<mods:titleid="CC6FC2797E819A53D4154394DCE396E4">Systematic revision of the snorkel snail genus Rhiostoma Benson, 1860 (Gastropoda, Caenogastropoda, Cyclophoridae) with descriptions of new species</mods:title>
<mods:affiliationid="384838B337543B3CD5E3947A8DD5EB4D">Animal Systematics Research Unit, Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand</mods:affiliation>
<mods:affiliationid="938028222CC94BF7A3020A02D81B713E">Animal Systematics Research Unit, Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand & Present address: Department of Biology, Faculty of Science, Mahasarakham University, Kantharawichai, Maha Sarakham 44150 Thailand</mods:affiliation>
<mods:affiliationid="C0CCA3F2ACA1DA407D8CE8A3BA3B8F36">Department of Biology, Faculty of Natural Science, National University of Laos, P. O. Box 7322, Dongdok, Vientiane, Laos</mods:affiliation>
<mods:affiliationid="FB8E7DFD3E05C94A55F7A4D68626EC1C">School of Biology, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand</mods:affiliation>
<mods:affiliationid="EEA226374F1C133EC9E57197831D374C">Animal Systematics and Molecular Ecology Laboratory, Department of Biology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand</mods:affiliation>
<mods:affiliationid="205ED10A922DB29D2C17068FF3D68E84">Animal Systematics Research Unit, Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand</mods:affiliation>
<mods:affiliationid="F398816D1355A618B996F04EF8594274">Animal Systematics Research Unit, Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand</mods:affiliation>
<taxonomicNameid="552614505D0041F264C6C91BDA2DA7EE"ID-CoL="B3CK8"LSID="https://zoobank.org/13B875AD-3E60-431E-B4B2-51F3FC5E03A0"authority="Tongkerd & Tumpeesuwan"authorityName="Tongkerd & Tumpeesuwan"authorityYear="2023"class="Gastropoda"family="Cyclophoridae"genus="Rhiostoma"higherTaxonomySource="treatment-meta"kingdom="Animalia"lsidName="Rhiostoma platymorpha"order="Architaenioglossa"pageId="0"pageNumber="1"phylum="Mollusca"rank="species"species="platymorpha"status="sp. nov.">Rhiostoma platymorpha Tongkerd & Tumpeesuwan</taxonomicName>
<figureCitationid="5B8392A5E871D5FE98ABFE0A3BCB5D21"captionStart="Figure 34"captionStartId="F34"captionText="Figure 34. Distribution map of Rhiostoma asiphon - species group."figureDoi="10.3897/zookeys.1142.90097.figure34"httpUri="https://binary.pensoft.net/fig/799892"pageId="0"pageNumber="1">Figs 34</figureCitation>
<figureCitationid="702B7823B5E860FAD03159F98C6D4BB9"captionStart="Figure 41"captionStartId="F41"captionText="Figure 41. Shell of Rhiostoma platymorpha sp. nov. A holotype CUMZ 4498 / 1 from Tham Muang On, Mae On, Chiang Mai B paratype CUMZ 4763 from type locality C, D paratypes CUMZ 4498 / 2 from type locality E, F specimens CUMZ 4783 from Tham Bua Tong, Mae Tang, Chiang Mai (with F albinistic shell form)."figureDoi="10.3897/zookeys.1142.90097.figure41"httpUri="https://binary.pensoft.net/fig/799899"pageId="0"pageNumber="1">, 41</figureCitation>
<figureCitationid="3DD25EFE189182C8B4E06DFE3C9414D8"captionStart="Figure 42"captionStartId="F42"captionText="Figure 42. Radula morphology A Rhiostoma asiphon CUMZ 4826 from Angthong Islands, Surat Thani B Rhiostoma strubelli specimen CUMZ 10200 from Vieng Phuka, Luang Namtha, Laos C Rhiostoma breviocollar sp. nov. paratypes CUMZ 4491 from type locality D Rhiostoma anceyi sp. nov. paratype CUMZ 4494 / 2 from type locality E Rhiostoma furfurosum sp. nov. paratype CUMZ 4705 / 2 from type locality F Rhiostoma platymorpha sp. nov. paratype CUMZ 4763 from type locality."figureDoi="10.3897/zookeys.1142.90097.figure42"httpUri="https://binary.pensoft.net/fig/799900"pageId="0"pageNumber="1">, 42F</figureCitation>
