Cyphochilus Waterhouse, 1867

Sabatinelli, Guido, 2020, Taxonomic notes on the genus Cyphochilus Waterhouse, 1867 (Coleoptera, Scarabaeoidea, Melolonthinae) with description of 10 new species, Revue suisse de Zoologie 127 (1), pp. 157-181 : 159-160

Genus Cyphochilus Waterhouse, 1867

Synthetic history of the genus: Waterhouse (1867: description of the genus and of 5 species); Sharp (1876: description of 3 species); Nonfried (1893: description of one species); Fairmaire (1902: description of 2 species); Brenske (1903: description of 8 species); Dalla Torre (1912: catalogue of 26 species); Moser (1915: description of one species and syn. ventritectus Brenske, 1903 = ochraceosquamosus ); Arrow (1938: description of one species); Medvedev [1951: designation of the type species = C. candidus ( Olivier, 1789) ]; Frey (1971: description of one species); Sabatinelli & Pontuale (1998: description of Dedalopterus with redefinition of Malaisius Arrow, 1941 and Cyphochilus ); Li & Yang (1999: revision of Malaisius and notes on Cyphochilus ); Krajčik (2012: catalogue of 32 species); Bezdek (2016: catalogue 12 Palaearctic species).

Type species: Melolontha candida Olivier, 1789 by subsequent designation ( Medvedev, 1951: 231).

Etymology: The name is derived from the Greek words χιϕο=divided, χειλο = labrum.

Diagnosis: The following combination of characters distinguishes Cyphochilus from the other related genera of Melolonthinae : elytra with scales uniformly distributed; apical segment of maxillary palps narrow and long, without any callus or excavation on its outer surface; labrum strongly asymmetric; lateral margin of prothorax regularly curved; claws long and with large base; parameres strongly asymmetric.

Description: The genus Cyphochilus is defined by the following characters: body with integument brown to entirely black; upper surface of body covered with scales not forming white spots nor stripes; pygidium and abdomen without metallic reflex; antenna 10-segmented; antennal club in males and females 3-segmented; antennal club in males large, generally longer than footstalk ( Fig. 21 ) more rarely as long as footstalk, or even shorter ( Fig. 22 ); footstalk in males with third and fourth segments subequal; claws large at base, not cleft at apex with basal tooth beneath, lower margin simple; outer and inner teeth subequal; dorsal margin of claws uniformly curved; apical segment of maxillary palp narrow not excavated; labrum not transverse, deeply sinuate, strongly asymmetric; mentum transverse, with Y-shaped carina; clypeus semi-circular, not very large, laterally continuous with canthus, flat or concave and separated from front by suture; front flat, with lateral margin near eyes not elevated; eyes not prominent; vertex concave; prothorax transverse with lateral margin regularly curved, simple, not serrated, without erect setae, anterior and posterior margin not margined, posterior margin without erect setae; elytra with four elevated costae in addition to sutural one ( Fig. 20 ) or completely without costae ( Fig. 19 ); pygidium rounded or triangular, in males without any tubercle; mesosternum not produced ( Fig. 16 ) or produced between mesocoxae ( Figs 17-18 ); metasternum with long hairs, shining; metepisternum narrow, more than three times as long as its breadth with metepimera small; abdominal sternites with scales, laterally without white spots; abdominal sternites connate with sutures absent in middle; sixth abdominal sternite not retracting under the fifth sternite; last spiracle located on suture between fifth visible abdominal sternite and propygidium; anterior coxae transverse, not prominent; mesofemur in males not enlarged; not projecting out laterally from body very much; anterior tibiae in males 1-3-toothed, in females 3-toothed; in males and females with spurs, located in front of hollow between basal and median tooth; external margin of protibiae not transparent; hind and middle tibiae in both sexes without complete transverse carina (a tubercle is present externally); dorsal margin of hind tibiae without teeth or spines; tarsomeres thick and short, sparsely pilose beneath; first segment of hind tarsi subequal or shorter than second; wings and humeral callus developed in males and females; posterior coxae not close to the median coxae in both sexes; parameres fused basally, generally strongly asymmetric bilobate or simple; endophallus membranous.

Remarks: The genera closest to Cyphochilus are Malaisius Arrow, 1941 and Dedalopterus Sabatinelli & Pontuale, 1998 , from which it is distinguishable by the characters already indicated in the diagnosis.

Due to the 3-segmented antennal club, that differentiates Cyphochilus from all other Melolonthinae , this genus has been included in the tribes Rhizotrogini ( Medvedev, 1951) or Leucopholini ( Bezdek, 2016) , with a prevalence for the latter. Matsumoto (2010) has rightly questioned the validity of the tribe Leucopholini as natural group. In a recent molecular phylogenetical analysis ( Eberle et al., 2019), two genera of Leucopholini , namely Dedalopterus and Psilopholis Brenske, 1892 , tested with other few genera of Melolonthini, showed affinities to two different lineages. However, the phylogenetic relationships of Melolonthinae are far from being fully understood and therefore I prefer to treat, for the time being, Cyphochilus at the level of the subfamily Melolonthinae incerta sedis. The different species of the genus Cyphochilus stand out among the Melolonthinae for the extraordinary parameres that evolved, like in the Sericini, in diverse forms and thus making it easy to differentiate the species. Both the shape of the aedeagus and the external morphology allow a certain grouping of the species, at least for some of them. Waterhouse (1867) recognized that it was possible to distinguish species having a “mesosternum armed with a spur” which he grouped in Sect. 1 and species having a “mesosternum unarmed” which he grouped in Section 2. This work examines the species of the Section 1, in which the species have also as another shared trait, the elytra are smooth and lack elevated striae.

Formal names are not proposed for these “Sections”, as their purpose is to facilitate treating and identifying the species. They are not intended to represent phylogenetic clades.

Section 1a

Species with mesosternum armed with a long spur: length in lateral view 1-2 mm ( Fig. 18 ).

Figures

Figs 15-22. General morphology of Cyphochilus. (15) Labrum, in frontal view of Cyphochilus farinosus Waterhouse, 1867. (16) Mesosternum, in ventral view of C. farinosus. (17) C. proximus Sharp, 1867. (18) C. candidus (Olivier, 1789). (19) Lateral side of right elytra of C. septentrionalis Waterhouse, 1867. (20) C. farinosus. (21) Antennal club ♂ of C. hmong n. sp. (22) C. septentrionalis ♂.