Megistophylla Burmeister, 1855

Li, Chun-Lin, Yang, Ping-Shih & Wang, Chuan-Chan, 2016, Two new species of Megistophylla Burmeister (Coleoptera: Scarabaeidae: Melolonthinae) from Taiwan, with notes on the genus, Zootaxa 4126 (2), pp. 240-250 : 241-242

Genus Megistophylla Burmeister, 1855

Megistophylla Burmeister, 1855: 424 . Type species: Megistophylla junghuhni Burmeister, 1855 by monotypy. Hecatomnus Fairmaire, 1891 : CCII. Type species: Hecatomnus grandicornis Fairmaire, 1891 by monotypy.

Description of male. Body length 14.8–26.4 mm. Body oval-elongate; blackish brown to castaneous; moderately shiny. Dorsal surface densely and evenly punctate, punctures deep and rugopunctate; dorsum setiferous, majority of setae tiny, far smaller than diameter of puncture (high magnification for observation necessarily required), without or with a few long setae at anterior margin and base of pronotum, and base of elytra. Lateral margins of pronotum and elytra with fringe of long, robust setae. Antennae with 10 antennomeres, antennal club composed of 5, 6, 7, or 8 antennomeres by species, club straight to strongly outwardly curved, length of club slightly longer to maximum 8 times longer than basal antennomeres; basal antennomere prior to first club antennomere usually sharply enlarged. Clypeus transversally narrow; frons flat, base of frons transversally carinate. Pronotum usually with lateral margin smooth or weakly serrate at anterior or basal half; declivities at side usually with gibbosity behind middle of pronotum. Scutellum punctate or almost impunctate. Elytral sutural costa well developed, widened apically, discal costae entirely disappeared or with 3 weakly developed costae between sutural costa and humerus. Pygidium convex centrally. Protarsi, mesotarsi, and metatarsi with short, robust setae along ventral side of tarsomeres 1-5; protarsi and mesotarsi without or with setae in different length sparsely moderately to densely aggregated at apex of tarsomeres 1–4 or 1–3; length of metatarsi subequal to or longer than metatibia. Parameres of male genitalia symmetrical, usually goose-head-like with a strongly to moderately concave, wrinkled area at middle when viewed laterally (see Figs. 9 & 11 ), parameres divided into upper and lower parts in a few species, lower parts varied in length and in shape among species. Female. Antennal club composed of 7 antennomeres (in M. junghuhni and M. andrewesi ), shorter than basal antennomeres and rounded in shape; apex of clypeus more emarginate at middle than in male; length of metatarsi shorter than metatibia; metatibia and metafemora more stout than in male.

Diagnosis. Species of Megistophylla are characterized by the transverse carina on frons and overall dorsal punctation that are both distinct characters also commonly shared by the following east Asian rhizotrogine genera: Holomelia Brenske, 1891 , Pentelia Brenske, 1891 , and Miridiba Reitter, 1902 . The male Megistophylla can be separated from those close genera by the following combination of characters: length of antennal club subequal to or distinctly longer than basal antennomeres (antennal club distinctly shorter than basal antennomeres in Holomelia , Pentelia , and Miridiba ); frons narrowly developed (transversally widened in Holomelia , Pentelia , and Miridiba ); lateral margins of pronotum smooth or weakly serrate at basal half (completely serrate in Holomelia and Pentelia and most species of Miridiba ); protarsi and mesotarsi without or with setae in different length sparsely/ densely aggregated at apex of tarsomeres 1–4 or 1–3 (having a tuft of tiny, dense setae in same length on apex of ventral tarsomeres 1–4 in Holomelia , Pentelia , and Miridiba ); parameres of genitalia usually goose-head-like in shape with a strongly to moderately concave, wrinkled area at middle when viewed laterally (lacking concave area at middle of parameres in Holomelia , Pentelia , and Miridiba ).

Distribution. Central to southwestern China, Indochina, Malay Peninsula, Sumatra, Java, India (Assam), Taiwan.

Remarks. Arrow (1938) noted that all of records of Megistophylla were male except for the female syntype of M. junghuhni . This phenomenon is rather unusual in rhizotrogine scarab beetles, even though an effective collecting method (FIT) can yield numerous male specimens (see below in M. formosana and M. xitoui ) in the field. During the course of investigation, we only located two female Megistophylla specimens ( M. junghuhni and M. andrewesi , respectively) for observation and comparison. Unlike other rhizotrogine scarabs with agricultural importance, the natural history of Megistophylla is barely known. Based on information from various specimens, particularly those of the two new species collected and described below, the adults of Megistophylla species are likely crepuscular/nocturnal, are not generally attracted to lights, and do not feed.

Figures

FIGURES 9 – 12. Parameres of Megistophylla. (9, 11, lateral view; 10, 12, dorsal view). 9 – 10. Megistophylla formosana new species; 11 – 12. Megistophylla xitoui new species. Scale bar = 1.0 mm.