Tachytes nigroannulatus Bischoff

Tachytes nigroannulatus Bischoff, 1913 c:69, ♂. Holotype: ♂, Zimbabwe: Springvale (ZMHU), examined. – R. Turner, 1917:42 (in revision of Afrotropical Tachytes; Zimbabwe; as nigroannulata); Arnold, 1923a:152 (as junior synonym of Tachysphex syriacus Kohl, 1888 = T. albocinctus (Lucas, 1849)), 1927:117 (valid species), 1930:5 (in checklist of Afrotropical Sphecidae); R. Bohart and Menke, 1976:266 (in checklist of world Sphecidae).

Tachytes glabriusculus Arnold, 1923b:209, ♂ (as glabriuscula, incorrect original termination). Syntypes: Zimbabwe: Victoria Falls, Sawmills (SAM, TMP). Synonymized with Tachytes nigroannulatus by Arnold, 1927:117

NOMENCLATURAL HISTORY. — Arnold thought in 1923 that Tachytes nigroannulatus was a junior synonym of Tachysphex syriacus Kohl, 1888 (i.e., of T. albocinctus (Lucas, 1849)), but in 1927 and 1930 he treated it as a valid species, apparently without seeing the type. Having examined the holotype of T. nigroannulatus in 2019, I can confirm Arnold’s opinion of 1927.

RECOGNITION CHARACTERS. — Tachytes nigroannulatus is a small species (female length 7.1-10.2 mm, male length 6.7-8.7 mm), with the galea about as long as wide (markedly shorter than the scape), the thorax, propodeum, and gaster black, gastral terga I-IV with silvery fasciae (setae of tergum V black), and the palpal formula 6 + 4. It differs from most of its African congeners, in particular from T. niloticus R. Turner, in lacking erect setae on the scape (a previously unobserved feature). T. dilaticornis R. Turner and T. pygmaeus shares this character, but both of them are very different. The first of these species has the tergal setae golden, including tergum V (among other differences), and the second differs in having the propodeal enclosure glabrous and the gaster ferruginous at least basally (among other differences). Other characters of T. nigroannulatus include: punctures of postocellar area minute, close to each other (a few punctures larger than most); wing membrane hyaline; erect setae absent on female hindfemoral venter and sternum II; width of male clypeal lamella greater than distance between lamella and eye margin; dorsal length of flagellomere I 1.5-1.7 × apical width in female, 1.3-1.5 × in male. The color of hindfemur and of all tibiae varies from black to ferruginous.

GEOGRAPHIC DISTRIBUTION (Fig. 6).— Tachytes nigroannulatus was known from Zimbabwe only. In reality, it also occurs in Kenya, Namibia, South Africa, and Tanzania.

RECORDS (except for the holotype of Tachytes nigroannulatus, all the specimens recorded are from the California Academy of Sciences collection).

KENYA: Rift Valley Province: Marich Pass Field Studies Centre at 1°32.2ʹN 35°27.4ʹE (7 ♀, 2 ♂).

NAMIBIA: Karibib District: 43 km E Karibib (1 ♂), Khan River 23 km N Karibib at 21°47ʹS 15°57ʹE (1 ♀). Kavango District: 100 km SW Rundu (1 ♂). Okahandja District: Waldau River 17 km W Okahandja at 21°57ʹS 16°45ʹE (4 ♂). Otjiwarongo District: 3 km NE Kalkfeld (1 ♂), 18 km NE Kalkfeld at 20°45ʹS 16°16ʹE (1 ♀). Rehoboth District: 9 km S Rehoboth (1 ♂). Tsumeb District: 30 km E Namutoni (1 ♂), 10 km SE Tsumeb (3 ♂).

SOUTH AFRICA: Free State: Sandveld Nature Reserve at 27°40ʹS 25°41ʹE (2 ♀, 3 ♂). Gauteng: Pretoria Botanical Garden at 25°44ʹS 28°16ʹE (1 ♂).

TANZANIA: Mara Region: Seronera in Serengeti National Park (1 ♂). Morogoro Region: 3 km S Mikumi at 7°25.6ʹS 36°59.1ʹE (2 ♀, 1 ♂). Tanga Region: 2 km NE Mkomazi at 4°37.8ʹS 38°05.5ʹE (4 ♀).

ZIMBABWE: Bulawayo: Umguza River at 20°05ʹS 28°37ʹE (1 ♀), Charara 20 km ESE Kariba at 16°33ʹS 28°58ʹE (1 ♂), Kami (= Khami) Ruins at 20°09ʹS 28°26ʹE (1 ♀, 1 ♂), Kariba at 16°32ʹS 28°49ʹE (1 ♀, 6 ♂), 11 km NE Nyamandhlovu at 19°48ʹS 28°16ʹE (2 ♀, 1 ♂), Redbank at Kami River at 20°00ʹS 28°22ʹE (2 ♂), Sawmills at Umguza River at 19°35ʹS 28°02ʹE (1 ♀), Springvale (1 ♀, ZMHU, holotype of Tachytes nigroannulatus), Victoria Falls at 17°56ʹS 25°50ʹE (2 ♀, 5 ♂).