<taxonomicNameid="6D34EA61D72A73CF82CEBC7F09700161"authority="Tongkerd & Tumpeesuwan & Inkhavilay & Prasankok & Jeratthitikul & Panha & Sutcharit, 2023"authorityName="Tongkerd & Tumpeesuwan & Inkhavilay & Prasankok & Jeratthitikul & Panha & Sutcharit"authorityYear="2023"class="Gastropoda"family="Cyclophoridae"genus="Rhiostoma"higherTaxonomySource="treatment-meta"kingdom="Animalia"lsidName="Rhiostoma"order="Architaenioglossa"pageId="0"pageNumber="1"phylum="Mollusca"rank="genus"status="sp. nov.">Rhiostoma</taxonomicName>
<bibRefCitationid="B3F2B90845C22022F52F873E2B8A9CB9"author="Tumpeesuwan, S"journalOrPublisher="Master Thesis, Department of Biology, Faculty of Science, Chulalongkorn University"pageId="0"pageNumber="1"refId="B175"refString="Tumpeesuwan, S, 2001. Taxonomy of snorkel snails genus Rhiostoma Benson, 1860 in Thailand. Master Thesis, Department of Biology, Faculty of Science, Chulalongkorn University"title="Taxonomy of snorkel snails genus Rhiostoma Benson, 1860 in Thailand."year="2001">Tumpeesuwan 2001</bibRefCitation>
<figureCitationid="3A46243736BD5FDA7186C6231F726260"captionStart="Figure 41"captionStartId="F41"captionText="Figure 41. Shell of Rhiostoma platymorpha sp. nov. A holotype CUMZ 4498 / 1 from Tham Muang On, Mae On, Chiang Mai B paratype CUMZ 4763 from type locality C, D paratypes CUMZ 4498 / 2 from type locality E, F specimens CUMZ 4783 from Tham Bua Tong, Mae Tang, Chiang Mai (with F albinistic shell form)."figureDoi="10.3897/zookeys.1142.90097.figure41"httpUri="https://binary.pensoft.net/fig/799899"pageId="0"pageNumber="1">41A</figureCitation>
<figureCitationid="EF808FB8DF029849A5A7FAF546A0E216"captionStart="Figure 41"captionStartId="F41"captionText="Figure 41. Shell of Rhiostoma platymorpha sp. nov. A holotype CUMZ 4498 / 1 from Tham Muang On, Mae On, Chiang Mai B paratype CUMZ 4763 from type locality C, D paratypes CUMZ 4498 / 2 from type locality E, F specimens CUMZ 4783 from Tham Bua Tong, Mae Tang, Chiang Mai (with F albinistic shell form)."figureDoi="10.3897/zookeys.1142.90097.figure41"httpUri="https://binary.pensoft.net/fig/799899"pageId="0"pageNumber="1">41C, D</figureCitation>
<figureCitationid="068ABACF92A490E78865F5EEE72C2AD4"captionStart="Figure 41"captionStartId="F41"captionText="Figure 41. Shell of Rhiostoma platymorpha sp. nov. A holotype CUMZ 4498 / 1 from Tham Muang On, Mae On, Chiang Mai B paratype CUMZ 4763 from type locality C, D paratypes CUMZ 4498 / 2 from type locality E, F specimens CUMZ 4783 from Tham Bua Tong, Mae Tang, Chiang Mai (with F albinistic shell form)."figureDoi="10.3897/zookeys.1142.90097.figure41"httpUri="https://binary.pensoft.net/fig/799899"pageId="0"pageNumber="1">41B</figureCitation>
<figureCitationid="8267B15189BED4E8E447B6DA546D092E"captionStart="Figure 42"captionStartId="F42"captionText="Figure 42. Radula morphology A Rhiostoma asiphon CUMZ 4826 from Angthong Islands, Surat Thani B Rhiostoma strubelli specimen CUMZ 10200 from Vieng Phuka, Luang Namtha, Laos C Rhiostoma breviocollar sp. nov. paratypes CUMZ 4491 from type locality D Rhiostoma anceyi sp. nov. paratype CUMZ 4494 / 2 from type locality E Rhiostoma furfurosum sp. nov. paratype CUMZ 4705 / 2 from type locality F Rhiostoma platymorpha sp. nov. paratype CUMZ 4763 from type locality."figureDoi="10.3897/zookeys.1142.90097.figure42"httpUri="https://binary.pensoft.net/fig/799900"pageId="0"pageNumber="1">42F</figureCitation>
