Tanaostigma Howard, 1890

Noort, Simon van & Copeland, Robert S., 2020, First record of the genus Tanaostigma (Hymenopteraı Chalcidoideaı Tanaostigmatidae) from the Afrotropical region with description of three new species, Journal of Natural History 54 (9), pp. 703-722 : 705-708

Tanaostigma Howard, 1890

Tanaostigma Howard, 1890: 147 – 148 .

Trichencyrtus Ashmead, 1904: 291 ,292,392,495. Type species Trichencyrtus chapadae Ashmead, 1904 , by original designation. Synonymy by LaSalle, 1987.

Type species Tanaostigma coursetiae Howard, 1890 , by monotypy.

Diagnosis. Modified after LaSalle (1987) to incorporate the African species.

Females of the genus Tanaostigma are distinguished from other tanaostigmatids by the following unique characters: head and body with squamiform white setae ( Figures 1 (a,b), 3(a,b), and 5(a,b)); the Oriental species and most New World species have the funicular segments wider than long, except for T. slossonae , but in the three African species the first one or two segments are longer than wide or as wide as long; stigmal vein slender, straight, and perpendicular to the marginal vein in most New World species, but strongly curved and arising at an acute angle to marginal vein in the Neotropical species T. stanleyi , the Oriental T. indica and in all African species ( Figures 1 (f), 3(f), and 5(f)). In all New World and the Oriental species the scape is 1.5 – 2.5 times longer than wide with a flattened ventral expansion, however, this character is seen in many species of Tanaostigmodes Ashmead. In the African species, the scape is more elongate with the ventral expansion reduced and restricted to the distal half of the scape.

Males of New World species have 4 – 5 funicular rami, sometimes the frons has a transverse furrow halfway between torulus and median ocellus. Males are unknown for the Afrotropical and Oriental species.

Generic description. Modified from LaSalle (1987) to incorporate the African species.

Female. Colour usually mostly black to dark brown, sometimes with metallic tinge. Head usually with transverse white to yellow stripe on both face and lower frons, African clade and Oriental species without any stripes on head. Head and body usually with white squamiform setae.

Head surface sculpture usually reticulate to imbricate; scrobal impression shallow, without well-defined margin; inter-antennal projection present and small or absent. Subocular sulcus complete. Antenna with scape 1.5 – 2.5 times longer than wide, with flattened ventral expansion, which may be restricted to distal half. Funicular segments usually all wider than long, except in African clade where they are longer than wide or as wide as long.

Mesosoma dorsally usually reticulate. Notauli usually complete, but may be absent posteriorly in the African species. Scutellum often with lateral glabrate area, absent in African clade. Propodeum variable, often with one or more medial carinae. Mesopleuron usually reticulate. Middle tibia often with longitudinal carina on dorsal margin. Wings usually hyaline, with slender, delicate veins, but fore wing may have modified stouter setae that create patterns or transverse bands. Stigmal vein either straight and perpendicular to postmarginal vein or curved and at an acute angle to postmarginal vein.

Metasoma usually reticulate. Posterior margin of T2-T4 usually with medial incision, absent in African clade, except for indication on T2. Ovipositor slightly exerted.

Male (unknown in African species). Antenna with 4 – 5 long funicular rami. Funicular segments increasing in length distally. F6 longest funicular segment in species with five rami, shorter than F 5 in species with four rami. Frons often with transverse furrow about halfway between torulus and median ocellus.

Affinities

Tanaostigma is still poorly defined, with the white squamiform setae, and wider than long and laterally compressed funicular segments proposed as synapomorphies defining the genus ( LaSalle 1987). However, two species, T. glabrum and T. impilum , do not have squamiform setae, hypothesised to be a character state reversal ( LaSalle 1987) and T. slossonae has funicular segments that are not flattened and are subequal in length. In terms of antennal morphology, the African species are most similar to this species, rendering the former character state of compressed antennal segments as of no use in defining the genus. LaSalle (1987) provides a detailed discussion of generic concepts and delimitation.

Distribution. Afrotropical, Nearctic, Neotropical and Oriental regions. Afrotropical records: Kenya, South Africa. Neotropical records: Argentina, Bahamas, Brazil, Colombia, Costa Rica, Cuba, Dominican Republic, Mexico, Puerto Rico, Trinidad and Tobago, Venezuela. Nearctic records: USA. Oriental record: India.

