Chaleponcus dabagaensis, Kraus, 1958

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), European Journal of Taxonomy 100, pp. 1-75 : 67-70

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?

Figures

Fig. 9. Chaleponcus spp., outline of coxite of left gonopod, posterior view. (The ’transverse’ plane of the gonopod is usually slightly at angles with the exact transverse plane of the millipede, so it may be necessary to tilt the gonopod slightly in order to obtain the view shown on the drawings.) The stippled lines indicate the place where the telopodital basomere emerges from the coxal cavity. Not to scale.

Fig. 2. Body size of males of 13 species of the Chaleponcus dabagaensis group: Number of podous rings and vertical midbody diameter in large, small and ‘long, thin’ species (cf. text), as well as medium sized species in which the gonopod coxa has an obvious lateral process.

Fig. 3. Body size of males of 8 species of the Chaleponcus dabagaensis group: Number of podous rings and vertical midbody diameter in medium-sized species in which the gonopod coxa has no obvious lateral process.

Fig. 4. Limbus types in Chaleponcus species, SEM micrographs, external view, except I: internal view. — A. Lobes pointed, more than twice as long as broad (C. scopus sp. nov.). B. Lobes pointed, slightly less than twice as long as broad (C. howelli sp. nov.). C. Lobes pointed, almost equilateral triangles (C. netus sp. nov.), D. Lobes rounded, slightly longer than broad (C. dabagaensis Kraus, 1958). E. Lobes broadly rounded, slightly shorter than broad (C. hamerae sp. nov.). F. Lobes spatulate (C. gracilior sp. nov.). G. Lobes rounded, broader than long, spinose, ridged (C. krai sp. nov.). H. Lobes ca. 3 times as broad as high, rounded, spinose (C. teres sp. nov.). I. Lobes rounded, much broader than high, smooth (C. malleolus sp. nov.). J. No lobes (C. circumvallatus sp. nov.). Scales: 0.01 mm (A– F, J), 0.001 mm (G–I).

Fig. 19. Chaleponcus krai sp. nov., gonopods. Specimens from New Dabaga-Ulangambi (A) and Kalimbazi Mtn (B-D). A. Left gonopod, anterior view. B–D. Right gonopod. B. Mesal-dorsal view. C. Telopodite, mesal view. D. Posterior view. al = anterior lobe of telomere, cu = cucullus, il = intermediate lobe of telomere, mfp = metaplical flange process, mss = metaplical shelf-spine, pl = posterior lobe of telomere, ps = proximal spine of solenomere. Scales 0.1 mm.

Fig. 5. Chaleponcus spp., tip of tarsus and claw of walking legs. — A. C. mwanihanensis sp. nov. as an example of normal setation. B–C. C. circumvallatus sp. nov. with the claw surrounded by a ’palisade’ of setae. Scales 0.1 mm.

Fig. 21. Chaleponcus circumvallatus sp. nov., left gonopod. A. Anterior view. B. Mesal-anterior view. C. Posterior view. D. Mesal-posterior view. al = anterior lobe of telomere, al’ = accessory lamella, cu = cucullus, mfp = metaplical flange process, mp = mesal metaplical process, ms = metaplical shelf, mss = metaplical shelf-spine, pl = posterior lobe of telomere, ps = proximal spine of solenomere. Scales 0.1 mm.

Fig. 22. Chaleponcus ibis sp. nov., left gonopod. A. Posterior view. B. Anterior view. C. Telopodite, mesal-anterior view. al = anterior lobe of telomere, al’ = accessory lamella?, cu = cucullus, mp = mesal metaplical process, ms = metaplical shelf, mss = metaplical shelf-spine, pl = posterior lobe of telomere, ps = proximal spine of solenomere. Scales 0.1 mm.

Fig. 28. Chaleponcus gracilior sp. nov., gonopods. A. Gonopods in situ in body ring 7, anterior view. B. Right gonopod, detail of base of solenomere, showing basal side branch consisting of a tiny, spinelike part and a larger, irregularly lamellate one. C. Right gonopod, anterior-mesal view. D. Left gonopod, posterior view. E. Left telopodite, posterior-lateral view. F. Right telopodite, anterior view. al = anterior telomeral lamella, cu = cucullus, dp = distal telomeral process, mf = metaplical flange, ms = metaplical shelf, mss = metaplical shelf-spine, pb = proximal side branch of solenomere, pl = posterior telomeral lamella, prl = proplical lobe. Scales: 0.1 mm (A, C–F), 0.05 mm (B).

Fig. 14. Chaleponcus malleolus sp. nov., right gonopod. A. Anterior view. B. Mesal view, focus on coxa. C. Posterior view. D. Anterior-mesal view. E. Mesal view, focus on telopodite. F. Telopodite, ventral-posterior view. al = anterior lamella of telomere, cu = cucullus, mfp = metaplical flange process, mp = mesal metaplical process, mss; metaplical shelf-spine, pl1, pl2, pl3 = lobes of posterior lamella of telomere, st = main stem of telomere. Scales 0.1 mm.