<taxonomicNameid="C55DE851A1B802A8F10A62C79FFABA88"authorityName="Tongkerd & Tumpeesuwan"authorityYear="2023"class="Gastropoda"family="Cyclophoridae"genus="Rhiostoma"kingdom="Animalia"lsidName="Rhiostoma platymorpha"order="Architaenioglossa"pageId="0"pageNumber="1"phylum="Mollusca"rank="species"species="platymorpha">
<taxonomicNameid="ABB449111B678A41240820CBC9E1FD6B"authorityName="Tongkerd & Tumpeesuwan"authorityYear="2023"class="Gastropoda"family="Cyclophoridae"genus="Rhiostoma"kingdom="Animalia"lsidName="Rhiostoma breviocollar"order="Architaenioglossa"pageId="0"pageNumber="1"phylum="Mollusca"rank="species"species="breviocollar">
<taxonomicNameid="364A10154FAA87703E983C6EA2622873"authorityName="Tongkerd & Inkhavilay"authorityYear="2023"class="Gastropoda"family="Cyclophoridae"genus="Rhiostoma"kingdom="Animalia"lsidName="Rhiostoma anceyi"order="Architaenioglossa"pageId="0"pageNumber="1"phylum="Mollusca"rank="species"species="anceyi">
<taxonomicNameid="F739CEE886A80DC73B0CE2D3EE4C76C7"authorityName="Tongkerd & Panha"authorityYear="2023"class="Gastropoda"family="Cyclophoridae"genus="Rhiostoma"kingdom="Animalia"lsidName="Rhiostoma furfurosum"order="Architaenioglossa"pageId="0"pageNumber="1"phylum="Mollusca"rank="species"species="furfurosum">
<taxonomicNameid="214AFF818E65F95B1E482A44B09C33C1"authorityName="Tongkerd & Tumpeesuwan"authorityYear="2023"class="Gastropoda"family="Cyclophoridae"genus="Rhiostoma"kingdom="Animalia"lsidName="Rhiostoma platymorpha"order="Architaenioglossa"pageId="0"pageNumber="1"phylum="Mollusca"rank="species"species="platymorpha">
<figureCitationid="5F0807CF3F1200A34674581BEC1E019F"captionStart="Figure 41"captionStartId="F41"captionText="Figure 41. Shell of Rhiostoma platymorpha sp. nov. A holotype CUMZ 4498 / 1 from Tham Muang On, Mae On, Chiang Mai B paratype CUMZ 4763 from type locality C, D paratypes CUMZ 4498 / 2 from type locality E, F specimens CUMZ 4783 from Tham Bua Tong, Mae Tang, Chiang Mai (with F albinistic shell form)."figureDoi="10.3897/zookeys.1142.90097.figure41"httpUri="https://binary.pensoft.net/fig/799899"pageId="0"pageNumber="1">41E, F</figureCitation>
<paragraphid="1091054B8B831EA2AB569A95F9AF6D00"pageId="0"pageNumber="1">Shell small, thin, and flattened; detached whorl shorter than apertural width. Shell colour with brownish zigzag patterns on both sides. Breathing device with incomplete tube shape (rarely short tubular) and attached to preceding whorl.</paragraph>
by having a flattened shell, short detached whorl, and brownish zigzag colour pattern, usually on both the dorsal and ventral sides of the shell. In contrast,
Shell small, cW 17.2-20.2 mm, cH 8.8-11.3 mm, thin, and flattened to sub-discoidal shape; detached-whorl length 2.0-6.0 mm. Apex acute; spire nearly flattened to slightly elevated. Whorls 4 to 5, convex, increasing regularly; suture wide and shallow; last whorl rounded and slender. Shell surface with irregular growth lines. Periostracum corneous and transparent. Shell colour with dark to brownish zigzag pattern, and ventral side with paler pattern; narrow dark brown spiral band on periphery. Detached whorl shorter than apertural width and descending. Peristome circular and double; lip slightly thickened and not expanded. Breathing device with incomplete tube shape and its tip usually attached to preceding whorl; outer lip forming a long and nearly closed tube; inner lip with deep incision. Umbilicus widely opened and deep. Operculum calcareous, low cup-shaped, and multispiral (Fig.
