Aquattuor Frederiksen, 2013

Enghoff, Henrik, 2020, A mountain of millipedes VIII. The genus Aquattuor Frederiksen, 2013 revisited - a new species from the Udzungwa Mts, Tanzania, another from the Nguru Mts, and introduction of the first pair of male legs as a source of taxonomic characters (Diplopoda, Spirostreptida, Odontopygidae), European Journal of Taxonomy 626, pp. 1-32 : 4-5

Genus Aquattuor Frederiksen, 2013

Diagnosis (modified after Enghoff & Frederiksen 2015)

Differs from all other Odontopygidae by the structure of the limbus, which consists of large, rectangular, easily detachable flaps. Gonopods of the Prionopetalini type, i.e., basomere of telopodite with a torsate flexible zone followed by a posttorsal narrowing; solenomere elongated. Gonopodal proplica apically expanded into a distal palette; metaplica with an oblique flange; solenomere simple, thin and whip-like; telomere terminating in a long, curved, gutter-like to tubular part.

Descriptive notes

For characters not mentioned here, see Enghoff & Frederiksen (2015).

Mandibular stipes ( Fig. 2 ): in males, but not in females with a disto-ventral expansion.

First pair of male legs: in the genus Aquattuor the first pair of legs is remarkably diverse. Figs 3–7 illustrate the first pair of legs in all known species of the genus, with a focus on the prefemur. In all of them, the prefemur carries a more or less finger-shaped process (pfp) which projects orad from the anterior surface of the prefemur ( Figs 3–7 ). The distal (ventral) surface of the process is smooth, the basal (dorsal) surface is more or less scaly-rugose. The shape of the process varies from slender fingershaped to relatively broad/triangular, and in one species ( A. nguruensis sp. nov.) there is a clearly delimited depression (pfd) on the distal surface of the process ( Fig. 4 A–C). In A. major Enghoff, 2015 , A. longipala Enghoff, 2015 and A. mollilobus sp. nov. there is in addition a second, more distal, more irregularly shaped prefemoral lobe (dpl, Figs 5–6 ).

Another type of variation is seen in the setation of the telopodites of the first pair of legs ( Fig. 8 ). Here, A. mollilobus sp. nov. ( Fig. 8C ) stands out by having very short setae on all podomeres. Aquattuor major and A. longipala have long setae on the tarsus, but very short ones on the femur ( Fig. 8B ). The remaining species have long setae (same length as on the following leg-pairs) on all podomeres ( Fig. 8A ). These differences in setation do not seem to reflect the setation of normal walking legs.

In one species ( A. udzungwensis ), the podomeres distal to the prefemur of the first leg pair seem to be invariably missing (several specimens examined) ( Fig. 7 D–E).

Adhesive pads on walking legs are absent.

Included species (alphabetically)

Aquattuor claudiahempae Enghoff & Frederiksen, 2015

A. denticulatus Frederiksen, 2013 (type species)

A. fasciatus ( Attems, 1896)

A. longipala Enghoff, 2015

A. major Enghoff, 2015

A. mollilobus sp. nov.

A. nguruensis sp. nov.

A. stereosathe Enghoff, 2015

A. submajor Enghoff, 2015

A. udzungwensis Enghoff, 2015

Figures

Fig. 2. Aquattuor udzungwensis Enghoff, 2015, specimens from Chita, heads, lateral view. A. Male (NHMD 621667). B. Female (NHMD 621667). Scale bars = 0.1 mm. The arrow points at the distoventral stipital expansion lobe in the male.

Fig. 3. Aquattuor spp., first pair of male legs. A–C. A. fasciatus (Attems, 1896), non-type male from Zanzibar (NHMD 621641). D–F. A. claudiahempae Enghoff & Frederiksen, 2015, paratype from Kilimanjaro (NHMD 621638). G–I. A. claudiahempae, specimen from Udzungwa Mts (NHMD 621639). A, D, G. Anterior view. B, E, H. Sublateral view. C, F, I. Ventral view. Abbreviation: pfp = prefemoral process. Scale bars = 0.1 mm.

Fig. 4. A–C. Aquattuor nguruensis sp. nov., holotype, ♂ (VMNH110617), first pair of legs. Notice mite larva (”hypopus”) on left femur. D–F. A. denticulatus Frederiksen, 2013, paratype, ♂ (NHMD 621640), left leg of first pair. A, D. Anterior view. B, E. Sublateral view. C, F. Sub-ventral view. Abbreviation: pfd = prefemoral depression. Scale bars = 0.1 mm.

Fig. 5. Aquattuor spp., first pair of male legs. A–C. A. major Enghoff, 2015, paratype, ♂ (NHMD 621644), first pair of legs in situ. D–F. A. longipala Enghoff, 2015, male from Udzungwa Mts National Park, Mito Mitatu (NHMD 621642). A, D. Anterior view. B, E. Sublateral view. C, F. Sub-ventral view. Abbreviations: dpl = distal prefemoral lobe; pfp = prefemoral process. Scale bars = 0.1 mm.

Fig. 6. Aquattuor spp., first pair of male legs. A–C. A. mollilobus sp. nov., paratype, ♂ (NHMD 621647). D–F. A. stereosathe Enghoff, 2015, paratype, ♂ (NHMD 621650). A, D. Anterior view. B, E. (Sub)- lateral view. C, F. (Sub)-ventral view. Abbreviations: dpl = distal prefemoral lobe; pfp = prefemoral process. Scale bars = 0.1 mm.

Fig. 7. Aquattuor spp., first pair of male legs. A–C. A. submajor Enghoff, 2015, paratype, ♂ (NHMD 621651). A. Anterior view. B. Sublateral view. C. Ventral view. D–E. A. udzungwensis Enghoff, 2015, male from Udzungwa Mts National Park, Kidatu (NHMD 621662). D. Anterior view. E. Ventral view. Scale bars = 0.1 mm.

Fig. 8. Aquattuor spp., males, left leg of first pair. A. A. stereosathe Enghoff, 2015, paratype, ♂ (NHMD 621650): setae same length as in normal walking legs. B. A. longipala Enghoff, 2015, specimen from Udzungwa Mts National Park, Mito Mitatu (NHMD 621642): setae of femur shortened. C. A. mollilobus sp. nov., paratype, ♂ (NHMD 621646): all setae shortened. Scale bars = 0.1 mm.