Fig. 24. Chaleponcus vilici sp. nov., left gonopod. A. Posterior view. B. Mesal view. C. Mesal-anterior view. D. Close-up of metaplical shelf-spine, mesal view. E. Anterior (and slightly apical/ventral) view. F. Telopodite, distal view, showing solenomere and the two distal telomere branches. al = anterior lamella of telomere, cu = cucullus, la = lateral angle of coxa, mf = metaplical flange, mp = mesal metaplical process, ms = metaplical shelf, mss = metaplical shelf-spine, pl = posterior lamella of telomere, slm = solenomere. Scales: 0.1 mm (A–D), 0.01 mm (E–F).

Fig. 12. Chaleponcus dabagaensis Kraus, 1958, left gonopod. — A. Anterior view. B. Posterior view. C. Mesal-ventral view. D. Mesal-dorsal view. al = anterior lamella of telomere, mf = metaplical flange, mp = mesal metaplical process, ms = metaplical shelf, mss = metaplical shelf-spine, pl = posterior lamella of telomere, ps = proximal spine of solenomere, st = main telomeral stem, th = thumblike process of telomere main stem. Scales 0.1 mm.

Fig. 13. Chaleponcus quasimodo sp. nov., left gonopod. A. Anterior view. B. Anterior-mesal view. C. Ventral view. D. Posterior view. al = anterior lamella of telomere, mf = metaplical flange, mp = mesal metaplical process, ms = metaplical shelf, mss = metaplical shelf-spine, pl = posterior lamella of telomere, ps = proximal spine of solenomere. Scales 0.1 mm.

Fig. 10. Chaleponcus netus sp. nov., left gonopod, coloured. — A. Posterior view. B. Ventral view. Orange = coxite, blue = torsotope, yellow = solenomere (slm), green = proximal spine of solenomere (ps), pink = telomere. pxs = spine on proximal telomeral lobe, st = main stem of telomere. Scales 0.1 mm.

Fig. 11. Chaleponcus netus sp. nov., gonopods. — A. Gonopods, anterior view. B. Left coxite, mesal view. C. Base of proximal solenomere spine (ps) with spinose socket. D. Right gonopod, anterior (and slightly mesal) view. E. Left gonopod telopodite, posterior view. F. Base of proximal solenomere spine (ps) in a different individual, with denticle (ps2). al = anterior lamella of telomere, il = intermediate lamella of telomere, mfp = metaplical flange process, ms = metaplical shelf, mss = metaplical shelfspine, pl = posterior lamella of telomere, ps = proximal spine of solenomere, ps2 = additional proximal spine of solenomere, pxl = proximal lobe of telomere, pxs = spine on proximal lobe of telomere. Scales: 0.1 mm (A–B, D–E), 0.05 mm (C, F).

Fig. 17. Chaleponcus mwanihanensis sp. nov., gonopods. A. Left gonopods, mesal-ventral view. B. Left gonopod, posterior view. C. Right gonopod, ventral view. D. Right gonopod, anterior view. al = anterior lamella of telomere, cu = cucullus, lp = lateral coxal process, mf = metaplical flange, ms = metaplical shelf, mss = metaplical shelf-spine, pl = posterior lamella of telomere. Scales 0.1 mm.

Fig. 15. Chaleponcus scopus sp. nov., right gonopod. A. Posterior view. B. Ventral-posterior view. C. Mesal-posterior view. D. Anterior view. al = anterior lamella of telomere, al’ = thumblike process of al, cu = cucullus, lp = lateral coxal process, mf = metaplical flange, mp = mesal metaplical process, msl = metaplical shelf-forming lobe, mss = metaplical shelf-spine, pl = posterior lamella of telomere, ps = proximal solenomeral spine, slm = solenomere. Scales 0.1 mm.

Fig. 16. Chaleponcus nikolajscharffi sp. nov., right gonopod. A. Mesal view. B. Anterior view. C. Ventral view. D. Posterior view. al = anterior lamella of telomere, cu = cucullus, lp = lateral coxal process, mf = metaplical flange, mp = mesal metaplical process, msl = metaplical shelf-forming lobe, mss = metaplical shelf-spine, pl = posterior lamella of telomere, ps = proximal spine of solenomere. Scales 0.1 mm.

Fig. 20. Chaleponcus nectarinia sp. nov., gonopods. A. Right gonopod, posterior (-lateral) view. B. Right gonopod, anterior view. C. Tip of posterior lamella of telomere. D. Left gonopod, mesal (-posterior) view. E. Right gonopod, mesal view. al = anterior lobe of telomere, cu = cucullus, mfp = metaplical flange process, ms = metaplical shelf, mss = metaplical shelf-spine, pl = posterior lobe of telomere, ps = proximal spine of solenomere. Scales 0.1 mm.

