The Diphyllostomatidae includes three species in the genus Diphyllostoma.
The group is endemic to the west coast of California in the United States. The
natural history of the group is poorly known, and larvae have not been described.
Length 5.0-9.0 mm. Shape elongate-oval. Color brown to reddish-brown, without
metallic reflections. Head prognathus, not deflexed. Antennae straight (not
geniculate), 10-segmented with 3-segmented, unopposable club (all segments tomentose).
Eyes with acone ommatidia, lacking canthus. Clypeus lacking tubercle or horn.
Labrum concealed beneath clypeus. Mandibles prominent, quadrate or rounded at
apex, produced beyond apex of labrum. Maxillae with 4-segmented palpi; labium
with 4-segmented palpi. Pronotum weakly convex, base narrower than elytral base,
lacking tubercles, ridges, horns, or sulci. Elytra elongate, weakly convex,
with weakly impressed, punctate striae. Pygidium concealed by elytra. Scutellum
exposed, parabolic. Legs with protrochantin exposed, procoxae subconical, mesocoxae
virtually contiguous; protibiae serrate on outer margin, apex lacking articulated
spur; meso- and metatibia with ridges, apices with 2 spurs; spurs mesad, adjacent
(not separated by basal metatarsal segment); tarsi 5-5-5; claws equal in size,
simple; empodium present, extending to apex of fifth tarsal segment, with 2
setae. Abdomen with 7 visible sternites; 7 functional abdominal spiracles situated
in pleural membrane. Wings well developed in male (vestigial in female), M-Cu
loop and one apical detached vein present. Male genitalia trilobed. References:
Holloway 1972; Scholtz 1990.
The genus Diphyllostoma was originally placed in the family Lucanidae
by Fall (1901) based on the 10-segmented antenna and lack of an eye canthus
(typical characteristics of the family Lucanidae). However, several significant
characters of Diphyllostoma are not found in other members of the family
Lucanidae or other scarabaeoids. These include abdomen with 7 ventrites, exposed
second abdominal segment, exposed protrochantin, and protibial spur lacking.
Holloway (1972) proposed the family Diphllyostomatidae for the genus Diphyllostoma
because of these unique characters.
Based on comparative studies, Holloway (1972) suggested the Diphyllostomatidae
may be most closely related to the family Geotrupidae. Browne (1993), Scholtz
(1990), and Browne and Scholtz (1995) hypothesized that the Diphyllostomatidae
is the sister group to the Lucanidae. Diphyllostomatid and lucanids comprise
the sister group to a clade that includes the families Glaphyridae, Trogidae,
Pleocomidae, and Bolboceratidae.
The genus Diphyllostoma includes three species that are found only
in California in the western United States (Fall 1901, 1932).
New World Genus of Diphyllostomatidae
Females differ from males in having greatly reduced eyes and vestigial wings.
Life history information is scant. The adults are diurnal.
Immatures are not known but are probably of the scarabaeoid form and probably
live in the soil.
BROWNE, D. J. 1993. Phylogenetic significance of the hind wing
basal articulation of the Scarabaeoidea (Coleoptera). Ph.D. Thesis, University
of Pretoria, Pretoria, South Africa.
BROWNE, D. J. and C. H. SCHOLTZ. 1995. Phylogeny of the families
of the Scarabaeiodea (Coleoptera) based on characters of the hindwing articulation,
hindwing base and wing venation. Systematic Entomology 21: 145-173.
FALL, H. C. 1901. Two new species of Lucanidae from California.
Canadian Entomologist 33: 289-292.
FALL, H. C. 1932. Diphyllostoma: a third species.
Pan-Pacific Entomologist 8: 159-161.
HOLLOWAY, B. A. 1972. The systematic position of the genus
Diphyllostoma Fall (Coleoptera: Scarabaeoidea). New Zealand Journal
of Science 15: 31-38.
SCHOLTZ, C. H. 1990. Phylogenetic trends in the Scarabaeoidea
(Coleoptera). Journal of Natural History 24: 1027-1066.