Phylogeny of Opiliones In Figs. 1 to 11, the most relevant hypotheses (or extrapolations) found in the literature concerning the branching pattern of the Opiliones are presented. The five following genera are here used to represent the major groups of Opiliones as currently understood: Siro (for the Cyphophthalmi), Gonyleptes (for the Laniatores), Phalangium (for the Phalangioidea), Ischyropsalis (for the Ischyropsalidoidea) and Trogulus (for the Troguloidea) (see also Table 2 for details). The unity of Opiliones (Hypothesis O 1, Fig. 1), as currently used, was established by Latreille (1802) and has never been seriously challenged except when Sundevall (1833) (and much later, Savory 1977) separated the Cyphophthalmi from the other Opiliones. Hypothesis O 2 (Fig. 2), by Sundevall (1833), was a step back from the work of Latreille (1802), who had included Siro in the Opiliones, under the name “Phalangiens”. The taxa within Opiliones were regarded as coordinate families, without resolution. A strange variation of this may be found in Perty (1833) and Gervais (1844), where part of the Laniatores (the Cosmetidae only) is included along with Phalangium among the nongonyleptid Opiliones. These were the only attempts to challenge the monophyly of the Laniatores. Hypothesis O 3 (Fig. 3), by Thorell (1876), launched the Palpatores, a name that would frequently be used later with a different concept (equaled to the Plagiostethi, see below). At the same time, Thorell, following the then recent work of Sørensen (1873) united the groups that would be much later called the Dyspnoi, a concept that was widely disclaimed, but prevails today. Hypothesis O 4 (Fig. 4), by Simon (1879), defined the Plagiostethi, a name that afterwards was extensively (and wrongly) regarded as a less-favored synonym of Palpatores. This concept is favored until now in recent analyses, although under the name “Palpatores hypothesis”. Hypothesis O 5 (Fig. 5), proposed by Pocock (1902) and espoused by Loman (1903), maintained Simon’s Plagiostethi, refining their inner relationships by creating the Apagosterni, a clade not supported by the most recent analyses (e.g., O 10, O 11). Hypothesis O 6 (Fig. 6), proposed by Hansen & Sørensen (1904), also kept Plagiostethi, but changed their inner relationships by recovering (and for the first time naming) Thorell’s Dyspnoi. This classical hypothesis has been used during most of the 20th century. Hypothesis O 7 (Fig. 7), proposed by Mello-Leitão (1944), was presented as a branching cactus instead of the standard “tree” (see reproduction in Giribet & Kury 2007). Mello-Leitão managed to combine the concepts of Cyphopalpatores, Palpatores and Apagosterni into a single hypothesis. It did not gain much favor. Hypothesis O 8 (Fig. 8), proposed by Šilhavý (1961), was a large step back, because it did not contain any branching information besides keeping the Dyspnoi. For this reason, it was heavily criticized by Shear (1975). Hypothesis O 9 (Fig. 9), proposed by Martens (1980), was the first cladistic analysis of Opiliones, representing a development of his earlier work (Martens 1976). It was non-numerical, used only a few morphological characters, and did not use real outgroups. However, it represented an immense advance in relation to the status quo and because of its solid scientific content, was target to many critics (see for example extended criticism in Shultz 1998: 257-258). Martens’ (1980) hypothesis resembled Mello-Leitão’s hypothesis O 7 in that it retrieved the Palpatores (there called “Cyphopalpatores”, because Palpatores was then held as a synonym of Plagiostethi) and the Apagosterni. Hypothesis O 10 (Fig. 10) is the classic molecular hypothesis, defended in Shultz & Regier (2001) and Giribet et al. (2010). Also supported by the purely morphological analysis by Shultz (1998), it resurrected the original Opiliones concept, by making the Cyphophthalmi the sister group of all other Opiliones (called “Phalangida” by Giribet et al. 1999). It also recovered the Palpatores and the Dyspnoi. Hypothesis O 11 (Fig. 11) is recovered by the two only combined molecular + morphological analyses conducted so far (Giribet et al. 1999; 2002), which recovered Lehtinen’s (1975) Phalangida (= Sundevall’s Opiliones), and for the first time proposed a sister group relationship of the Eupnoi against the rest of Phalangida (named Dyspnolaniatores by Giribet), something hinted at by Lehtinen (1975).

Published as part of Kury, Adriano B., 2015, Opiliones are no longer the same — on suprafamilial groups in harvestmen (Arthropoda: Arachnida), pp. 301-340 in Zootaxa 3925 (3) on pages 305-316, DOI: 10.11646/zootaxa.3925.3.1, http://zenodo.org/record/287978