Pactopus burmensis, 2019

Muona, Jyrki, 2019, Throscidae (Coleoptera) relationships, with descriptions of new fossil genera and species, Zootaxa 4576 (3), pp. 521-543 : 533-541

Pactopus burmensis new species

Figs. 12–14 , 25

Type material. Holotype labeled: Pactopus burmensis n. sp. / HOLOTYPE /J.Muona des. 10-2015. Second label with following data: 1401-1572 /Burmese amber/LarvaAdult/Throscida 8.5 mm /98.79+-0.62 Ma. Embedded in a

cone-shaped, dark brown Burmese Amber piece, 12 mm x 10 mm x 10 mm, sex unknown. Age 98.79 +/- 0.62 Mya. Numerous unidentified plant remains are present as well ( Fig. 25).

Paratype in a box-shaped piece of fairly lightly coloured Burmese Amber, 12 mm x 6 mm x 6 mm, sex unknown. Age 98.79 +/- 0.62 Mya. Some unidentified plant remains are present as well. Length 2. 9 mm (PT) to 3.0 mm (HT).

Diagnosis. The combination of Throscini type protibiae ( Fig. 12 ), metathoracic and abdominal tarsal grooves and unmodified head is unique among Throscidae and places this species in Pactopus . Pactopus burmensis resembles the extinct P. americanus Wickham in being relatively wide in shape, having strongly bent tarsal grooves on metaventrite and long, straight abdominal tarsal grooves. The extant P. horni Leconte and the Eocene P. fasolti Muona and P. fafneri Muona are more parallel-sided and much narrower than P. burmensis . Pactopus burmensis differs from P. americanus in having the prosernal process widest in the apical third and narrowing both anteriorly and posteriorly and by having the tarsal gooves on metaventrite more abruptly bent and close to parallel to metanepisterna caudally.

Description. Dorsum poorly visible in the holotype, partly clear on the paratype. Elytra without keeled humeri, with sharp striae and slightly convex interstices, punctation poorly visible, but apparently week. Ventrum moderately densely punctate, punctures small. Antennae with slender club, all three apical antennomeres longer than wide. Prosternal process widest in the apical third ( Fig. 13 ). Metaventrite with strongly curved tarsal grooves ( Fig. 13 ), abdominal tarsal grooves long and straight ( Fig. 14 ).

Etymology. Known only from Burmese Amber.

Figures

FIGURE 12. Pactopus burmensis n. sp., front leg.

FIGURE 13. Pactopus burmensis n. sp., ventral view. AtG = abdominal tarsal groove; MtG = metathoracic tarsal groove; PP = prosternal peg.

FIGURE 14. Pactopus burmensis n. sp., abdomen, ventral view. AtG = abdominal tarsal groove.