Ramitrichophorus Hille Ris Lambers, 1947

Stekolshchikov, Andrey V. & Buga, Sergey V., 2022, Revision of the aphid subgenus Ramitrichophorus Hille Ris Lambers of genus Macrosiphoniella (Hemiptera, Homoptera: Aphididae, Macrosiphini), with redescriptions of all known species and identification keys, Zootaxa 5183 (1), pp. 293-342 : 295-296

Subgenus Ramitrichophorus Hille Ris Lambers, 1947

Type species: Macrosiphoniella (Ramitrichophorus) janckei Börner, 1939

Description. Body elliptical or elongate elliptical. Thorax of apterous morphs with more or less wide bands on pro- and mesonotum. Abdominal dorsum of all morphs weakly sclerotized, with or without small spinal and marginal sclerites, antesiphuncular sclerites and bands on abdominal segments VII and VIII. Setae on body and appendages different types ( Figs. 1–3 ). Marginal and spinal tubercles absent. Head without epicranial suture or very rare with its weak traces. Frontal tubercles weakly developed, median tubercle absent, antennal tubercles visible, but not high, divergent, with a shallow frontal sinus between them, sometimes frons nearly straight. First and second antennal segments slightly wrinkled, almost smooth, 2nd segment ventrally with rare short scales, 3rd–6th segments with large scales which are almost invisible on basal part of 3rd segment and well-defined on 5–6th segments. Antennae 6-segmented, secondary rhinaria are present on third, and sometimes on fourth and fifth antennal segments in all morphs, they round or oval, not large, weakly protuberant and scattered not in a row along one side of the segment almost from basis to apex in case of a large number of rhinaria. Rostrum long. Ultimate rostral segment long and narrow, nail-like—comparatively wide at the very base, tapering just after the base, then almost parallel-sided and pointed at the apex. Legs normal. Chaetotaxy of first tarsal segments 3, 3, 3 (rarely on one leg the first tarsal segment has 2 or 4 setae). Arms of mesosternal furca connected by wide base. Spiracles reniform. Siphunculi subcylindrical, gradually tapering towards apex, rarely slightly curved outwards, with small flange and polygonal reticulation, distinctly imbricated, with short rows of pointed spinules at the base that fused into large scales in front of the reticular part. Subgenital plate oval. Central part of anal plate protruding in the form of tubercle directed downwards. Cauda nearly triangular, with some more or less evident constriction in the middle, which sometimes divides it into broad base and relatively thin, slightly conical and rounded on apex distal part.

Etymology. The name of the subgenus is a compound of word „rami“—plural from Latin „ramus“ (branch), the New Latin word „tricho“ origin from Greek „thrix“ (hair), element „-phor-“—from the Greek verb „phoro“ (carry) and the Latin masculine ending „-us“. This name was given to this subgenus for the presence on the body of individuals of the type species a large number of ramose apically long setae. Gender: masculine.

Diagnosis. The subgenus Ramitrichophorus differs from other subgenera of the genus Macrosiphoniella in the following combination of characters: a long, almost nail-like ultimate rostral segment, triangular, often with a significant constriction in the middle cauda, weakly developed frontal tubercles, with a shallow frontal sinus between antennal tubercles (sometimes frons nearly straight), and location of most of the secondary rhinaria along one side of the third antennal segment.

Several authors considered Ramitrichophorus as an independent genus. So Kadyrbekov (2017) indicates that Ramitrichophorus is „close to the genus Macrosiphoniella Guerc. , but differs from it in the presence of a single rounded protuberance on the anal plate, at least 6 setae on the disc of the genital plate, pointed, forked, tridentate, fanshaped dorsal setae". Therefore Kadyrbekov assigns generic status to Ramitrichophorus . The presence of 6 setae on the disc of the genital plate, as well as setae of the indicated shape, is found in different species of Macrosiphoniella , especially since the shape of the setae in species of Ramitrichophorus is different and the character that separates the species cannot be at the same time a common character of the genus. The anal plate with rounded protuberance, although less pronounced, is found in a number of species Macrosiphoniella . Moreover, this character is not unique within Macrosiphoniella , the anal plate strongly protruding in the form of a tubercle is also found in species of other genera, such as Microsiphum Cholodkovsky, 1902 , Microsiphoniella Hille Ris Lambers, 1947 , and Brevisiphonaphis Stekolshchikov et Qiao, 2008 . The set of characters that distinguish Ramitrichophorus species from other species of the genus Macrosiphoniella does not make the difference between them significant and, in our opinion, is at the level of intrageneric rather than intergeneric differences, which allows us to continue to consider Ramitrichophorus as a subgenus of the genus Macrosiphoniella .

Figures

FIGURES 1–3. Spinal setae on III abdominal segment of apterous viviparous females. 1, Macrosiphoniella (Ramitrichophorus) hillerislambersi; 2, M. (R.) janckei; 3, M. (R.) medvedevi.