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Studies on spider nomenclature II: a synonymy and misidentification in Asian Pholcus Walckenaer, 1805 (Araneae: Pholcidae)

The genus Pholcus Walckenaer, 1805 contains some of the best-known species of Pholcidae, a family colloquially referred to as daddy long-legs spiders. Following the ground-breaking revision of Pholcus by Huber (2011), several further papers from Huber and his colleagues (e.g.
Huber, Nuñeza & Leh Moi Ung 2016; Huber et al. 2016a–b), and publications from other labs have appeared in the last few years (e.g. Lee et al. 2021; Yao, Wang & Li 2021; Lu et al. 2023; Zhao et al. 2023). Indeed, Pholcus is the most widespread and speciose pholcid genus with 408 species currently valid (World Spider Catalog 2024).

Huber (2011) described 112 species new to science in a single paper, including 89 belonging to Pholcus. Furthermore, Huber (2011) synonymized seven species, revalidated one species from synonymy, transferred three species into the genus from other genera, and conversely transferred another three species from Pholcus to other genera. As part of this work, he described a new species from Malaysia, Pholcus kohi Huber, 2011, based on a holotype male from Malaysia, and redescribed Pholcus gracillimus Thorell, 1890. However, Huber stressed that he was not able to
examine the holotype male of P. gracillimus and thus indicated that his identification of non-type material as this species should be considered tentative. Yao, Tavano & Li (2013) were able to examine the male of P. gracillimus and redescribed this species, noting its morphology was divergent from the material assigned to this name by Huber (2011). They also suggested that P. kohi may be a junior synonym of P. gracillimus sensu stricto, but made no formal synonymy, stressing they had not examined the type material. It is important to add that Huber and colleagues were aware of this issue thereafter, with the species names P. gracillimus and P. kohi both placed in quotation marks in their molecular phylogenetic trees in subsequent papers (i.e. Eberle et al. 2018; Huber, Eberle & Dimitrov 2018).

However, the excellent photographs, drawings, and description of the holotype of P. kohi, in our opinion, negate the need to directly examine the type, as all taxonomically informative characters are clearly seen. Since Yao, Nie & Li (2019), more than 130 taxonomic publications on Pholcidae have been published (World Spider Catalog 2024) including a significant number of new Pholcus from Southeast Asia but the aforementioned nomenclatural issues have not been addressed. Thus, it was prudent that the possible misidentification discussed by Yao, Tavano & Li (2013) be reexamined.

In this work, the synonymy suggested by Yao, Tavano & Li (2013) is confirmed and proposed formally. Furthermore, the material tentatively identified by Huber (2011) as P. gracillimus is determined to be a new species, matching no species known at the time of Huber (2011), nor any of the Pholcus species described after 2011. It is thus formally described herein and nomenclatural implications for the naming of informal species groups in Pholcus is given. Type material of the new species is deposited in the Naturalis Biodiversity Centre, Leiden, The Netherlands (RMNH) and the California Academy of Sciences, San Franciso, United States of America (CAS). The holotype of P. gracillimus is deposited in the Museo Civico di Storia Naturale ‘Giacomo Doria’, Genova, Italy (MSNG). Non-type material is deposited in the Museum Koenig, Leibniz Institute for the Analysis of Biodiversity Change, Bonn, Germany (ZFMK). Since this is a nomenclatural work being made with Article 13.1.2 of the International Code of Zoological Nomenclature (ICZN, 2012), which allows us make a description using the previously published data of B. A. Huber, we did not directly examine the types or other specimens listed herein except for the holotype of P. kohi which was imaged by H-JK by request of DS. Instead, we relied on the published data and further previously unpublished results gathered by B. A. Huber and kindly shared with us for this work.

Authors: Danniella SHERWOOD & Hans-Joachim KRAMMER

See the World Spider Catalog for further details.

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The genus Pholcus Walckenaer, 1805 contains some of the best-known species of Pholcidae, a family colloquially referred to as daddy long-legs spiders. Following the ground-breaking revision of Pholcus by Huber (2011), several further papers from Huber and his colleagues (e.g.
Huber, Nuñeza & Leh Moi Ung 2016; Huber et al. 2016a–b), and publications from other labs have appeared in the last few years (e.g. Lee et al. 2021; Yao, Wang & Li 2021; Lu et al. 2023; Zhao et al. 2023). Indeed, Pholcus is the most widespread and speciose pholcid genus with 408 species currently valid (World Spider Catalog 2024).

Huber (2011) described 112 species new to science in a single paper, including 89 belonging to Pholcus. Furthermore, Huber (2011) synonymized seven species, revalidated one species from synonymy, transferred three species into the genus from other genera, and conversely transferred another three species from Pholcus to other genera. As part of this work, he described a new species from Malaysia, Pholcus kohi Huber, 2011, based on a holotype male from Malaysia, and redescribed Pholcus gracillimus Thorell, 1890. However, Huber stressed that he was not able to
examine the holotype male of P. gracillimus and thus indicated that his identification of non-type material as this species should be considered tentative. Yao, Tavano & Li (2013) were able to examine the male of P. gracillimus and redescribed this species, noting its morphology was divergent from the material assigned to this name by Huber (2011). They also suggested that P. kohi may be a junior synonym of P. gracillimus sensu stricto, but made no formal synonymy, stressing they had not examined the type material. It is important to add that Huber and colleagues were aware of this issue thereafter, with the species names P. gracillimus and P. kohi both placed in quotation marks in their molecular phylogenetic trees in subsequent papers (i.e. Eberle et al. 2018; Huber, Eberle & Dimitrov 2018).

However, the excellent photographs, drawings, and description of the holotype of P. kohi, in our opinion, negate the need to directly examine the type, as all taxonomically informative characters are clearly seen. Since Yao, Nie & Li (2019), more than 130 taxonomic publications on Pholcidae have been published (World Spider Catalog 2024) including a significant number of new Pholcus from Southeast Asia but the aforementioned nomenclatural issues have not been addressed. Thus, it was prudent that the possible misidentification discussed by Yao, Tavano & Li (2013) be reexamined.

In this work, the synonymy suggested by Yao, Tavano & Li (2013) is confirmed and proposed formally. Furthermore, the material tentatively identified by Huber (2011) as P. gracillimus is determined to be a new species, matching no species known at the time of Huber (2011), nor any of the Pholcus species described after 2011. It is thus formally described herein and nomenclatural implications for the naming of informal species groups in Pholcus is given. Type material of the new species is deposited in the Naturalis Biodiversity Centre, Leiden, The Netherlands (RMNH) and the California Academy of Sciences, San Franciso, United States of America (CAS). The holotype of P. gracillimus is deposited in the Museo Civico di Storia Naturale ‘Giacomo Doria’, Genova, Italy (MSNG). Non-type material is deposited in the Museum Koenig, Leibniz Institute for the Analysis of Biodiversity Change, Bonn, Germany (ZFMK). Since this is a nomenclatural work being made with Article 13.1.2 of the International Code of Zoological Nomenclature (ICZN, 2012), which allows us make a description using the previously published data of B. A. Huber, we did not directly examine the types or other specimens listed herein except for the holotype of P. kohi which was imaged by H-JK by request of DS. Instead, we relied on the published data and further previously unpublished results gathered by B. A. Huber and kindly shared with us for this work.

Authors: Danniella SHERWOOD & Hans-Joachim KRAMMER

See the World Spider Catalog for further details.