Isocolus barakus Nastasi 2024, sp. nov.

Isocolus barakus Nastasi sp. nov. urn:lsid:zoobank.org:act: 1EEB77F3-1302-45A7-97A9-1F829EAC8A12 Material examined. One female: INHS Insect Collection 288135. Kyrgyzstan: Chuy, Bulak, 9 km west of Ak-Tuz, 42°52′47″ N, 76°2′13″ E (approximately 42.880, 76.040 in decimal degrees). 2180–3400 m elevation. Collected 26 July 2000, by vacuum. Field code 00-114-03. C. H. Dietrich coll. Etymology. From the Kyrgyz word барак (phoneticized as “barak”), meaning “sheet” or “plate” and referring to the atypical presentation of the pronotal plate in this species. Noun in apposition. Diagnosis. Isocolus barakus can be easily distinguished from other Isocolus species by the pronotal plate, which is incomplete but with the dorsal portion conspicuously defined laterally in I. barakus (Fig. 17) but incomplete and poorly developed in other Isocolus species (see remarks below). The following combination of characters further separates I. barakus from other Isocolus species: Mesoscutum (Fig. 20) entirely reticulate, without perceptible transverse sculpture; female with 13 antennomeres, with F2 conspicuously longer than F1 (Fig. 18) and without placodeal sensilla on F2; facial radiating striae complete and well-defined (Fig. 16); notauli complete(Fig.20);second metasomal tergite without conspicuous setose patch (Fig. 15); second metasomal tergite without punctation. Description of female (Fig. 15). Body 2.1 mm in length. Coloration of head and mesosoma entirely black; metasoma reddish brown. Mandibles reddish brown. Antennae reddish brown, with scape, pedicel, F1, and some apical flagellomeres much darker. Wing veins brown. Legs yellow except coxae, trochanters, and femora brown proximally to yellow distally and apical tarsomeres brown. Head (Fig. 16). In anterior view slightly subtrapezoidal, 1.2× as wide as tall. Sculpture excluding facial radiating striae coriaceous to reticulate throughout. POL:LOL:OOL:DLO in holotype measuring 11:9:11:4. Malar space 0.6× as long as compound eye in anterior view. Facial radiating striae complete, conspicuously impressed and reaching from clypeus to ventral eye margin. Clypeus subtrapezoidal, moderately projecting ventrally over base of mandibles, and with clypeo-pleurostomal lines strongly divergent ventrally. Genae only slightly expanded posterior to eyes. Antennae (Figs. 15; 18). With 13 antennomeres, about two thirds as long as body length. Conspicuous placodeal sensilla present on F3 and following flagellomeres. F1 2.7× as long as wide. F2 2.8× as long as wide; 1.3× as long as F1. Mesosoma (Figs. 17; 19–21). Moderately convex in lateral view. Pronotum coriaceous to reticulate, with some indistinct striation posteroventrally. Pronotal plate incomplete but well developed, with lateral sutures nearly reaching anterior margin of mesoscutum. Mesopleuron sculpture entirely striate. Mesopleural triangle conspicuously impressed, with dense setae throughout. Mesoscutum coriaceous throughout, with sparse, scattered setae. Notauli complete and narrow throughout. Median mesoscutal impression indistinct. Mesoscutellar disc reticulate anteriorly and medially to rugose-reticulate around outer margins. Mesoscutellar foveae conspicuously impressed, apparent as ovate-subrectangular impressions occupying about anterior third of mesoscutellar disc; smooth to rugose within margins; separated by a broad subtriangular area. Metapleural sulcus meeting mesopleuron around medial third. Propodeal carinae conspicuous, apparent as paired subparallel lateral carinae. Wings (Fig. 15). Hyaline and setose throughout. Fore wing with marginal cell open, 2.7× as long as wide, with vein R1 just about meeting wing margin; areolet conspicuous. Distal margins with conspicuous marginal setae. Metasoma (Fig. 15). Slightly longer than combined length of head and mesosoma. Second metasomal tergite without conspicuous setose patch, with only a few scattered setae. Third and following metasomal tergites with dense micropunctation throughout. Biology. Host unknown. Remarks. This specimen would, at first, appear to represent a species of Isocolus Förster, based on the open marginal cell, slightly projecting clypeus, entirely striate mesopleuron, and having 13 antennomeres in females. However, the pronotal plate is conspicuously defined laterally and nearly complete, with the lateral sutures nearly reaching the anterior mesoscutum but not producing a raised plate (Fig. 17, arrows). The strongly defined but incomplete pronotal plate is typical of some Aulacideini, namely Liposthenes and Panteliella (Nieves-Aldrey 2022), but these species vary considerably from I. barakus, particularly in the structures of the face and mesoscutum, among other characters (Nieves-Aldrey 2022). Additionally, the mesoscutum in most Isocolus species exhibits conspicuous raised, transverse sculpture, but this is not the case in I. barakus. As I. barakus does not exhibit obvious synapomorphies among Aulacideini, but rather possesses plesiomorphic characters in a unique combination, we prefer to place it in Isocolus until further revisionary studies can be done. Isocolus barakus does not strongly disagree with general diagnostic characters of Isocolus despite several atypical characters, but the genus has not been recently revised, and the diagnostic characters given in the literature (e.g., Nieves-Aldrey 1994, Melika 2006, Nieves Aldrey 2022) require further validation.