Fig. 31. Chaleponcus tintin sp. nov., left gonopod. A. Anterior view. B. Mesal-anterior view. C. Ventral (-anterior) view. D. Posterior (-mesal) view. al = anterior telomeral lamella, cu = cucullus, mfp = metaplical flange process, ms = metaplical shelf, mss = metaplical shelf-spine, pl = posterior telomeral lamella, plb = basal branch of pl, ps = proximal spine on solenomere. Scales 0.1 mm.

Fig. 6. Telson types in Chaleponcus species. — A. Dorsal and ventral anal valve spines well developed (C. nectarinia sp.nov.).B.Spinesverylong(C.circumvallatussp.nov.).C.Dorsal spinewell developed, ventral spinebarelyindicated(C.mwabvuisp.nov.).D.Nospines(C.teressp.nov.).E.Setiferoustuberclesonravelins (C. nectarinia sp. nov.). F. With setiferous tubercles, not on ravelins (C. mwabvui sp. nov.). Scales 0.1 mm.

Fig. 26. Chaleponcus hamerae sp. nov., left gonopod. A. Mesal-anterior view. B. Posterior view. C.Anterior view. D. Ventral view. al, al’ = anterior telomeral lamella, cu = cucullus, mf = metaplical flange, ms = metaplical shelf, mss = metaplical shelf-spine, pl = posterior telomeral lamella, prl = proplical lobe, pls = spine on pl. Scales 0.1 mm.

Fig. 30. Chaleponcus howelli sp. nov., left gonopod. A. Mesal-ventral (-anterior) view. B. Posterior view. C. Anterior view. D. Ventral (-anterior) view. al = anterior telomeral lamella, als = spine on al, cu = cucullus, mf = metaplical flange, mp = mesal metaplical process, ms = metaplical shelf, mss = metaplical shelf-spine, pl = posterior telomeral lamella, ps = proximal spine on solenomere, sts = spine on telomeral main stem. Scales 0.1 mm.

Fig. 27. Chaleponcus termini sp. nov., gonopods. A. Right gonopod, posterior view. B. Right gonopod, anterior view. C. Left telopodite, mesal-ventral view. D. Left coxite, mesal view. E. Right telopodite, anterior-ventral view. al1, al2 = anterior telomeral lobe, cu = cucullus, mf = metaplical flange, ms = metaplical shelf, mss = metaplical shelf-spine, pl = posterior telomeral lamella, ps = proximal spine on solenomere. Scales 0.1 mm.

Fig. 29. Chaleponcus mwabvui sp. nov., right gonopod. A. Posterior view. B. Anterior-mesal view. C. Coxa, tip, anterior view. D. Telopodite, apical-dorsal view. E. Process plp of telomere. al = anterior telomeral lamella, cu = cucullus, mf = metaplical flange, mp = mesal metaplical process, ms = metaplical shelf, mss = metaplical shelf-spine, pl = posterior telomeral lamella, plp1, plp2, posterior telomeral lamella processes, ps = proximal spine on solenomere, slm = solenomere. Scales: 0.1 mm (A–D), 0.05 mm (E).

Fig. 32. Distribution of species of the Chaleponcus dabagaensis group in Forest Reserves of the Udzungwa Mts. The position of the Forest Reserves in relation to each other approximately corresponds to their true relative positions, cf. Fig. 1. Underlined species acronyms denote species known only from one Forest Reserve. Shared species are shown on lines connecting the circles. – Forest Reserve acronyms: KIG = Kigogo, KK = Kiranzi/Kitunguli, KR = Kisinga/Rugaro, MWA = Mwanihana, NDU = New Dabaga/Ulangambi, US = Udzungwa Scarp, WKS = West Kilombero Scarp. – Species acronyms: BAS = basiliscus, CIR = circumvallatus, DAB = dabagaensis, GRA = gracilior, HAM = hamerae, HOW = howelli, IBI = ibis, KRA = krai, MAL = malleolus, MWB = mwabvui, MWN = mwanihanensis, NEC = nectarinia, NET = netus, NIK = nikolajscharffi, QUA = quasimodo, SCO = scopus, TES = teres, TEM = termini, TIN = tintin, VAN = vandenspiegeli, VIL = vilici.

Fig. 1. Map of the Udzungwa Mountains, showing the location of the forest reserves (green rings) where the material studied here was collected, as well as names of individual mountains in West Kilombero FR. Based on fig. 1 in Marshall et al. (2010).

Fig. 33. The number of studied specimens (males) per species.

Fig. 34. Intercalary cuticular microscutes in Chaleponcus spp. A. C. netus sp. nov. B. C. tintin sp. nov. C–D. C. nikolajscharffi sp. nov. Fig. D shows fungus-like outgrowths from scutes. Scales 0.001 mm.