Valid Names Results
Mesophthirus Gao, Shih, Rasnitsyn & Ren, 2019 (
Xylococcidae)
Nomenclatural History
- Mesophthirus
Gao, Shih, Rasnitsyn & Ren
2019: 2.
Type species: Mesophthirus engeli Gao, Shih, Rasnitsyn & Ren
by monotypy and original designation
.
accepted valid name
Remarks
- Systematics: Gao, Shih, Rasnitsyn & Ren (2019) provisionally assigned these specimens from the mid-Cretaceous to the order incertae sedis, stating that they had an unusual combination of features and that evidence “strongly suggest[s] that Mesophthirus was ectoparasitic” on dinosaur feathers. Grimaldi and Vea (2021) concluded that these insects are actually early instar nymphal scale insects and they could not have been parasitic. Their proximity to feathers was a fossilized coincidence unrelated to diet. In 2022, Shcherbakov assigned this genus to the family Xylcoccidae stating that it was similar to the subfamily Xylococcinae, and the Early Cretaceous genus Baisococcus Koteja, 1989), but differs in longer antennae with a more elongated apical segment and the presence of an extremely long seta on the leg distal to the trochanter. In these characters, resembles the subfamily Stigmacoccinae, but in the larvae of the latter, long knobbed setae at the claw base are absent, a pair of long caudal setae is developed, and the anus is displaced to the dorsal side.
- Structure: Mesophthirus crawlers: very small size (smallest ones ca. 150 μm); body oval to oblong, with no constriction between head, thorax, and abdomen; eyes greatly reduced to one large facet; antenna with only 5–6 antennomeres, apical one largest and having at its apex several long setae and one or shorter, thicker ones; tarsomeres reduced to one (not including the pretarsus).
- General Remarks: Detailed descrition and photographs of first-instar nymphs in Grimaldi & Vea (2021)
Keys
Associated References
1 Species
