Genus Morogorius Verhoeff, 1941

Morogorius Verhoeff, 1941: 249.

Type species

Morogorius pallidus Verhoeff, 1941 (Tanzania) by monotypy.

Other included species

Morogorius divisus Enghoff sp. nov.

Morogorius louishanseni Enghoff sp. nov.

Morogorius pugio Enghoff sp. nov.

Morogorius kitungulu Enghoff sp. nov.

Morogorius cochlear Enghoff sp. nov.

1 fide Carl (1909), Chamberlin (1952)

2 fide Carl (1909), Silvestri (1909)

History and diagnosis

The history of Morogorius is brief. In the original description, it was placed in subfamily Cordyloporinae Brölemann, 1916 (now: Prepodesminae) and was diagnosed as follows (translated from Verhoeff 1941: 249): “This genus is based on the absence of dorsal processes, on lack of denticulation on the paranota as well as on the hind margin of the diplosomites between paranota and sterna, and on characters of the gonopods” and “Different from the related genera Cordyloporus, Paracordyloporus, Scolopopleura and Graphidochirus in the gonopods, in part also in body characters” (Verhoeff 1941: 249–250). Chamberlin (1952) didn’t mention Morogorius, nor did Demange & Mauriès (1975). Hoffman (1977) restudied and re-drew the gonopods of the type species and compared it to his Tanzaniella howelli Hoffman, 1977. That’s all.

A useful differential diagnosis of Morogorius is thus not available, as is the case for very many millipede genera. Considering the very large number of genera in Chelodesmidae, in combination with the lack of useful diagnoses of the family Chelodesmidae and the subfamily Prepodesminae, such a diagnosis cannot be presented here. However, Morogorius differs from other Tanzanian genera of Chelodesmidae in the characters presented in Table 2. The homology of the largest gonopodal process in Morphotelus and Mesodesmus is uncertain, therefore the process may preliminary be termed “solenophore”.

General description of Morogorius (males)

SIZE. Length 21–31 mm, max. width 3.6–5.7 mm. Collum wider than head but narrower than ring 2, roughly parallel-sided from ring 3 to midbody, thereafter moderately tapering.

COLOUR. Overall colour (reddish) brown, in part (species-specific) with some or all paranota contrastingly pale (Fig. 2A–B).

HEAD (Fig. 3A–B). Densely setose below and between antennal sockets, labrogenal offset not very pronounced, epicranial groove distinct, interantennal space narrow, 0.5–0.6 × length of antennomere 2. Antennae reaching back to ring 6 when stretched.

COLLUM (Fig. 3A, C). In the shape of an isosceles curved trapezoid with the longer margin anteriorly, lateral corners smoothly rounded, surface granular, especially laterally. A row of 2–4 setae close to anterior margin.

BODY RINGS (Figs 3C–H, 7, 10B–F). Prozonites smooth, with simple, cellular microsculpture (Fig. 3D). Metazonites flat, granular dorsally and laterally, 1.4–1.8 × as broad as prozonites, with 1+1 small, thin setae anteriorly (setae apparently absent in M. pugio Enghoff sp. nov.) and a prominent transverse sulcus on rings 5–18. Paranota horizontal, those of rings 2–3 very slightly projecting forwards, following paranota rectangular but from some point (ring 5–15 according to species) with posterior corners increasingly projecting backward. Paranotal microsculpture (Fig. 10D) formed by longitudinally stretched, narrow cytoscutes of more or less irregular shape. Ozopore formula normal (5, 7, 9–10, 12– 13, 15–19), ozopores circular, delimited by smooth ring in peritremata on edge of paranota, ca midway between anterior and posterior margin. Sterna (Fig. 4E) broad, with a transverse impression and a row of fine setae near anterior margin. Spiracles (only studied in M. divisus Enghoff sp. nov.): anterior spiracle on each diploring pear-shaped, posterior spiracle subcircular, both with plugs showing a very pronounced cellular pattern (Fig. 3G). Limbus (Fig. 4F) with straight margin, consisting of a densely, finely striate marginal zone preceded by a row of rectangular cells.

LEGS (Figs 4C–D, 10F). Slender, without modifications, length 1.2–1.6 × maximum body width, length not increasing towards hind end,

TELSON (Fig. 4A–B). Preanal ring with several setae along dorsal part of posterior margin; epiproct large, with prominent lateral setiferous tubercles; spinnerets arranged in an almost quadratic trapezoid on a smooth terminal swelling, simple, flanked by 1+1 globular, sometimes partly collapsed structures. Anal valves (paraprocts, pp) unmodified, each with 2 setae, dorsal seta (ds) on marginal rim, ventral seta (vs) more lateral, Subanal scale (hypoproct, hp) semicircular, unmodified, with 1+1 marginal setae.

GONAPOPHYSES. Short, triangular.

GONOPOD APERTURE. Transversely oval, more than twice as broad as long, rim simple.

GONOPODS (Figs 5–6, 8–9, 11–12). No sternal remnant. Coxa (cx) cylindrical, short, length ≈ diameter (perhaps slightly longer in M. pallidus), with a conical process (cxp) distally on the anterior side (absent to barely discernible in M. divisus sp. nov.); two long setae on anterior surface basal to process, a field of up to ca a dozen setae (ls) on lateral surface (except in M. louishanseni sp. nov. and perhaps M. pallidus) and numerous setae on meso-posterior surface. Cannula (ca) stout. Prefemoral part (prf) bent at right angles relative to cx, cylindrical: length 2–2½ × diameter (maybe slightly less in M. pallidus), numerous long setae on ventral surface. Efferent canal running straight on meso-dorsal side of prf, at level of base of parasolenomere bending laterad into solenomere; prefemoral process (prp) originating dorso-laterally from main body of prf, at least as long as solenomere and parasolenomere, basally slender, apically more or less expanded, of species-specific shape and curving over solenomere and parasolenomere; prf distally delimited by cingulum (ci), cingulum very distinct on ventral side of gonopod (except in M. kitungulu Enghoff sp. nov. where it is less distinct). Acropodite: main body strongly reduced, indiscernible, giving rise to solenomere and parasolenomere. Solenomere (slm) slightly shorter than prp (apparently same length in M. pallidus according to the original decription of that species), several times as long as broad, of species-specific shape, either regularly tapering or abruptly narrowing at ⅔ of its length. Parasolenomere (ps) originating mesal to slm, of species-specific shape, more or less shorter than slm, sometimes simple, sometimes deeply divided into two branches.

The following descriptions of individual species of Morogorius focus on species-specific characteristics. For body parts which are not mentioned, the general description of genus Morogorius applies.