The millipede tribe Brachyiulini in the Caucasus (Diplopoda, Julida, Julidae) Author Vagalinski, Boyan Institute of Biodiversity and Ecosystem Research at the Bulgarian Academy of Sciences, 2 Yurii Gagarin Street, 1113, Sofia, Bulgaria boyan_vagalinski@excite.com Author Golovatch, Sergei I. Institute for Problems of Ecology and Evolution, Russian Academy of Sciences, Leninsky pr. 33, Moscow 119071, Russia text ZooKeys 2021 2021-08-30 1058 1 127 http://dx.doi.org/10.3897/zookeys.1058.68628 journal article http://dx.doi.org/10.3897/zookeys.1058.68628 1313-2970-1058-1 654932353DDB4E1B8848EAB69F2C20FD 61FB9E86BEE45968AAC868B21AF7ED86 Genus Colchiobrachyiulus Lohmander, 1936 stat. nov. Updated diagnosis. A genus of Brachyiulini differing from contribal genera by the unique arrangement of the gonopod parts, including the promeres being positioned completely laterally rather than anteriorly in relation to the opisthomeres, and the solenomere being protected by specific grooves/channels in the anterior process of the opisthomere and in the distomesal process of the promere; as well as by the following combination of other characters: opisthomere with a lobe-like basoposterior process being mostly fused to CBO, ending with a freely protruding, branched, papillose, apical outgrowth, a well-developed anterior process, partially enveloping the solenomere, and a very slender, tapering solenomere, without any distinct apical structures. General description. Small to medium-sized (L (males) = 15-37 mm) Brachyiulini. Ommatidia present. Ozopores right on or tightly behind pro-metazonal suture at least on more anterior body rings. Epiproct well-developed, from moderately to relatively (not conspicuously) long. Male hypoproct rounded trapezoidal to semi-circular, ventrally with two distal paramedian setae. Male mandibular stipites considerably expanded, broadly rounded, without a distinct anterior/anteroventral corner. Male walking legs ventrally with two well-developed adhesive pads, one each on postfemur and tibia. Penis short and stout, with very short apical lobes and small terminal lamellae. Gonopods: In situ considerably protruding from gonopodal sinus, directed caudoventrad. Promere higher than opisthomere, elongate, bearing a slender distomesal process with a narrow channel connected with a deep distomesal groove on caudal sur face of promere, both designed to envelop the solenomere; median ridge and median groove rather poorly developed; flagellum thin, micro-dentate apically. Opisthomere rather elongate; basoposterior process weakly pronounced, mostly fused to CBO, ending in a finely branched, papillose, freely protruding, apical outgrowth; anterior process long and flattened, partly enveloping the solenomere; an apicoposterior or lateral process, and a mesomeroidal lobe absent; solenomere fine and slender, with a simple tubular structure; with long spiniform filaments along flagellum channel. Vulva: Subcylindrical, mostly symmetrical. Bursa with a distinct, more or less obtuse, postero-apical margin. Opening placed apically on bursa. Operculum subequal in height to bursa. Receptaculum seminis: central tube narrow; posterior tube long and very narrow, somewhat folded; posterior ampulla small to medium-sized. Comment. Vagalinski and Lazanyi (2018) , in their revision of the tribe Brachyiulini , retained Colchiobrachyiulus as a subgenus of Megaphyllum due to its apparent correspondence to the diagnosis of the latter genus. However, the examination of the present material of both C. dioscoriadis (Lignau, 1915), comb. nov. and C. montanus sp. nov. shows that the two species can hardly be regarded as close relatives of Megaphyllum s. str., and the unique arrangement of the gonopodal apparatus alone is sufficient to warrant Colchiobrachyiulus the status of a full genus. Besides this, certain morphological characters of Colchiobrachyiulus suggest proximity to Omobrachyiulus Lohmander, 1936: a lobe-like, basoposterior process of the opisthomere ending in a shield-like, apical outgrowth, branched or dentate at margin, a fine and slender solenomere, and the presence of long, erect and spiniform filaments along the flagellum channel are seen in many species of Omobrachyiulus . Nevertheless, the absence of an opisthomeral mesomeroidal lobe in Colchiobrachyiulus seems to be a sufficiently significant difference from Omobrachyiulus . Remark. Both the distomesal process of the promere and the anterior process of the opisthomere in Colchiobrachyiulus seem to be specially designed for providing protection to the solenomere, enveloping the latter from the lateral and caudo-lateral sides, respectively. It is also possible that one or both of these structures take part in copulation, facilitating the penetration of the solenomere into the vulval opening.