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Gainett G, Sharma PP, Giribet G, Willemart RH. The sensory equipment of a sandokanid: An extreme case of tarsal reduction in harvestmen (Arachnida, Opiliones, Laniatores). J Morphol 2018; 279:1206-1223. [PMID: 29893061 DOI: 10.1002/jmor.20843] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 04/30/2018] [Accepted: 05/05/2018] [Indexed: 12/30/2022]
Abstract
The study of sensory structures has the potential to provide insights into the natural history and evolution of animals. The sensory structures of arachnids are usually concentrated on the pedipalps (the tritocerebral appendages) or on the distal podomere (tarsus) of the anterior walking legs, the latter being the case for armored harvestmen (Opiliones, Laniatores). Therefore, modifications of the tarsus could have direct impacts on the sensory equipment of these animals. Using scanning electron microscopy, we investigated the sensory equipment in an extreme case of reduction in tarsal articles in the harvestman Sandokan truncatus (Sandokanidae), which bears a single tarsomere in all legs, and the potential consequences of this reduction. Additionally, we review the literature on the natural history of the family Sandokanidae. Tarsomeres of all legs are equipped with gustatory sensilla, mechanoreceptors, and a pore organ, but wall-pored olfactory sensilla are restricted to tarsi I and II. Tarsi II present a higher density of olfactory sensilla and also putative campaniform sensilla (strain detectors), which indicates a special sensory function of this pair of legs. Other podomeres are covered with shelled sensilla, a probable chemoreceptor previously unreported in Opiliones. Overall, S. truncatus has types of sensilla largely comparable to harvestmen with longer and subdivided tarsi. However, S. truncatus also exhibits extra-tarsal sensory fields of sensilla basiconica (putative thermo-/hygroreceptors) in previously undescribed sites, and the unique pore organs. Our results establish a basis for further research investigating the natural history, as well as the evolutionary correlations and mechanistic causes of the tarsal reduction in this enigmatic lineage.
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Affiliation(s)
- Guilherme Gainett
- Laboratório de Ecologia Sensorial e Comportamento de Artrópodes, Escola de Artes, Ciências e Humanidades, Universidade de São Paulo, São Paulo, SP, 03828-000, Brazil.,Department of Integrative Biology, University of Wisconsin-Madison, Madison, Wisconsin, 53706, USA
| | - Prashant P Sharma
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, Wisconsin, 53706, USA
| | - Gonzalo Giribet
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, 02138, USA
| | - Rodrigo H Willemart
- Laboratório de Ecologia Sensorial e Comportamento de Artrópodes, Escola de Artes, Ciências e Humanidades, Universidade de São Paulo, São Paulo, SP, 03828-000, Brazil.,Programa de Pós-Graduação em Zoologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, 08-055-090, Brazil.,Programa de Pós-Graduação em Ecologia e Evolução, Universidade Federal de São Paulo, Diadema, SP, 09972-270, Brazil
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The genus Hormiops Fage, 1933 (Hormuridae, Scorpiones), a palaeoendemic of the South China Sea: systematics and biogeography. C R Biol 2014; 337:596-608. [PMID: 25282174 DOI: 10.1016/j.crvi.2014.07.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 07/28/2014] [Accepted: 07/28/2014] [Indexed: 11/23/2022]
Abstract
The monotypic genus Hormiops Fage, 1933 is so far only known from two groups of granitic islands off the coasts of Peninsular Malaysia and Vietnam. Examination of newly collected material from both archipelagos and of the type series of Hormiops davidovi Fage, 1933 reveals previously disregarded morphological differences sufficient to assign the Malaysian specimens to a distinct species, described here as Hormiops infulcra sp. nov. An updated diagnosis of the genus, as well as a dichotomic key enabling the determination of Hormiops from its close relatives, Hormurus Thorell, 1876 and Liocheles Sundevall, 1833 are also provided. The phylogenetic position, distribution pattern, and ecology of these insular scorpions suggest that they are palaeoendemics, remnants of a previously more widely distributed lineage. A biogeographical model is proposed for the genus based on these observations and on a synthesis of palaeogeographical and palaeoenvironmental data currently available for Sundaland.
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Sandokanid phylogeny based on eight molecular markers—The evolution of a southeast Asian endemic family of Laniatores (Arachnida, Opiliones). Mol Phylogenet Evol 2009; 52:432-47. [DOI: 10.1016/j.ympev.2009.03.013] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2008] [Revised: 03/03/2009] [Accepted: 03/07/2009] [Indexed: 11/19/2022]
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