The Jewel of Rain Beetles:Pleocoma staff Schaufuss, 1870

I am indebted to Brady Richards for permission to post his fine photo that originally appeared at BugGuide.com.

2. Notes on Dinacoma Casey, 1889:Will the real marginata please stand up?

Continued from Part 1. ...

With the Type of D. marginata at hand, including a rare exemplar from Blaisdell's belated designated type locality, Ocean Beach, I examined, borrowed, or collected as many Dinacoma as possible. Specifically, those specimens or populations that were morphologically similar to D. marginata - or, what I henceforth refer to as the "marginata species group."

From studying Dinacoma ecology and bionomics, I was fortunate to rediscover George's Baja population, the impetus for this project, that he had collected in the late 1960s, at two separate alluvial drainages.

Dinacoma sp. near marginata
Baja California, Mexico
Male ~ Female
The Pleistocene coalesced alluvial fans and valleys along the Pacific slope of the San Jacinto Mountains, in Riverside County, were surveyed and sampled.

Bautista Canyon, San Jacinto Mountains
Representatives of the extant San Diego County coastal populations - Del Mar, Torrey Pines, Encinitas - were collected, as well as the desert transition Scissor's Crossing deme.

Dinacoma marginata (Casey, 1886)
Left to Right: Del Mar, Torrey Pines, Encinitas
San Diego Co., California
Males
Dinacoma sp. near marginata
San Felipe Valley/Scissors Crossing
San Diego Co., California
Male ~ Female
I was able to locate one specimen collected in the 1970s from Eaton Canyon, in the San Gabriel Mountains, representing the Los Angeles County demes. Despite a search of the Alan Hardy collection, housed at the California Academy of Sciences, San Francisco, I didn't find any Dinacoma reflecting his Glendale, Los Angeles County, record (Hardy 1974) nor in the Academy collection. On my behalf, renowned coleopterist and long time friend, Richard Cunningham, of Chino, CA, acquired a very interesting specimen from the upper Mojave Desert, north of the Little San Bernardino Mountains, in Riverside County (below, left).

The discovery of this population threw the proverbial monkey wrench into my distributional hypothesis for the genus. My prior speculation was that the transverse ranges of the San Gabriel and San Bernardino Mountains, and the peninsular ranges of the San Jacinto, Santa Rosa, and Laguna Mountains, and the Sierra Juárez and Sierra San Pedro Mártir were sufficiently formidable to confine the paleo expansion of the marginata species group to lower southern California south to the Baja peninsula. The Mojave Desert specimen placed the genus outside of my presumed distributional boundaries.(D. caseyi 's distribution into the Colorado Desert was plausible by Pleistocene - probably much earlier - access through the San Gorgonio Pass).

Field surveys for new marginata demes were based on their ecological association with sandy alluvial soils occurring in, or contiguous with, subcoastal scrub, chaparral, desert transition, and desert washes. Interestingly, observations indicate other genera of closely related Melolonthini occupy similar alluvial habitats. Amblonoxia carpenteri (LeConte) was extremely common (apparently displacing Dinacoma ???) at Temecula Creek, Aguanga, Riverside County, the upper Santa Ana River wash, San Bernardino County, and the Santa Clara River floodplain, in Los Angeles County. These localities appeared perfect for supporting Dinacoma. Soil composition. Floral community. However, I am at a loss to explain their absence. Competitive exclusion? Moreover, there is a conspicuous break in distribution between the San Jacino Mountains' populations and the historic localities of the lower San Gabriel Mountains. It would seem that there should be populations, yet undiscovered, along the cismontane canyons of the western San Bernardino Mountains (e.g., Mill Creek, Banning Canyon, Mission Creek) then possibly eastward toward San Gorgonio Pass.

One element that was crucial to my review was the addition of the unknown female of D. caseyi as well as those of all known extant marginata demes. Other than a brief note (Hardy 1977:92) regarding a damaged female of D. caseyi - inadvertently cited as D. marginata (this error has never been formally corrected) - females had remained undescribed. As a result, prior taxonomic diagnoses of Dinacoma species had relied exclusively upon a composite of male morphological characters. Based on recent studies of other conterminous genera of Melolonthini (Phyllophaga Harris, Woodruff 2004; Polyphylla Harris, La Rue 1998, and in preparation), I suspected females would also have characters that are supplemental to interspecific diagnostic criteria.

