Valid Names Results

Mesophthirus engeli Gao Shih, Rasnitsyn & Ren, 2019 (Xylococcidae: Mesophthirus)

Nomenclatural History

• Mesophthirus engeli Gao Shih, Rasnitsyn & Ren 2019: 2. Type data: MYANMAR: Kachin Province (Hukawng Valley) of northern Myanmar, mid-Cretaceous in amber. Holotype, fossil, by monotypy and original designation Type depository: Beijing: Capital Normal University, Key Lab of Insect Evolution and Environmental Changes; accepted valid name Notes: Initially described in order Incertae sedis, Family Mesophthiridae (as a fossil louse) Illustr.

Common Names

Ecological Associates

Geographic Distribution

Keys

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.
• Structure: These crawlers are 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). Other features that are consistent with coccoid crawlers are: wingless, dorsoventrally flattened, thorax well developed, with large prothorax (features common throughout nymphal hemimetabolan insects); the last antennomere with “irregular crinkling” (common in paraneopterans, to which Hemiptera, barklice, true lice, and thrips belong); legs short and stout. The structures described as spiracles by the original authors appear to be small cuticular plates bearing minute setae, which are commonly seen in a serial row on each lateral margin of coccoids. (Grimaldi & Vea, 2021)
• General Remarks: Detailed descripton, photographs and illustrations in Grimaldi & Vea (2021)

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