Charnwood Confusion Continues

Folks who have heard me talk about Mastigusa macrophthalma (the "Charnwood Spider") will know that I'm dubious about the identity of this spider, and indeed about the validity of M. macrophthalma as a species. A recent paper takes a close look at Mastigusa from across Europe ... and doesn't solve the problem. The good news is that Mastigusa appears to be a solid genus, dating back 45 million years. I'll let the authors give you the bad news in their own words:

"Morphology-wise, the clade composed by specimens from Southern Spain and the United Kingdom (and the single specimen from the Pyrenees), do not fit with any of the currently described Mastigusa species, showing marked differences with the observed type-material, mostly regarding the morphology of the male palp. Iberian populations have always been considered as M. arietina, while in the United Kingdom both M. arietina and M. macrophthalma have been historically reported, but again only based on eyes characters. The overall morphology and dimensions for these specimens, and their distribution fit with M. arietina, but the male palp consistently shows marked differences with all the other specimens observed. Our molecular data strongly suggests that these specimens could belong to a new, previously overlooked, Mastigusa species."

As a taxonomic lumper I haven't changed my opinion that we're probably dealing with Mastigusa arietina, but something seems to have happened 19 million years ago which shook this genus up. My geology isn't good enough to speculate that that may have been. 

Castellucci, F., Scharff, N., & Luchetti, A. (2023) Molecular systematics and phylogenetics of the spider genus Mastigusa Menge, 1854 (Araneae, Cybaeidae). Molecular Phylogenetics and Evolution, 107833. 

https://www.sciencedirect.com/science/article/pii/S1055790323001331

 

A simple (and cheap) macro diffuser for Olympus TG cameras

Photography - it's all about the lighting (the clue is in the name). 

Olympus TG cameras are great for macro photography. Working at very close range can be difficult, often blocking the light needed to illuminate the subject. The Olympus TG Light Guide is a very helpful (if over-priced) accessory which directs light from the front LED in a circular ring light-fashion onto the subject. This is useful but can be a problem when taking macro photos of shiny subjects. The clear plastic at the front of the TG Light Guide does not provide much in the way of diffusion, causing a bright ring-shaped hot spot on images:

The diffuser consists of a white plastic pudding cup. I bought mine online but you could probably find something which would do the job in the dessert section of the supermarket (note: eat pudding before use).  Turn the cup upside down and place the Light Guide on the top of the cup, draw around the inside of the lens hole in the Light Guide and cut out a hole (you can do it less crudely than I did, but mine still works fine). 

To use, place the subject under the cup, put the camera (with the Light Guide) on top, compose and take your photos. The remaining rim of the cup covers the clear ring of the Light Guide and diffuses the LED further, reducing hot spots on the subject. The cup also acts as a copy stand which reduces camera movement when using the focus stacking functions of the camera. 

It's cheap, it works, and you get to eat pudding. What's not to like?