Phylogeny of the clade K92 (Opiliones, Laniatores, Gonyleptidae) with description of a new subfamily and discussion on the evolution of caelopygine facies and sexual dimorphism

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2022-05-01

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Background: K92 is a clade of Gonyleptidae harvestmen of which the greatest diversity lies within the large non-monophyletic subfamily Gonyleptinae. K92 formally includes five subfamilies: Caelopyginae Sørensen, 1884, Gonyleptinae Sundevall, 1833, Hernandariinae Sørensen, 1884, Progonyleptoidellinae Soares & Soares, 1985 and Sodreaninae Soares & Soares, 1985. The basic taxonomy of K92 presently finds itself in an unsatisfactory state, with many species poorly known and supraspecific taxa defined by a combination of few trivial and/or misconstrued features. Questions: Three lines of investigation regarding K92 are pursued in this project: (1) some formal gonyleptine genera, such as Liogonyleptoides Mello-Leitão, 1925 and Parapachyloides Roewer, 1913a were suspected to be especially related to each other as members of an undiscovered non-gonyleptine taxon. Do those species, distributed along the semi-arid diagonal in South America plus the Atlantic Forest in eastern Brazil really form a clade? (2) Has the acquisition of the caelopygine facies by species of Progonyleptoidellinae and Sodreaninae been gradual and independent, associated with diurnal and arboreal habits? (3) Does the attenuation of sexual dimorphism present in K92 have a phylogenetic signal? Methods: A cladistic analysis of some critical taxa in K92 is performed by means of maximum parsimony and Bayesian inference. A matrix with 112 morphological characters and 61 terminals has been analyzed for this project, focusing on (a) potential relatives of Liogonyleptoides, and (b) species of K92 with varied degrees of sexual dimorphism. Main results: For question (1), a phylogenetic hypothesis is proposed herein for the larger clades of K92 as follows: (a) a branch in the phylogeny of K92 is here recognized and formally described as the new subfamily Cearininae. The Cearininae subfam. nov. includes the following genera: Cearinus Roewer, 1929 (type genus), Inhuma Piza, 1938, Liogonyleptoides Mello-Leitão, 1925 (incl. Pachyleptes Mello-Leitão, 1932), Pajeuia gen. nov., Parapachyloides Roewer, 1913b and Ypsilonurus Mello-Leitão, 1933a. (b) Gonyleptinae did not resolve here as a clade. (c) A monophylum never reported before is recovered here (clade I, here nicknamed CAPS), consisting of the nominal subfamilies Caelopyginae, Progonyleptoidellinae and Sodreaninae. Progonyleptoidellinae is polyphyletic. All of these subfamilies have their internal composition altered. For question (2), we found that the caelopygine facies (diurnal, arboreal, triangular bodied, brightly colored animals with long legs, high tarsal counts and pectinated claws) probably arose independently in (a) the classic Caelopyginae (including pectinated tarsal claws, the full caelopygine facies), (b) partial caelopygine facies of extended Sodreaninae, as represented by Heliella, and (c) partial caelopygine facies of extended Caelopyginae, as represented by Progonyleptoidellus. For question (3), we found that attenuated sexual dimorphism may evolve via two different processes: females acquiring armature and males losing armature. The three different forms of sexual dimorphism provided insight to the phylogeny of K92: (a) strong sexual dimorphism, where females are plump and unarmed at leg IV in contrast with lean and strongly armed males is typical for most members of K92 and other Gonyleptidae and is the primitive condition; (b) a process of masculinization, where the lean, polygonal females resemble males, only with the armature of leg IV somewhat attenuated, occurs in some Caelopyginae and Progonyleptoidellinae in the traditional sense and reaches the most extreme degree in the members of the genus Moreiranula Roewer, 1930; (c) a process of feminization, where males have weakly developed coxa IV, no differential armature on leg IV, and are almost indistinguishable from the females. This occurs in some Hernandariinae such as Piassagera Roewer, 1929, one species of Moreiranula and some Progonyleptoidellinae, such as Iporangaia Mello-Leitão, 1935a and Mitopernoides B. Soares, 1945, and one Caelopyginae strictu sensu, Thereza Roewer, 1943. Other taxonomic results: As byproducts of this project, not direct consequences of the phylogenetic analysis, taxonomic changes are proposed for some genera and species in K92. For conciseness, the equality sign (x = y) is here used instead of the expression “x is here newly considered a junior subjective synonym of y”: (1) Cearinus was hitherto monotypic. A second species is described here – Cearinus torulosus sp. nov. – from Mato Grosso State, Central Brazil. (2) Liogonyleptoides is reviewed. There are currently 5 species included, of which one (Liogonyleptoides heliae Kury 2003) is a species inquirenda, another is a synonym (Liogonyleptoides capichaba = Liogonyleptoides tetracanthus) and a third (Liogonyleptoides minensis) is here transferred to the new monotypic genus Pajeuia. A new diagnosis of the genus Liogonyleptoides is proposed and emended diagnoses are given to Liogonyleptoides inermis and L. tetracanthus. Two new species are described in Liogonyleptoides – Liogonyleptoides mirificus sp. nov. and Liogonyleptoides venatus sp. nov., from northern Espírito Santo. (3) Inhuma Piza, 1938, hitherto monotypic, is expanded to include another three species, each of which originally constituted a monotypic genus. Accordingly, the genera Schubartesia B. Soares, 1944a, Hugoesia H. Soares 1968 and Stefanesia Soares and Soares, 1988 all = Inhuma. (4) Metagonyleptes Roewer, 1913a is dismantled, the genus is newly considered a junior subjective synonym of Mischonyx Bertkau, 1880 (because the synonymy of the type species), while its species are transferred to varied genera, notably to Guascaleptes (herein revalidated from the synonymy with Geraeocormobius Holmberg, 1887) and to the undescribed genera SOD-01 and SOD-02. (5) Gonyleptes carinatus Sørensen, 1884 (type species of Metagonyleptes) = Gonyleptes scaber Kirby 1819 (currently Mischonyx scaber (Kirby 1819)). (6) Geogonys Mello-Leitão 1937, currently a synonym of Metagonyleptes, is newly transferred to the synonymy of Guascaleptes Mello-Leitão, 1933b to include some species formerly in Metagonyleptes. (7) Geogonys pallidipalpis Mello-Leitão, 1937, type species of Geogonys and currently a valid species of Metagonyleptes is newly synonymized with Metagonyleptes grandis Roewer, 1913b, both newly combined under Guascaleptes. (8) Gonyleptes saprophilus Mello-Leitão, 1922 and Sodreana curupira Pinto-da-Rocha and Bragagnolo, 2011 are newly transferred to Moreiranula Roewer, 1930, forming the new combinations Moreiranula saprophila and Moreiranula curupira. (9) Gonyleptes espiritosantensis B. Soares, 1944a = Proctobunoides tuberosus Mello-Leitão, 1944.

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Zoologischer Anzeiger, v. 298, p. 70-122.

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