Compendium of Bogidiellid Amphipoda Species

Identification, distribution and ecology of Bogidiellids of World

Un caso de simpatria de tres especies del genero Bogidiella (Crustacea, Amphipoda) en el Noroeste Argentino, con la descripcion de dos nuevas especies

Publication Type:Journal Article
Year of Publication:1988
Authors:L. E. Grosso, Fernández H. R.
Journal:Stygologia, Leiden
Volume:4
Issue:1
Pagination:64-78
Keywords:Argentina, phylogeny
Abstract:

Three species of Bogidiella were collected together in the hyporheal of the river Medina, Sierra de Medina (27°01'S 65°04'W) Tucuman, Argentina.
One of the species B. tucumanensis Grosso & Fernandez, 1985 was already known from the Tafí stream, sierras de San Javier, 30 Km to the southwest; the two others are new B. horcomollensis n. sp. has also been collected in Las Cañas river, Sierras de San Javier, 8 km south of the Tafí stream, and B. ringueleti n. sp. has been found in the type locality only. Both new species are described (both sexes).
B. horcomollensis is the most plesiomorphic of these species. It is characterized by the outer lobe of the second maxilla bearing less than 10 spines; the second male pleopod in which the outer plumose seta of the second article is modified into a foliaceous structure with short spinules on the edge; the outer lobe of maxilliped bearing 2 spines; the inner lobe of the second maxilla having the inner spine more developed than the other ones. There are no modifications in the second male uropod in the first male of female uropods, or in the first male pleopod.
B. ringueleti possesses more than 10 spines on the outer lobe of the second maxilla; the second male pleopod is modified as in B. horcomollensis, however it lacks spinules on the edge, but shows a spinulose area in the enlarged basal part; the second male uropod has a shortened and enlarged peduncle and endopod, with a strongly developed hollow spine and another small one which closes the cavity; the telson is longer than wide; the outer lobe of the maxilliped carries 4 spines; the inner lobe of the second maxilla has the inner spines more developed than die others; the first male and female uropods, as well as the first male pleopod do not show modifications.
B. tucumanensis shares similar modifications with the former species in the second male pleopod; like B. ringueleti it has modifications in the second male uropod and it possesses two autapomorphies: slight modifications in the first uropod of both sexes and in the first male pleopod, the exopod of which is shortened and enlarged, the external element of the second article being bent in a right angle.
Through phylogenetic analysis we found that the three species form a monophyletic group sharing the same modification in the second male pleopod. В. ringueleti and B. tucumanensis possess three synapomorphies: the second male uropod with the same modification, the edge of the foliaceous seta of the second male pleopod without spinules and the number of spines of the outer lobe of the second maxilla being 10 or more.
Because of the different combinations of modified appendages and according to recent systematic criteria, the three species belong to three different subgenera: В. horcomollensis belongs to Stygogidiella Stock. В. ringueleti to Dyctiogidiella Grosso & Claps, and В. tucumanensis to Mesochtongidiella Grosso & Fernandez.
A lack of articulation in the palp of the first maxilla of some individuals of B. horcomollensis and B. ringueleti was observed; this variable character was used in the past to establish genera in this family.
The high rate of supernumerary spines in the telson, and the intermediate shapes between the modified male pleopod in mixed populations of В. tucumanensis and the unmodified one is considered a sign of hybridization. Such variations were not observed in isolated populations of B. horcomollensis and B. tucumanensis. B. ringueleti was never found in allopatric situations, and has been described on the basis of individuals without traces of hybrization.
Although the close phylogenetic relationships and lack of exclusion is suggestive of sympatric speciation, the meeting of the three species after differentiation by allopatric speciation before the formation of the Sierra de Medina is considered to be more probable.

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith