Clarification on the name-bearing type designation of several cyclophorid species (Mollusca, Gastropoda) by H. H. Godwin-Austen (1915)

Abstract The type series boundary and the name-bearing type designation of each cyclophorid taxon originally described by Godwin-Austen are clarified based on an interpretation that complies with the ICZN. Previous statuses of type specimens designated by previous authors are reconsidered. Lectotypes of Spiraculum oakesi Godwin-Austen, 1915, Spiraculum kempi Godwin-Austen, 1915, Pterocyclos aborensis Godwin-Austen, 1915, Pterocyclos miriensis Godwin-Austen, 1915, