At the time of getting familiar with the genus...

In the summer of 2008 I had the opportunity of visiting Dr. Charles O'Brien's Collection (CWOB), looking for identified Lachnopus specimens in order to include them in my analysis. Part of CWOB's specimens had been compared with types in European collections. In only 10 days of careful observation I learned a lot about the group.

I'm going to illustrate some of my observations with images of morphotypes of L. curvipes (Fabricius, 1787) which I presented at the ESA meeting in 2011. You can access the whole presentation here.

- There is sexual dimorphism: the usual, males are slender and sometimes smaller than females; something quite 'particular', the males have a slightly longer or slender rostrum than the females, which is the opposite of what can be observed in the Curculionidae in general.

- The posterior tibiae are also dimorphic in several species. Usually the male posterior tibiae are hairy in comparison with those of the females.

In this species the dimorphism can be considered extreme, judging by the presence of a very developed tooth in the male tibia, but if you see only the amount of hairs, you get the idea.

Beyond these characteristics which apply to several species, I've found a couple of identification conflicts among CWOB identified specimens:
 - (L. atramentarius vs. L. inconditus), (L. planifrons vs. L. mundus) result very similar, there was at least one specimen of each compared with the type but, for one species it was a male compared and for the other it was a female.
- The group formed for (L. coffeae, L. seini and L. yaucona) is not easy to separate... there are seven species recorded from Puerto Rico: L. coffeae (along with the variety L. coffeae montanus), L. curvipes, L. kofresi (from Mona Island), L. seini, L. trilineatus, L. valgus and L. yaucona. Until now I can only recognize L. kofresi which is quite distinct from all other Lachnopus known to me, L. curvipes, which is the most widespread and variable species and the remaining, except for the montanus variety of L. coffeae, might possibly be variations of the same species.

There are also some specimens from Cayman Islands, Cuba and Jamaica that are probably undescribed.

The most important conclusion of this 'get to know Lachnopus' phase was that the variation within the genus is quite extreme, over all on the head appearance (including the shape of the rostrum, the projection of the eyes and the width of the frons), colorations and scale distribution patterns. In some cases there is also intraspecific variation.

At this time and after my experience with Apodrosus I knew that the phylogenetic analysis was not going to be easy!

Diversity

Lachnopus is currently placed in the tribe Geonemini Gistel, according to Alonso-Zarazaga & Lyal, 1999). With 66 described species and several additional species waiting to be described, it constitutes the most diverse and widespread genus of Caribbean borad-nosed weevils.
Until now Lachnopus ranges from the south-eastern United States to Saint Vincent in the Lesser Antilles, with the highest species diversity concentrated in the Greater Antilles; most of Lachnopus species are apparently narrowly distributed and exhibit high rates of inter and/or intra-island endemism (see O’Brien and Wibmer 1982).
The species currently placed in the genus are extremely variable:

• Size ranging from 5 to 25 mm
• Body shapes ranging from elongate to oval
• Integument and scale color
• Wide spectrum of scale distribution patterns

According to van Emden’s Key (1944) Lachnopus can be recognized by a rostrum weakly and evenly convex throughout; antennal scape extending to, or slightly passing beyond middle of eye; frons between eyes conspicuously narrower than dorsal surface of rostrum; head not constricted posteriad of eyes; eyes only moderately convex; humeri only slightly wider than posterior margin of pronotum; femora unarmed; tibiae ventrally denticulate; and metatibial corbel (bevel sensu Thompson 1992) lacking scales. BUT, based only on the frons width, you can tell that not all species fit in van Emden's definition.

From left to right: top row: L. valgus, L. aurifer, L. planifrons and L. histrio; bottom row: L. albomaculatus, L. campechianus and L. acuticollis.

With so much variation within the same genus, it seems to me that Lachnopus has been the "trash-can" of Caribbean entimines for a long time. In fact, Woodruff (1985: 371) used one of my favorite phrases in weevil's literature to describe Caribbean diversity: 'a ‘Pandora’s Box of taxonomic confusion'.
The same happens for the whole tribe (I will tell you later why).

References
     Alonso-Zarazaga, M. A., and Lyal, C. H. C. (1999). ‘A World Catalogue of Families and Genera of Curculionoidea (Insecta: Coleoptera) (Excepting Scolytidae and Platypodidae).’ (Entomopraxis: Barcelona, Spain.)
     O’Brien, C. W., and Wibmer, G. J. (1982). Annotated checklist of the weevils (Curculionidae sensu lato) of North America, Central America, and the West Indies (Coleoptera: Curculionoidea). Memoirs of the American Entomological Institute 34, 1–382.
     van Emden, F. (1944). A key to genera of Brachyderinae of the World. Annals & Magazine of Natural History 11(XI), 503–532, 559–586.
     Thompson, R. T. (1992). Observations on the morphology and classification of weevils (Coleoptera, Curculionoidea) with a key to major groups. Journal of Natural History 26, 835–891.
     Woodruff, R. E. (1985). Citrus weevils in Florida and the West Indies: preliminary report on systematics, biology and distribution (Coleoptera: Curculionidae). The Florida Entomologist 68, 370–379.

On the beginning

This project started in the fall of 2007 when I began as a M.Sc. student at the University of Puerto Rico in Mayaguez (UPRM). I came here with a deep infatuation about entimine weevils, knowing that they are very diverse and that its taxonomy is very chaotic.
During my first months I became familiar with the Puerto Rican entimine fauna and learned a lot about morphology and bibliographic resources to which I didn't had access before.
As part of my duties as Research Assistant at UPRM, I had the opportunity to travel to the Dominican Republic during 20 days in the summer of 2008, intensely collecting insects, particularly weevils and more importantly entimines. We got a lot of specimens during that trip!
At that time my thesis was planned to include systematic studies in the genera Apodrosus and Lachnopus. I focused first in Apodrosus, describing 11 new species and performing a phylogenetic analysis. You can see part of the process at http://apodrosus.blogspot.com/
When it came the time to focus in Lachnopus, with the material collected in the Dominican Republic, I visited the Collection of Dr. Charles O'Brien in Arizona and during those 10 days I discovered several factors that constitutes Lachnopus as an extraordinary challenge from the morphological, taxonomic and systematic points of view.
The aim of this blog is to gather as many data as I can recall about this project, as I'm not sure if I can continue it in the close future. Perhaps I can get someone to take advantage of my history with the group... who knows?... I would like that!
At this point, we (my M.Sc. advisor Dr. Nico Franz and I) have published a phylogenetic assessment for the genus. There is so much 'accessory information' that I could not include in the paper; that is what I plan to collect in this blog. Let's see how much this impulse lasts!