Zoological Studies

Vol. 54, 2015

The poorly known genus Ventrifurca Roewer, 1913 revisited (Opiliones: Cranaidae)

Osvaldo Villarreal M1*, Adriano B Kury1 and Ricardo Pinto-da-Rocha2

1Departamento de Invertebrados, Museu Nacional/UFRJ, Quinta da Boa Vista, São Cristóvão, 20.940-040 Rio de Janeiro, RJ, Brazil
2Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo, Caixa Postal 11461, 05422-970 São Paulo, SP, Brazil

Background: The distinction of genera in Cranaidae (as in many other Gonyleptoidea) is traditionally made on the basis of a combination of armature of scutal areas, tarsomere counts, and some secondary sexual structures (which may vary among males). This historically led to the creation of non-natural groups of species as meaningless genera. Here some nominal genera of Cranaidae are addressed, and this paucity of diagnostic characters is alleviated with more detailed diagnoses and descriptions.
The poorly known genus Ventrifurca Roewer, 1913, hitherto monotypic, is revisited. The genera Microcranaus Roewer, 1913 (with three species), Cayabeus Roewer, 1932 (monotypic), and Angistrius (monotypic) are here proposed as junior subjective synonyms of Ventrifurca. Both type species of Microcranaus and Cayabeus are considered junior subjective synonyms of Ventrifurca albipustulata; thus, Cayabeus perlatus Roewer, 1932 and Microcranaus pustulatus Roewer, 1913 = Ventrifurca albipustulata Roewer, 1913. Ventrifurca abnormis comb. nov. is proposed for Angistrius abnormis Roewer, 1932. Rhopalocranaus dybasi Goodnight & Goodnight, 1947, currently Neocranaus dybasi, is transferred to Ventrifurca, and the new combination Ventrifurca dybasi comb. nov. is herein proposed for it. Ventrifurca albipustulata is redescribed, and for the first time, the male genitalia is described and illustrated, and SEM pictures are offered. The new species Ventrifurca caffeinica sp. nov. is described from Quindío department, Colombia. A new diagnosis to Ventrifurca is proposed. The relationships of Ventrifurca are discussed. The remaining two species of Microcranaus are transferred to the family Manaosbiidae: (1) Microcranaus columbianus newly combined as Rhopalocranaus columbianus (Roewer, 1963) and (2) Microcranaus gracilis newly combined as Camelianus gracilis (Roewer, 1913). New diagnoses are given for both species.
Conclusions: A non-monotypic genus of Andean Cranaidae is defined, associated with a well-defined geographic region, and unloaded of extraneous species which belong to another family. Recognition of variation in heteromorphicmales reveals past errors of assignment when only limited samples were available for study.

Key words: Indo-Pacific; Taiwanese; Humpback dolphin; New subspecies; Sousa chinensis taiwanensis; Diagnosability; ‘75% rule’.

*Correspondence: E-mail: osvaldovillarreal@gmail.com