Agabus dytiscoides Regimbart , 1908

Englund, William F., Njoroge, Laban, Bistroem, Olof, Miller, Kelly B., Bilton, David T. & Bergsten, Johannes, 2020, Taxonomic revision of the Afrotropical Agabus raffrayi species group with the description of four new species (Coleoptera, Dytiscidae), ZooKeys 963, pp. 45-79 : 45

publication ID	https://dx.doi.org/10.3897/zookeys.963.53470
publication LSID	lsid:zoobank.org:pub:9636C9F2-C6BD-4B34-BCC6-ED214C7B0D19
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treatment provided by	ZooKeys by Pensoft
scientific name	Agabus dytiscoides Regimbart , 1908
status

Treatment

Agabus dytiscoides Regimbart, 1908 Figures 1 View Figure 1 , 3A View Figure 3 , 4A View Figure 4 , 8B View Figure 8 , 10B View Figure 10 , 11B View Figure 11 , 11G View Figure 11 , 12 View Figure 12 , 13 View Figure 13 , 14 View Figure 14

Agabus dytiscoides Régimbart, 1908: 6-7

Type locality.

"Kiboscho, au Kilimandjaro … entre 3,000 et 3,500 mèt.” [Tanzania, Kiboscho, Mount Kilimanjaro, between 3000 and 3500 meters].

Type material.

Lectotype ♂ (NHRS) labelled: "Kilimandj. Sjöstedt”, "Kiboscho 3' -4000 m.", "20 febr", "LECTOTYPUS ♂ Agabus dytiscoides Régimbart 1908 Des. Nilsson 1990". Paralectotypes 5 ♂ 3 ♀ (NHRS) labelled: "Kilimandj. Sjöstedt”, "Kiboscho 3' -4000 m.", "20 febr", "PARALECTOTYPUS ♂/♀ Agabus dytiscoides Régimbart 1908 Des. Nilsson 1990".

Diagnosis.

The very narrow pronotum, distinctly narrower than the base of elytra, is characteristic and separates A. dytiscoides from all other species in the group (see Table 1 View Table 1 , Fig. 4A View Figure 4 ). With the pronotal hypomeron clearly visible in strict lateral view (see Fig. 10B View Figure 10 ), A. dytiscoides is most similar to A. sjostedti but can be separated, apart from the pronotal shape, by its smaller size (see Table 1 View Table 1 ), broader metasternal wing (see Table 1 View Table 1 ), and by the shape of the less robust aedeagal subapical tooth (compare Fig. 8A, B View Figure 8 ).

Description.

Habitus as in Fig. 11B, G View Figure 11 .

Colour: Head rufopiceous to black with testaceous to rufous interocular spots. Pronotum rufopiceous to black with testaceous margins; some specimens with two diffuse rufous to testaceous spots in the middle of the pronotum. Elytra ferruginous to brown. Ventral surface rufopiceous to black, hypomeron and epipleuron testaceous. Legs rufous. Antennae and palpi testaceous.

Microreticulation : Males with medium impressed reticulation on head and pronotum. Females with much coarser meshes than males, giving pronotum and elytra a matte appearance. Females also with mostly elongate meshes on pronotum. Males with a mixture of small and somewhat larger meshes on both pronotum and elytra, while female elytra tends to have more uniform small meshes. Both sexes with overall larger meshes on pronotum than elytra.

Structural features : Body length: 7.36-7.76 mm (see Table 1 View Table 1 ). Pronotal hypomeron broadly visible in strict lateral view (see Fig. 10B View Figure 10 ), lateral bead of pronotum well defined. Metasternal wing relatively broad, WC/WS <3.6 (see Table 1 View Table 1 , Fig. 12 View Figure 12 ). Pronotum very narrow, <2.0 × as broad as interocular distance (see Table 1 View Table 1 , Figs 4A View Figure 4 , 13 View Figure 13 ), clearly narrower than base of elytra and therefore with a non-continuous outline between pronotum and elytra.

Legs: Protarsal claws short, <1.6 × as long as protarsomere 4 (see Table 2 View Table 2 , Figs 3A View Figure 3 , 14 View Figure 14 ). Metatarsomeres very long and slender; metatarsomere 2> 1.8 × as long as broad (see Table 2 View Table 2 ), metatarsomere 5> 3.6 × as long as broad (see Table 2 View Table 2 ).

Male genitalia: Subapically broadened, and prolonged between the subapical broadening and the apical and subapical teeth. Subapical tooth with curvature as in Fig. 8B View Figure 8 , less robust than in A. sjostedti .

Female: Elytral and pronotal microreticulation much coarser than in males.

Distribution.

Known from Kilimanjaro and the Loolmalasin mountains in northern Tanzania (see Fig. 1 View Figure 1 ).

Habitat.

Régimbart (1908) reports that the type specimens were found in cold runoff water from a glacier at 3000 to 3500 m.

Etymology.

The name literally translates to " Dytiscus -like". In his original description Régimbart (1908) explains that “J’ai donné à l’ A. dytiscoides ce nom à cause de la grande similitude de forme et de couleur des males dans les deux especes. [I gave it the name A. dytiscoides because of the great similarity in form and colour between the males in the two species.]". Despite great differences in size and many other characters, the pale pronotal margins and the distinct shoulder between the pronotum and elytra are somewhat reminiscent of a Dytiscus . That said, Régimbart also mentioned similarities with A. raffrayi , making it difficult to be sure exactly what he was referring to in choosing this name.