Biology of Tanaostigmatidae . Phytophagous, usually associated with galls, presumed to be the primary gall-former ( LaSalle 1987, 2005). Exceptions include some Indian Tanaostigmodes species that are seed predators without gall formation ( Lateef 1977; Lateef et al. 1985), and some Brazilian and Japanese Tanaostigmodes species develop as inquilines in cecidomyiid galls ( Fernandes et al. 1987; LaSalle 1987), others are parasitoids of gall-forming cynipids ( Tachikawa 1973, 1978; LaSalle and Noyes 1985; LaSalle 1987). Gall formers usually attack woody trees and shrubs of the family Fabaceae (= Leguminosae), a few attack species of Polygonaceae , Rhamnaceae , or Myrtaceae , forming galls on stems, leaves, seeds, or in flowers (usually in deformed ovaries) ( LaSalle 1987; Gupta & Joshi, 2016).

Host plant records for the Neotropical Tanaostigma species are as follows: Acacia constricta ( T. stanleyi ); Aeschynomene petraea var. madrensis ( T. lobo ); Canavalia ensiformis ; Cratylia moelis , Inga species ( T. gahani ); Galactia striata ; Galactia volubilis ( T. slossonae ); Haematoxylon brasiletto ( T. haematoxyli ); Haematoxylon campechianum ( T. haematoxyli ); Lonchocarpus latifolia ( T. coursetiae ); Machaerium robinifolium ( T. bennetti ); Machaerium ( T. chapadae ); Prosopis strombulifera ( T. albosquamatum ); Willardia mexicana ( T. coursetiae ) ( LaSalle, 1987); the Oriental species T. indica was collected from a container containing Millettia (= Pongamia ) pinnata (L.) Panigrahi ( Fabaceae ) leaves infested with galls ( Gupta and Joshi 2016). Biology of the Afrotropical species is unknown.

Key to Afrotropical species of Tanaostigma

1. Fore wing with broad brown central infuscation (a); propodeum with complete medial longitudinal carina (b); axillar grooves meet at trans-scutellar sulcus (b); hind femur and fore tibia all black ............................. ............................. T. lasallei sp. nov. - Fore wing with narrow transverse band of dark setae (a); propodeum either without carina or with the medial longitudinal carina only present anteriorly for a very short distance (b); axillar grooves meet trans-scutellar sulcus independently (b); hind femur and fore tibia with distal end orangish-brown ........................................................ 2

2. Fore wing band with fewer, more pale, and less densely distributed setae (a); fore wing twice as long as wide (a); postmarginal vein as long as stigmal vein (a); squamiform white setae stouter and individually more widely spaced on head (b) and other areas of the body; mesopleuron with coarse reticulate sculpturing (c); metanotal trough with three large metanotal fovea, not extending medially beyond small central metanotal fovea ........................................................................ T. mulu sp. nov. - Fore wing band with numerous dark, densely distributed setae (a); fore wing 2.5 times as long as wide (a); postmarginal vein shorter than stigmal vein (a); squamiform white setae more elongate and densely distributed on head (b) and other areas of the body; mesopleuron with finer, more numerous reticulate sculpturing (c); metanotal trough with a single large metanotal fovea laterad of small central fovea, with narrow elongate fovea anteriorly situated, with three pit-like fovea present medially of central metanotal fovea.................................. T. ukumbusho sp. nov.

Figures

Figure 1. Tanaostigma lasallei Holotype female. (a) Habitus, lateral view (b) Habitus, dorsal view (c) Head and mesosoma, lateral view (d) Head and mesosoma, dorsal view (e) Head, anterior view (f) Wings (inset: data labels).

1. Fore wing with broad brown central infuscation (a); propodeum with complete medial longitudinal carina (b); axillar grooves meet at trans-scutellar sulcus (b); hind femur and fore tibia all black ............................. ............................. T. lasallei sp. nov. - Fore wing with narrow transverse band of dark setae (a); propodeum either without carina or with the medial longitudinal carina only present anteriorly for a very short distance (b); axillar grooves meet trans-scutellar sulcus independently (b); hind femur and fore tibia with distal end orangish-brown ........................................................ 2

2. Fore wing band with fewer, more pale, and less densely distributed setae (a); fore wing twice as long as wide (a); postmarginal vein as long as stigmal vein (a); squamiform white setae stouter and individually more widely spaced on head (b) and other areas of the body; mesopleuron with coarse reticulate sculpturing (c); metanotal trough with three large metanotal fovea, not extending medially beyond small central metanotal fovea ........................................................................ T. mulu sp. nov. - Fore wing band with numerous dark, densely distributed setae (a); fore wing 2.5 times as long as wide (a); postmarginal vein shorter than stigmal vein (a); squamiform white setae more elongate and densely distributed on head (b) and other areas of the body; mesopleuron with finer, more numerous reticulate sculpturing (c); metanotal trough with a single large metanotal fovea laterad of small central fovea, with narrow elongate fovea anteriorly situated, with three pit-like fovea present medially of central metanotal fovea.................................. T. ukumbusho sp. nov.