Dasyrhadus Fall, 1910

Gimmel, Matthew L. & Mayor, Adriean J., 2022, Synonymic and Nomenclatural Notes in the Mauroniscidae and Rhadalidae (Coleoptera: Cleroidea), The Coleopterists Bulletin 76 (3), pp. 419-422 : 419-420

Dasyrhadus Fall, 1910

The peculiar genus Dasyrhadus was until recently classified within Rhadalidae or the melyrid/dasytid subfamily Rhadalinae ( Crowson 1964; Majer 1995; Mayor 2002), although this placement was rejected by Peacock (1987). It was recently and tentatively transferred from Rhadalidae to Mauroniscidae based on a molecular phylogenetic analysis by Gimmel et al. (2019). Dasyrhadus was originally described with two species, but a type species was never designated. This is rectified below.

Fall distinguished his two species, Dasyrhadus impressicollis Fall, 1910 and Dasyrhadus longior Fall, 1910 , based on subtle differences in the width of pronotum, length of elytra, and degree of truncation of female ventrite 5. Based on examination of specimen series from across the range of the genus, we observed a subtle range of variation in the length/width ratios of the pronotum and elytra, shape of ventrite 5, and development of the female hind wings.

The females of Dasyrhadus are stouter than males, differing notably in the proportions of the elytra (single elytron ~3.1 times longer than wide in females, ~3.9 times longer than wide in males), and have poorly developed flight wings, ranging from about half the elytral length to just exceeding the elytral length in specimens examined.Adults of this genus also possess sexual dimorphism in eye size (as Rhadalus LeConte ; see below). Also, abdominal ventrite 5 is broadly, shallowly emarginate in males while it is truncate to slightly sinuate in females; ventrite 6 is exposed in both sexes, with a V-shaped emargination in males and gently arcuate in females. Antennae are also quite different between the sexes, with antennomeres 5–10 distinctly longer than wide in the male and nearly as wide as long in the female.

After examination of the types and original descriptions in light of freshly collected material, we propose the following subjective synonymy:

Dasyrhadus Fall 1910: 144 . Type species: Dasyrhadus impressicollis Fall, 1910 , here designated.

Dasyrhadus impressicollis Fall 1910: 144 .

Dasyrhadus longior Fall 1910: 145 . New junior synonym.

Type Specimens. Dasyrhadus impressicollis , four syntypes, 1 male, 3 females labeled as follows, all deposited in the Museum of Comparative Zoology, Harvard: syntype male [mounted on point, damaged, see Remarks], “Brtltt [Bartlett] Spgs/Cal/r. A. Fenyes [white printed label]//H. C. FALL /COLLECTION [white printed label]//MCZ-ENT/00732186 [printed barcode]”; syntype female [mounted on point, right metatibia and tarsus missing], “Brtltt [Bartlett] Spgs/Cal/r. A. Fenyes [white printed label]] //H. C. FALL /COLLECTION [white printed label]// Dasyrhadus /impressicollis/Fall [red-rimmed handwritten label]//MCZ-ENT/00732184 [printed barcode]”; syntype female [mounted on point, antennomeres 3–11 of right antenna and tarsus of left middle leg missing], “Brtltt [Bartlett] Spgs/Cal/r. A. Fenyes [white printed label]//H. C. FALL /COLLECTION [white printed label]//MCZ-ENT/00732185 [printed barcode]”; syntype female [mounted on card; missing antennomeres 10 and 11 from right antenna, tarsus from left middle leg, and right hind leg; abdomen and genitalia mounted on second card], “Brtltt [Bartlett] Spgs./Cal/r. A. Fenyes [white printed label]] //H. C. FALL / COLLECTION [white printed label]//impressi-/ collis/ TYPE [white printed and handwritten label]//M. C. Z./Type 24274 [red printed and handwritten label]// Jan. – Jul. 2006 /MCZ-Image/ Database [black-rimmed white printed label]// MCZ-ENT/000224274 [printed barcode]// Dimetylhydantoin-/formaldehyd/Water soluble [white printed label]”. Each of the four syntypes have had the following label attached: “ SYNTYPE / Dasyrhadus / impressicollis Fall, 1910 /det. Gimmel & Mayor 2022 [red printed label]”. Fall (1910) originally described this species from three localities: Bartlett Springs, Lake Co., California; Big Trees, Calaveras Co., California; and Tenino, Thurston Co., Washington. However, he wrote “type” next to the Bartlett Springs locality, thus restricting the syntype series. We deem lectotypification unnecessary in this case.

Dasyrhadus longior , three syntypes, 1 male, 2 females labeled as follows, all deposited in the Museum of Comparative Zoology , Harvard: syntype male [mounted on point], “Fieldbrook/26.5.03/Cal [white printed and hand written label]//H S Barber/ Collector [white printed label]//H. C. FALL / COLLECTION [white printed label]// Dasyrhadus / longior/Fall [red-rimmed handwritten label]//MCZ-ENT/00732193 [printed barcode]”; syntype female [mounted on point], “Fieldbrook/26.5.03/Cal [white printed and handwritten label]//H S Barber/Collector [white printed label]//H. C. FALL /COLLECTION [white printed label]//MCZ-ENT/00732194 [printed barcode]”; syntype female [mounted on card; missing antennomeres 8–11 from right antenna, and tarsus from right foreleg; abdomen and genitalia mounted on second card], “Fieldbrook/26.5.03/Cal [white printed and handwritten label]//H S Barber/ Collector [white printed label]//H. C. FALL / COLLECTION [white printed label]//longior/ TYPE [white printed and handwritten label]//M. C. Z./Type 24275 [red printed and handwritten label]// Jan. – Jul. 2006 /MCZ-Image/Database [white printed label]// MCZ-ENT/000224275 [printed barcode]// Dimetylhydantoin-/formaldehyd/Water soluble [white printed label]”. Each of the three syntypes have had the following label attached: “ SYNTYPE / Dasyrhadus / longior Fall, 1910 /det. Gimmel & Mayor 2022 [red printed label]” .

Remarks. The male syntype of D. impressicollis is damaged as follows: head and pronotum detached from body, and both are glued upside down on the point. Left maxillary palpus, antennomeres 6–11 of right antenna, antennomeres 3–11 of left antenna, right foreleg, left middle leg, and tarsus of right hind leg are missing.

As a consequence of the above synonymy, only a single species of Dasyrhadus is recognized, and we select D. impressicollis as the valid name. We have seen specimens from California, Idaho, Oregon, Utah, and Washington; the species has also been reported from British Columbia, Canada ( Hatch 1962: 87).