End of Part 2.

Literature Cited and Internet Resources
Casey, T.L. 1889. Coleopterological Notices. I. Annals of the New York Academy of Sciences 5:36-198.

Hardy, A.R. 1974. Revisions of Thyce LeConte and related genera (Coleoptera:Scarabaeidae). Entomology. State of California Department of Food and Agriculture. Occasional Papers #20. 47 pages.

Hardy, A.R. 1977. Observations on some rare Scarabaeidae mainly from California. The Coleopterists' Bulletin 31(1): 91-92.

La Rue, D.A. 1998. Notes on Polyphylla Harris with a description of a new species. (Coleoptera:Scarabaeidae:Melolonthinae). Insecta Mundi 12(1/2):23-37

Woodruff, R.E. 2004. Revision of the Phyllophaga of Hispaniola (Scarabaeidae: Melolonthinae). Insecta Mundi 18(1-4):1-154.

Bautista Canyon image courtesy of Eastern Federal Lands Highway Division. Colorado Desert Wash image courtesy of www.tarleton.edu

© Delbert La Rue 2010. All Rights Reserved.

Africa's Terrible Hairy Fly: Rediscovered

Scientists have rediscovered a bizarre flightless species of fly, Mormotomyia hirsuta. The 1 cm-long insect had been collected only twice before in 1933 and 1948. It's only known habitat is a bat-filled cleft on an isolated rock formation in Kenya's Ukazi Hills where it breeds in bat feces.

More photos and reading from the BBC News Science article may be found here.

Notes on Dinacoma Casey, 1889:Will the real marginata please stand up?

My taxonomic review of the genus Dinacoma began several years ago when my good friend and colleague, the eminent coleopterist and Buprestid guru, George Walters, La Puente, CA, knowing of my affinity for New World Melolonthines, asked what my opinion was of two male specimens of Dinacoma in his cabinet from the Mexican state of Baja California. Previously, the genus had been considered restricted to southern California: Los Angeles, Riverside, and San Diego Counties. I soon realized the locality of George's specimens extended the known distribution of the genus about 200 kilometers south as well as representing a new country record - all of which piqued my curiosity and scarabaeoid interests. I had no way of knowing how little of the Dinacoma puzzle lay before me nor the convolution of the scientific quest I was about to undertake:


Why a review and not a revision - and what's the difference? A revision usually involves nomenclatural changes which isn't the case in Dinacoma - as presently understood (more about that later). What is required is a modern redescription of the species D. marginata (Casey) which, I believe, has been taxonomically obscured by a variety of authors. This would establish a taxonomic and morphological foundation on which to evaluate the various populations - some of which represent discrete undescribed taxa.

The Neartic Melolonthine genus Dinacoma was proposed by Thomas L. Casey (below) to taxonomically situate Thyce marginata Casey, which he later felt was morphologically intermediate, between Thyce LeConte and Polyphylla Harris. Regarding his action, Casey stated (1889:174) "... The characters agreeing with Thyce, reside in the structure of the palpi and tarsal claws, and those that ally it most directly with Polyphylla, are in the greatly developed antennal club, and the short tarsi." In his characterization of the genus, Casey emphasized the differences in the configuration and number of antennal lamella, unequally bifid metatarsal claws, composition of dorsal vestiture, apical two antennomeres anteriorly expanded, profile of the maxillary palpomeres, connate abdomeres, and geographic distribution.

For several decades the known distribution of the genus, that has included two species, D. marginata and D. caseyi Blaisdell (1930), has been adversely impacted and fragmented because of unprecedented habitat destruction and cumulative modification for recreational, residential and urban development. Undoubtedly, all of the former Los Angeles County populations (e.g., Glendale, Pasadena, Eaton Canyon) have probably been extirpated as no recent specimens from those localities are known. Additionally, D. caseyi is precariously in danger of extinction because of extremely limited range and imminent ecological degradation to a few extant populations.

