Agabus sjostedti 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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scientific name	Agabus sjostedti Regimbart , 1908
status

Treatment

Agabus sjostedti Regimbart, 1908 Figures 1 View Figure 1 , 4C View Figure 4 , 8A View Figure 8 , 10A View Figure 10 , 11A View Figure 11 , 11F View Figure 11 , 12 View Figure 12 , 13 View Figure 13 , 14 View Figure 14

Agabus sjostedti Régimbart, 1908: 5-6

Type locality.

"mont Meru, entre 3,500 et 4,300 mèt” [Tanzania, Mount Meru, between 3500 and 4300 m].

Type material.

Lectotype ♂ (NHRS) labelled: "Meru Regenwald", "Meru Sjöstedt”, “Type”, “Typus”, " Agabus sjöstedti Rég. n.sp. ♂ et ♀ "LECTOTYPUS ♂ Agabus sjostedti Régimbart 1908, Des. A.Nilsson -90". Paralectotypes 2 ♂ 1 ♀ (NHRS) labelled: "Meru Regenwald", "Meru Sjöstedt”, "22 dec", "PARALECTOTYPUS ♂/♀ Agabus sjostedti Régimbart 1908 Des. A.Nilsson 1990".

Diagnosis.

Most similar to A. dytiscoides but separated by its larger size (see Table 1 View Table 1 ), narrower metasternal wing (see Table 1 View Table 1 ), broader prontoum (see Table 1 View Table 1 and compare Fig. 4C View Figure 4 with Fig. 4A View Figure 4 ) and by the curvature of the aedeagal subapical tooth (compare Fig. 8A View Figure 8 with Fig. 8B View Figure 8 ). The aedeagus is prolonged preapically as in the preceeding three species, but the pronotal hypomeron is clearly visible in strict lateral view (see Fig. 10A View Figure 10 ).

Description.

Habitus as in Fig. 11A, F View Figure 11 .

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

Microreticulation : Males with medium impressed reticulation on head and pronotum and slightly finer reticulation on elytra giving a shiny appearance, all meshes being a mix of smaller and somewhat larger meshes.

The two females studied varied greatly in microreticulation, but shared having mostly isodiametric meshes on elytra and the same variable meshes on head and pronotum as males. One female (Mt. Meru) had very coarse meshes; giving head, pronotum and elytra a matte appearance while the other female (Kilimanjaro Bismarck hut) had the same shiny appearance as males.

Structural features : Body length: 8.08-9.12 mm (see Table 1 View Table 1 ). Hypomeron broadly visible in strict lateral view (see Fig. 10A View Figure 10 ), lateral bead of pronotum broad and well defined (see Fig. 10A View Figure 10 ). Metasternal wing very narrow, WC/WS> 3.6 in most specimens (see Table 1 View Table 1 , Fig. 12 View Figure 12 ). Pronotum broad, more than twice as broad as interocular distance (see Table 1 View Table 1 , Figs 5C View Figure 5 , 13 View Figure 13 ).

Legs: Protarsal claws short, <1.4 × as long as protarsomere 4 (see Table 2 View Table 2 , as in Figs 3A View Figure 3 , 14 View Figure 14 ). Metatarsomeres long and slender; metatarsomere 2> 1.6 × as long as broad (see Table 2 View Table 2 ), metatarsomere 5> 3.3 × as long as broad in most specimens (see Table 2 View Table 2 ).

Male genitalia: Subapically broadened, and prolonged between the subapical broadening and the apical and subapical teeth. Subapical tooth robust, with distinct curvature (see Fig. 8A View Figure 8 ).

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

Distribution.

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

Habitat.

Régimbart (1908) reports that the type specimens (from Mt. Meru) were found in very cold water, at an altitude of 3500 to 4300 m. On Mt. Kilimanjaro it has been found at lower altitudes between 2200 and 3100 m ( Nilsson 1992a).

Etymology.

The name refers to the collector of the type specimens, Yngve Sjöstedt.

Comments.

Nilsson (1992a) studied the material collected by G.F. De Witte and concluded that the animals that Gschwendtner (1938) and Guignot (1959) referred to as Gaurodytes sjostedti from Park National Albert [=Virunga NP in DRC], bordering the Ruwenzori mountains, were in fact A. ruwenzoricus . Older records of A. sjostedti must be interpreted with caution.