ca. 1 µm) circular microstructures were frequently observed between cuticular microscutes on body rings (Fig. 34). Similar structures were reported by Akkari & Enghoff (2011) from several families of the order Polydesmida and have also been observed on Lusitanipus alternans (Verhoeff, 1893) (Callipodida: Dorypetalidae) (HE and S. Reboleira unpublished), but have not been recorded from other millipede orders. Such intercalary cuticular microscutes are, however, discernible on fig. 8 of Frederiksen (2013a) (Chaleponcus parensis Frederiksen, 2013), as well as on fig. 1 of Frederiksen (2013b) (Lamelloramus rhombiformis Frederiksen, 2013b). They have also been observed on a species of the genus Aquattuor Frederiksen, 2013, and may be widespread in Odontopygidae. The nature of the microscutes is unknown. In a preparation of C. nikolajscharffi sp. nov. some of the microscutes give rise to projecting, club-shaped outgrowths of a few µm length (Fig. 34D) which may represent parasitic fungi of a kind?
description: Published as part of Enghoff, Henrik, 2014, A mountain of millipedes I: An endemic species-group of the genus Chaleponcus Attems, 1914, from the Udzungwa Mountains, Tanzania (Diplopoda, Spirostreptida, Odontopygidae), pp. 1-75 in European Journal of Taxonomy 100 (100) on pages 67-70, DOI: 10.5852/ejt.2014.100, http://zenodo.org/record/3860450