Agabus ruwenzoricus Guignot, 1936 Figures 1, 4B, 8C, 11C, 11H, 12, 13, 14, 15

Agabus (Agabinectes) pallidus var. ruwenzoricus Guignot, 1936: 49

Type locality.

"Uganda. Mons Ruwenzori, versant est, 3.000 à 4.000 m." [Uganda, Mount Ruwenzori, eastern slope, 3000 to 4000 m].

Type material.

[Not examined]: Information about type specimens from Nilsson (1992a): "Lectotype here designated in NMNH (coll. Guignot) labelled: 'Monts Ruwenzori versant est zone alpine 3000 4000 m Ch. Alluaud I 1909', '3000 m’, ‘♂’, and my lectotype label; paralectotype ♂ with same original labels and my paralectotype label.".

Diagnosis.

Most similar to A. pallidus and A. raffrayi but separated from these taxa by the presence of distinct interocular spots on head (compare Fig. 4B and D). The metasternal wing is rather narrow; the WC/WS frequency distribution being intermediate between A. pallidus and A. raffrayi, but most similar to A. pallidus (see Table 1, Fig. 12). The aedeagus has an extended portion between the subapical broadening and the apical teeth, and the pronotal hypomeron is not visible in lateral view.

Description.

Habitus as in Fig. 11C, H.

Colour: Head black with rufous anterior area; rufous interocular spots present. Pronotum black with minute to well-defined rufous margin. Elytra ferrugineous to rufopiceous. Ventral surface black, hypomeron rufotestaceous to rufous and epipleuron testaceous to rufotestaceous. Legs rufous to black. Antennae and palpi testaceous.

Microreticulation: Medium impressed on head, pronotum and elytra, and rather similar in both sexes. Composed of a mixture of small and somewhat larger, uneven meshes.

Structural features: Body length: 7.36-8.08 mm (see Table 1). Hypomeron not visible in strict lateral view (as in Fig. 10C, D, compare with 10A, B), lateral bead of pronotum narrow and well defined. Metasternal wing narrow, WC/WS 3.0 or more in most specimens (see Table 1, Fig. 12). Pronotum broad, more than twice as broad as interocular distance (see Table 1, Fig. 13).

Legs: Protarsal claws long,> 1.6 × as long as protarsomere 4 in most specimens (see Table 2, Fig. 14). Metatarsomeres short and broad; metatarsomere 2 <1.8 × as long as broad (see Table 2), metatarsomere 5 <3.3 × as long as broad (see Table 2).

Male genitalia: Subapically broadened and prolonged between the subapical broadening and the apical and subapical teeth (Fig. 8C). Subapical tooth with varying appearance (similar to magnitude in variation seen in Fig. 5A-C).

Female: Externally similar to males.

Distribution.

Kenya, Rwanda, Uganda and the Democratic Republic of the Congo. Nilsson (1992a) and Omer-Cooper (1965) also give South Africa and Zimbabwe but these records are likely to belong to other species (see below).

Habitat.

Most records are from small mountain streams and rivers at elevations of 1900 to 3100 m, but it has also been found in stagnant waterbodies (Nilsson 1992a). We found the species in a very small cold-water forest stream at an elevation of 1900 m in the Taita Hills, Kenya (Fig. 15).

Etymology.

The name refers to the locality where the species was first collected, Mount Ruwenzori.