Pachyanthidium (Pachyanthidium) arnoldi Mavromoustakis

(Figs 25–26)

Pachyanthidium cordatum arnoldi Mavromoustakis, 1936: 147, male holotype (TMSA) Zimbabwe. Pachyanthidium (Pachyanthidium) arnoldi Mavromoustakis: Pasteels 1984: 140 –148.

Diagnosis. This species can be distinguished from subgenera other than Pachyanthidium s. str. by the combination of naked eyes and no arolia. From all other members of the subgenus Pachyanthidium it can be distinguished by the black maculations on the metasomal terga and a large, deep pit midventrally on the mesepisternum. In addition, the male can be distinguished by the combination of posterolateral angle of scutum thickened, triangular in lateral view, dorsum of metasoma with black restricted to anterior terga and T7 with a narrow posterolateral spine (narrower than length) and small, acutely pointed, posteromedian spine that scarcely exceeds the lateral spines.

Description. FEMALE. Lengths not recorded. Structure (Fig. 26). Head and mesosoma black with yellow maculation on clypeus, lower paraocular area, narrow outer margin of upper paraocular area, spot on medioventral supraclypeus, spot between median ocellus and clypeus, posterior margin of vertex, anterior margin of gena, base of mandible, lateral margins of scutum and axilla, subapical posterolateral fleck on scutellum, tegula spot, mesepisternum behind omaulus, posterior femur and dorsal tibiae and tarsi (remainder of legs orangish–yellow); metasoma generally black and reddish–orange (possibly originally yellow altered by post–mortem discolouration by cyanide), T1–T5 reddish–orange laterally, black medially, distal margins translucent and about concolorous with anterior region of terga, except T5 entire posterior margin translucent orange, T6 reddish–orange. Structure (Fig. 26). Preoccipital ridge weakly lamellate; eye naked; clypeus ventral edge straight, 2 mediolateral tubercles; mandible not spatulate, with 6 teeth (not peg-like) and no distinct inner tooth; pronotal lobe strongly lamellate; omaulus lamellate; forebasitarsus short and broad, length, 0.6x foretibia length, 3.3x its width; arolia absent; T1–T5 without lateral spines; T6 rounded laterally, slightly lobate, without spine, extended posteriorly, distinctly cleft posteromedially.

MALE. Lengths: head 2.8–3.2 mm; scutum 1.8–2.0 mm; forewing 6.3–6.8 mm; body 6.8–7.7 mm. Colour as in female except mandible entirely yellow, subapical posterolateral patch on scutellum, posterior lamella of scutellum translucent yellowish, metasoma yellowish-orange on anterior T1 (cross-band), dorsolateral T2–T5 (oval), lateral T6, entire T7, S1–S6 distal margins translucent orange. Structure (Fig. 26). Preoccipital ridge weakly lamellate; eye naked; clypeus ventral edge straight, mediolateral tubercle; antennal flagellum 0.79x eye length, 2.8x scape length; mandible 5 dissimilar, pointed teeth; omaulus lamellate; forebasitarsus sparely pubescent, with moderately long posterior fringe; forebasitarsus length 0.6x foretibia length, 0.3x its width, not distinctly extended anterodistally; hind basitarsus wide, length 2.5x width; arolia absent; T1–T4 without lateral spines or swelling; T5 slight posterolateral swelling; T6 one plane, extended posteromedially, ventrolateral spine, posterolateral and posteromedian tubercles, latter emarginated posteromedially; T7 narrow posterolateral spine (narrower than length), acutely pointed, posteriorly median spine, concavity between median and lateral spines twice width of median spine; terminalia as in P. cordatum (cf. Fig. 16).

Distribution. Pachyanthidium arnoldi is only known from Zambia and Zimbabwe (Fig. 25).

Material examined. Type material. Male holotype of Pachyanthidium cordatum arnoldi: ‘ Bulawayo Rhodesia 7 Mar.1912 G. Arnold, Type, Pachyanthidium cordatum (Smith) subsp. arnoldi, Mihi G.Mavromoustakis det., TYPE Hym 1158 Pachyanthidium cordatum arnoldi Mavromoustakis ♀ ’, in TMSA .

Additional material. Zambia. Mfuwe, 6–18km SW, 1995. iii.20–22, W. J. Pulawski (1♂ CAS); Mfuwe, 7km SW, camp at Luangwa River, 1998. iii.7–9, W. J. Pulawski (1♀ CAS) .