Lithohypna Nikolajev, Wang

Wang, Bo & Zhang, Haichun, 2011, A new fossil genus of the family Glaphyridae (Coleoptera: Scarabaeoidea) from the Lower Cretaceous Yixian Formation, Zootaxa 2811, pp. 47-52 : 48

Genus Lithohypna Nikolajev, Wang , & Zhang, new genus

Type species. Lithohypna chifengensis new species here designated.

Etymology. The name is derived from lithos, which is Greek for stone, and the generic name Anthypna Eschoscholtz, 1818 . Gender: feminine.

Diagnosis. Winged. Body elongate, length about 15 mm. Labrum large, approximately twice as wide as long, somewhat bilobed, sinuate in the middle. Clypeus with truncate, straight apical margin. Scutellum exposed, Ushaped. Elytra elongate, without striae, dehiscent at apex. Elytral lateral margin arcuate. Pygidium visible beyond elytra. Mesocoxae moderately separated. Mesofemur narrow. Protibia with three large denticles on the outer margin. Protarsus longer than protibia, non-lamellate medially. Metatibia with single, transverse carina on the outer margin.

The key differences between Lithohypna and other Glaphyridae genera is given in the table 1.

1 2 3 4 5 6 7 8 9 10 11 Anthypna Eschscholtz, 1818 b b b b a a c a a b a Amphicoma Latreille, 1807 b a b b-c a b b b a b a Cretoglaphyrus Nikolajev, 2005 a ?? b a c?? a a b a Eulasia Truqui, 1848 b b b b a a b a a b a Glaphyrus Latreille, 1807 a b b a a-b b a a b a a-b Lichnanthe Burmeister, 1844 b a a b a a a a a a a Lithohypna Nikolajev, Wang , & a b a b a a?a a a a c Zhang, 2011

Pygopleurus Motschulsky, 1860 b b b a a a c a a b a

1. Mesoepimeron: a—clearly visible from above between pronotum and elytron; b—completely covered by elytra and not visible from above.

2. Antennal club: a—second antennomere free (antennal club usually elongate); b—second antennomere partially enclosed by the first antennomere (antennal club usually short).

3. Labrum: a—about 2.2 times wider than long; b—about 4–6 times wider than long.

4. Scutellum: a—triangular; b—U-shaped and broad; c—U-shaped and narrow.

5. Elytron: a—without longitudinal carinae; b—with low and wide longitudinal carinae; c—with sharp and thin longitudinal carinae.

6. Protibia: a—shorter than protarsus ( Fig. 7 ); b—longer than protarsus.

7. Protarsus: a—tarsomeres 1–4 unmodified ( Fig. 7 ); b—tarsomeres 1–4 lamellate on inside ( Figs. 1–2 ); c—tarsomeres pectinate on inside ( Figs. 3–4 ).

8. Mesotibia: a—apex unmodified; b—apex lamellate ( Fig. 5 ).

9. Metafemur: a—slender; b—wide.

10. Lateral margin of metatibia: a—with one carina; b—without carinae.

11. Apex of metatibia: a—unmodified; b—with immobile spur; c—lamellate, like apex of mesotibia of Amphicoma species (see Fig. 5 ).

Composition. Only the type species is known.

Remark. Lithohypna characters may be a complex of plesiomorphies, synapomorphies and autapomorphies. Characters such as a large labrum, long protarsus with unmodified tarsomeres 1–4 in males, and unmodified apex of mesotibia in males are likely plesiomorphic. The mesoepimeron being clearly visible from above is a possible synapomorphy with the genera Glaphyrus and Lichnanthe . The antennal club with second antennomere partially enclosed by the first antennomere is a possible synapomorphy with the genera Anthypna , Eulasia , and Pygopleurus . Undoubtedly, the modified apex of the metatibia in males is an autapomorphy. A phylogenetics analysis will be needed to determine if the genus Lithohypna is a sister group to any of the extant taxa of the same rank. The Mesozoic genus Cretoglaphyrus might also be a sister group to Lithohypna as Cretoglaphyrus has characters such as a short upper lip (autapomorphy or possible synapomorphy with the extant Glaphyridae genera) and an unmodified apex of the mesotibiae and metatibiae in males (possible plesiomorphies). Until a thorough phylogenetic analysis provides better evidence for evolutionary relationships among Glaphyridae taxa, the genus Lithohypna should be considered as incertae sedis and not placed in any of the Glaphyridae subfamilies.

Figures

FIGURES 1 – 7. Extant Glaphyridae genera, leg features: 1 – 2 — Amphicoma, protarsus [1 — A. fairmairei (Semenov), 2 — A. latouchei (Fairmaire)]; 3 — Eulasia, protarsus of E. (Solskiola) analis (Solsky); 4 — Pygopleurus, protarsus of P. vulpes (Fabricius); 5 — Amphicoma, mesotibia apex of A. latouchei (Fairmaire); 6 – 7 — Glaphyrus festivus Ménétriés (6 — mesotibia apex, 7 — proleg) (after Medvedev [1960]).