Burttia caerulea Hemp sp. nov.

Type material. -

Holotype: Tanzania • male; Nguru Mountains, montane forest above Ubiri, 1740 m; -6.044233°, 37.562823°; February 2021; CCH.

Paratypes: Tanzania • 3 males, 4 females; same data as holotype; CCH.

Diagnosis. -

Burttia caerulea sp. nov. is morphologically very similar to B. sylvatica and thus fits exactly the generic description given by Dirsh (1965). Even the coloration is similar, although males of B. caerulea n. sp. have brighter blue bases of the antennae (Fig. 1). Overall, B. caerulea sp. nov. is larger and stouter than B. sylvatica (Fig. 2). Both species have large, paired tubercles on the supra-anal plate, but while those of B. sylvatica are vertical and rounded, those of Burttia caerulea sp. nov. are pointed towards the rear and more acute. The male supra-anal plate of Burttia caerulea is proportionately shorter than that of Burttia sylvatica, and it has paired longitudinal depressions basally, unlike the single midline depression of Burttia sylvatica (Fig. 6A, B). Other differences are found in the epiphallus (Fig. 5). B. sylvatica has a smaller epiphallus compared to B. caerulea sp. nov. with smaller lophi. On the shoulder between the lophi and the bridge in B. sylvatica, only small humps are present that are roundish and more pronounced in B. caerulea sp. nov. (compare Figs 5, 6F, H). B. sylvatica is endemic to the Uluguru Mountains while B. caerulea sp. nov. is only known from the montane zone in the Nguru Mountains. The linear distance between these mountain ranges is about 100 km.

Etymology. -

From Latin: - caeruleum = blue, because of the blue bases of the male antennae.

Description. -

Male. Body, part of face, and outer sides of knees of hind legs dark brown. Legs creamy to white except for black tarsi and greyish blue hind tibiae. With broad white fascia across face. Bases of antennae blue (Fig. 1A). Antenna about 1.5 times longer than head and pronotum, compressed at base (Fig. 2A). Eyes oval, prominent. Fastigium verticis angular, with apex forming a rostrum, as described for the genus. Frons strongly oblique (Fig. 1A), upper part of frontal ridge strongly protruding in front of eyes, sulcate. Dorsum of pronotum with well-developed median carina (Fig. 3A). Integument of whole body strongly wrinkled (Fig. 2). As described for the genus, prosternal process very pointed with a broad base. No trace of wings. Supra-anal plate elongate with two well-developed tubercles near middle of supra-anal plate (Figs 4A, 6B). Subgenital plate upcurved, with obtuse apex (Figs 4A, 6B). Epiphallus divided, with large complex lophi; ancorae small and inwardly directed (Fig. 5B). Paired post-epiphallic sclerites present. Endophallic structures normal, aedeagus partly sheathed in ectophallic membrane (Fig. 6K).

Female. Larger and stouter than male (Fig. 1A), almost uniformly dark brown, without white fascia on face. As in male, with a median carina on the pronotum (Fig. 3B). Supra-anal plate elongate with a median ridge (Fig. 7A). Valves slender with curved apices, cerci short. Subgenital plate with slightly excurved posterior margin (Fig. 7B, C).

Measurements (mm). -

Males (N = 4): Body length: 15.6-18.0; Medial length of pronotum: 3.1-3.4; length of hind femur: 10.1-10.3. Females (N = 4): Body length: 22.6-22.8; Medial length of pronotum: 4.3-4.5; length of hind femur: 13.0-14.4.

Habitat. -

Along forest edges and in understory vegetation of montane forest, often on the forest floor among litter.

Distribution. -

Tanzania, Nguru Mountains.