Based on the dorsal morphology, it was apparent that George's specimens were related to, if not conspecific with, D. marginata. However, there were slight differences from the known populations in California but, with only two male specimens from a previously unknown population, any further diagnosis, I felt, would be speculative at best. From my concurrent studies of Polyphylla, I was aware that the addition of the female morphology and genitalia could very well offer further diagnostic characters.

In addition to Casey's original description (1889), I began with a perusal of prior treatments of Dinacoma: Blaisdell (1930), and Hardy (1974). Both authors had slightly different interpretations of D. marginata, I suspect, because of the disparity of specimens they had before them and the age of their publications. Moreover, neither author studied Casey's type. Similarly, Evans and Hogue (2006) stated that the genus "lacks distinct stripes [vittae] on the elytra." Unfortunately, their assertion isn't exactly accurate nor supported by the dorsal vestiture of either species of Dinacoma. As a result of these different interpretations, inevitable confusion arose with the assessment of George's Baja specimens, the discovery of a disjunct population from the upper Mojave Desert, and the apparent morphological divergence of populations from the Pacific slope of the San Jacinto Mountains, Riverside County. To proceed further, it became obvious that the taxonomic definition of D. marginata required closer scrutiny as well as clarification.

"A journey of a thousand miles begins with a single step."
Lao-tzu, Chinese philosopher
In order to construct a taxonomic foundation upon which to evaluate the various marginata demes, common sense suggested starting at the beginning, as the proverbial single step: a morphological review of the Type of D. marginata, pictured here:




Three labels with the following text accompany the Type:

1) "Dinacoma marginata Csy." handwritten in black ink;
2)"CASEY bequest 1925" block printed in black ink;
3) "TYPE USNM 35885" red label: "TYPE USNM" block printed, "35885" handwritten, all in black ink.

I was surprised to find that no locality label was present.

Casey did not specify a type locality for D. marginata other than the reference to "California, San Diego County" that was associated with the former Thyce marginata. This was common practice as early authors and collectors were less precise about such methodologies and geographic locations were not as well defined as today. In his subsequent treatment, Blaisdell (1930) inexplicably redesignated the type locality to "Ocean Beach, San Diego County, California," forty years after Casey's original description. Unfortunately, he did not explain the reasoning behind his action nor offer why he specifically chose that particular locality. I can only conclude the obvious in that his effort was to specify a less ambiguous type locality. It is unknown whether Casey's type and Blaisdell's Ocean Beach specimens were from the same area/locality. This population is presumed extirpated. The most recent specimen that I was able to locate was collected in the late 1930s:



Specimen courtesy of Ron McPeak, Battle Ground, WA.

While Blaisdell's locality implies a littoral association, all known extant coastal populations of D. marginata are ecologically associated with subcoastal scrub/chaparral occurring in sandy alluvial soil.
End of Part 1.

Literature Cited and Internet Resources
Blaisdell, F. E. 1930. Revision of the genus and species of Dinacoma with description of a new species (Coleoptera: Scarabaeidae). Pan-Pacific Entomologist 6(4):171-177.

Casey, T.L. 1889. Coleopterological notices I. Annals of the New York Academy of Sciences 4:39-198.

Evans, A.V., and J.R. Hogue. 2006. Field Guide to Beetles of California. (California Natural History Guides) University of California Press. 362 pages.

Hardy, A.R. 1974. Revisions of Thyce LeConte and related genera (Coleoptera: Scarabaeidae). Occasional Papers (Entomology, State of California) 20: 47 pp.

T.L. Casey image courtesy of Louisiana State Arthropod Museum where a complete list of Casey publications, some available in .pdf format, is available.

© Delbert La Rue 2010. All Rights Reserved.

Rosalia alpina (Linnaeus, 1758)

Rosalia alpina (Linnaeus, 1758)
Family: Cerambycidae
Subfamily: Cerambycinae
Tribe: Rosalini. Distribution: Europe - extirpated in parts, listed as endangered or protected in others.

Original illustration approximately 6X8-inches. Winsor & Newton watercolors and Faber-Castell Polychromos colored pencils in an A3 watercolor Moleskine Folio.


This is part of a watercolor illustration that I posted here.