Xenocaucus nguru, Weirauch & Forthman & Grebennikov & Baňař, 2017

Weirauch, C., Forthman, M., Grebennikov, V. & Baňař, P., 2017, From Eastern Arc Mountains to extreme sexual dimorphism: systematics of the enigmatic assassin bug genus Xenocaucus (Hemiptera: Reduviidae: Tribelocephalinae), Organisms Diversity & Evolution (New York, N. Y.) 17 (2), pp. 421-445 : 439-440

Xenocaucus nguru , n. sp.

Figures 3 , 5 , 6 , 7 , 9 , 10 .

Diagnosis Female: recognized by the small medium size (∼ 2.5 mm), the distinct lateral setal tufts on head ( Figs. 3 and 6 ), the slightly raised and transversally elongate pronotal disk, the pronotum longer than the mesonotum ( Fig. 3 ; ratio 1.5), the intersegmental membrane between tergites 7 and 8 straight ( Fig. 3 ), and mediotergites 1/2 and 3 glabrous ( Fig. 3 ). Description Female: total length: 2.48 mm, total length: greatest abdominal width 1.9; wing condition and general vestiture as in generic description. Coloration: uniformly yellowish brown to reddish brown. Structure: head: about as long as wide in dorsal view, with very small anteocular area, glabrous area on vertex circular, longitudinal sulcus extending about 1/2 of glabrous area, tuft distinct, lateral fringes longer laterally than around posterior half of head. Antenna: scape length: head length 1.6, moderately slen- der. Labium: first visible segment: head length 0.7. Thorax: transverse suture between pronotum and mesonotum distinct, pronotal disk slightly raised and transversally elongate, pronotum longer than mesonotum (ratio 1.5), greatest pronotal width: pronotal length 1.4. Legs: foretrochanter without ventral process, forefemur length: body length 0.3, forefemur fairly slender. Abdomen: slightly longer than wide, length: width 1.2, intersegmental membrane between tergites 3 and 4 straight, intersegmental membrane between tergites 6 and 7 slightly curved anteriad, intersegmental membrane between tergites 7 and 8 straight, mediotergites 1/2 and 3 glabrous, setae on lateral margin of dorsal laterotergites short, setae dorsally on dorsal laterotergites short. Genitalia: as in generic description.

Male: unknown. Immatures with wing pads suggest that males are macropterous.

Immatures: as in Fig. 3 .

Etymology: named for the holotype locality, Nguru Mts. in Tanzania.

Material examined: holotype: Tanzania Nguru Mts. at Mhonda , 6.10611° S, 37.54389° E, 967 m, 4 Jan. 2012, V. Grebennikov, 1;female (00020629) ( CNC) . Paratypes: Tanzania: Morogoro: Nguru Mts. at Turiani , 6.10667° S, 37.53° E, 1236 m, 5 Nov. 2010, V. Grebennikov, 1;female (00117766) ( CNC) . Nguru Mts. at Mhonda , 6.10611° S, 37.54389° E, 967 m, 4 Jan. 2012, V. Grebennikov, 2;female (00020631, 00020632) ( CNC) , 2;female (00020633, 00020634) ( MMBC), 2;female (00020635, 00020636) ( UCR), 2;female (00020637, 00020638) ( USNM). Other specimens examined: Tanzania: Manyara: Mt. Hanang , NE slope, 4.43058° S, 35.41616° E, 2275 m, 16 Dec. 2012, V. Grebennikov, 1;juvenile male, (00117774) ( CNC) . Nguru Mts. at Mhonda , 6.10611° S, 37.54389° E, 967 m, 4 Jan. 2012, V. Grebennikov, 9;juvenile (00020621– 00020628, 00020630) ( CNC) .

Notes This species is morphologically similar to X. schoutedeni and recovered as its sister species in the molecular phylogeny. It is clearly divergent from that species in the molecular phylogram ( Fig. 1 ) and is morphologically distinguished by the head setation, shape of the pronotal disk, ratio of the pronotum to mesonotum, the shape of the intersegmental membrane 7 and 8, and the setation of mediotergites 1/2 and 3.

Figures

Fig. 3 Dorsal habitus of X. chomensis, n. sp., (female, unsexed immature, and male immature), X. ethiopiensis, n. sp., (male holotype and female), X. kimbozensis, n. sp., (female, unsexed immature, and male immature), the female holotype of X. mancinii, and X. nguru, n. sp., (female, unsexed immature, and male immature). dld setae dorsally

Fig. 5 Lateral habitus of females of the seven East African species of Xenocaucus and the male of X. ethiopiensis. fl flagellomeres, lb1–3 first, second, and third visible labia segments, om ommatidium, pd pedicel; scale bars, 1 mm

Fig. 6 Ventral habitus of the seven East African species of Xenocaucus and the male of X. ethiopiensis; abbreviation: vptr, ventral process on trochanter

Fig. 7 Details of the head (dorsal, lateral, and/or ventral view) of selected species of Xenocaucus

Fig. 9 Scanning electron micrographs of females of X. chomensis (UCR_ENT 00020646; a, b, d, h, i) and X. nguru (UCR_ENT 00020634; c, e, f, g, j, k). a Head, dorsal view; b head closeup, dorsal view; c head and thorax, lateral view; d head, lateral view; e head and

Fig. 10 Distribution of East and West African species of Xenocaucus (top) with a close-up of collecting localities of the species occurring in Tanzania (bottom). The stippled lines indicate disjunct collecting localities for X. kimbozensis, n. sp., and X. nguru, n. sp.

Fig. 1 Best maximum likelihood tree based on three gene regions (16S, 18S, 28S D2 and 28S D3–5; 3060 bp alignment) and 14 ingroup terminals representing the seven currently known East African species of Xenocaucus and ten outgroup taxa; Xenocaucus is recovered as