<figureCitationid="0A56A44FAD27750C76A3ABA05BBA0B56"captionStart="Figure 41"captionStartId="F41"captionText="Figure 41. Shell of Rhiostoma platymorpha sp. nov. A holotype CUMZ 4498 / 1 from Tham Muang On, Mae On, Chiang Mai B paratype CUMZ 4763 from type locality C, D paratypes CUMZ 4498 / 2 from type locality E, F specimens CUMZ 4783 from Tham Bua Tong, Mae Tang, Chiang Mai (with F albinistic shell form)."figureDoi="10.3897/zookeys.1142.90097.figure41"httpUri="https://binary.pensoft.net/fig/799899"pageId="0"pageNumber="1">41</figureCitation>
. Central tooth with large central cusp and two lateral cusps on each side. Lateral teeth composed of four cusps; central cusp large with pointed tip; two inner cusps with pointed tips; one outer cusp very small. Marginal teeth each composed of three pointed cusps (Fig.
<figureCitationid="520B4CA5EE38BD495B9FFE0422F84B41"captionStart="Figure 42"captionStartId="F42"captionText="Figure 42. Radula morphology A Rhiostoma asiphon CUMZ 4826 from Angthong Islands, Surat Thani B Rhiostoma strubelli specimen CUMZ 10200 from Vieng Phuka, Luang Namtha, Laos C Rhiostoma breviocollar sp. nov. paratypes CUMZ 4491 from type locality D Rhiostoma anceyi sp. nov. paratype CUMZ 4494 / 2 from type locality E Rhiostoma furfurosum sp. nov. paratype CUMZ 4705 / 2 from type locality F Rhiostoma platymorpha sp. nov. paratype CUMZ 4763 from type locality."figureDoi="10.3897/zookeys.1142.90097.figure42"httpUri="https://binary.pensoft.net/fig/799900"pageId="0"pageNumber="1">42F</figureCitation>
<paragraphid="FED759C14426AC3B802D968695E56C8D"pageId="0"pageNumber="1">This new species is known from the type locality, limestone hills in Chiang Mai Province.</paragraph>
<figureCitationid="48624B417DB08A018EF185A71AEDA571"captionStart="Figure 41"captionStartId="F41"captionText="Figure 41. Shell of Rhiostoma platymorpha sp. nov. A holotype CUMZ 4498 / 1 from Tham Muang On, Mae On, Chiang Mai B paratype CUMZ 4763 from type locality C, D paratypes CUMZ 4498 / 2 from type locality E, F specimens CUMZ 4783 from Tham Bua Tong, Mae Tang, Chiang Mai (with F albinistic shell form)."figureDoi="10.3897/zookeys.1142.90097.figure41"httpUri="https://binary.pensoft.net/fig/799899"pageId="0"pageNumber="1">41E, F</figureCitation>
), tend to differ from the type specimen in having sub-discoidal shells. However, the brownish zigzag colour pattern appears on the dorsal and ventral shell surface, and an incomplete tube-shaped breathing device suggests they are closely related to this species. That being noted, a few specimens with monochrome whitish shells also occur in this population; this is probably an albinistic shell (Fig.
<figureCitationid="44B2B50550E08504DE5D245E3E07B5FD"captionStart="Figure 41"captionStartId="F41"captionText="Figure 41. Shell of Rhiostoma platymorpha sp. nov. A holotype CUMZ 4498 / 1 from Tham Muang On, Mae On, Chiang Mai B paratype CUMZ 4763 from type locality C, D paratypes CUMZ 4498 / 2 from type locality E, F specimens CUMZ 4783 from Tham Bua Tong, Mae Tang, Chiang Mai (with F albinistic shell form)."figureDoi="10.3897/zookeys.1142.90097.figure41"httpUri="https://binary.pensoft.net/fig/799899"pageId="0"pageNumber="1">41F</figureCitation>
