Prior to 2015, Dicranopalpus ramosus was considered one of the easiest UK harvestmen to identify in the field thanks mainly to the very distinctive appearance of its 'forked' palps, which results from a very elongated apophysis on the palpal patella. When at rest it also characteristically holds its legs straight out from its body in two narrow fans.
But that all changed with the publication of a paper by Wijnhoven & Prieto (2015) in which the authors assert that Dicranopalpus caudatus, previously considered to be a synonym of Dicranopalpus ramosus, is in fact a valid separate species. Furthermore some specimens of supposed Dicranopalpus ramosus collected from the UK were shown, on re-examination, to be Dicranopalpus caudatus.
Wijnhoven & Prieto (2015) do suggest that the two species may be told apart in the field, but more work on microscopically examined material is required to test the robustness of separating these species based on field characters. Therefore identifying the two Dicranopalpus species in the field should, for now, be done with caution.
For both species there is sexual dimorphism with males having a shorter body than the female. The females develop a protuberance at the end of the abdomen - a sort of large bump pointing backwards and more or less obliquely upwards. The tibial apophosis ('fork') on the palps of males is more slender than that of the female. In both sexes, Dicranopalpus ramosus is larger than Dicranopalpus caudatus, but this kind of comparative character isn't that helpful in the field.
Male Dicranopalpus ramosus sometimes have a dark patch across the cephalothorax - crossing the ocularium - which is often described as a Zorro mask! There is relatively rare morph of Dicranopalpus ramosus that has a narrow longitudinal black stripe down the centre of the dorsal side of the body.
Our understanding of the distribution and natural history of Dicranopalpus ramosus is currently clouded due to possible confusion with D. caudatus. The distribution map shown on the Spider and Harvestman Recording Scheme is currently best regarded as a distribution map for Dicranopalpus spp. until the situation is clarified. Wijnhoven & Prieto (2015) have shown that over much of Europe, the ranges of D. caudatus and D. ramosus do not overlap (i.e. they are allopatric) with D. caudatus being largely confined to western, southern and eastern coastal areas of the Iberian Peninsula whilst D. ramosus if found on the northern coastal area of the Iberian Peninsula and over the rest of Northern Europe. However they did confirm a number of comparatively early records of D. caudatus from southern England.
Dicranopalpus spp. was first recorded in the south of England in 1957 and spread rapidly north and westwards to most parts of the UK. Work is required to find out if Dicranopalpus caudatus is still present in the UK and, if so, discover the true distributions of the two species.
Frequently found in shrubs and trees and can be easily swept/beaten from them.
UK Dicranopalpus adults occur in greatest numbers during the late summer and autumn with peaks in August and September, but they are occasionally found in most months of the years, except those of early summer. We do not yet have sufficient information to be able to describe separate phenologies for D. caudatus and D. ramosus.
Hillyard, P. D., & Sankey, J. H. P. 2005. Synopses of the British Fauna (New Series) No. 4: Harvestmen. Third Edition.Field Studies Council, Shrewsbury.
Richards, P. 2010. Guide to Harvestmen of the British Isles. Field Studies Council, Shrewsbury.
Richards, P. 2017. Tabular key for Identification of British Harvestmen (Opiliones). Unpublished.
Wijnhoven, H. 2009. De Nederlandse hooiwagens (Opiliones). Nederlandse Entomologische Vereniging.
Wijnhoven, H. and Prieto, C.E. 2015. Dicranopalpus caudatus Dresco, 1948: Not a synonym of Dicranopalpus Ramosus (Simon, 1909) but a valid species after all (Arachnida, Opiliones). Revista Iberica de Aracnologia, 26: 25-34