Rhizoterus vacca Hartig, 1841

Brunet, Bryan M. T., Raupach, Michael J., Rehage, Heinz-Otto, Havill, Nathan P. & Foottit, Robert G., 2023, Discovery of the primary aphid (Hemiptera: Aphidomorpha) and scale insect (Hemiptera: Coccomorpha) type specimens from the collection of Theodor Hartig (1805 - 1880), Zootaxa 5369 (1), pp. 89-116 : 96-97

Rhizoterus vacca Hartig, 1841

Rhizoterus vacca Hartig, 1841: 363 . HOLOTYPE: (1244 [3.02]).

Forda formicaria von Heyden, 1837 (senior synonym— Kaltenbach, 1843: 209). Valid Specimen. One aptera mounted on a point. A second point on the same pin has a damaged specimen (possibly Formica rufa Linnaeus, 1761 see below). Collected from anthills and ants into alcohol by Wilhelm Saxesen in April 1839 from an unknown location.

Remarks. There is some uncertainty around the identity of the aphid specimen. The antennae of this species were illustrated in Hartig (1841, Fig. 13) and therein depicted in a manner consistent with the current use of the name Forda formicaria von Heyden, 1837 in that they are five segmented with the third segment similar in length to the fourth and fifth combined. However, high resolution photographs of specimen 1244 show what appears to be six-segmented antennae with antennal segment III of similar length to IV. Given the contradictory information, the identity of the specimen remains uncertain. If not F. formicaria it may be that the specimen instead represents a species in the genus Paracletus von Heyden, 1837 which have six segmented antennae but otherwise resemble F. formicaria . Confirmation of the synonymy is needed.

Hartig’s notes indicate that the genus was believed to be Rhizobius Burmeister, 1835 [= Prociphilus Koch, 1857 ], and are consistent with Hartig’s (1841) description which indicates that the specimen was collected together with F. rufa by Saxesen and resembled Rhizobius pini Burmeister, 1835 .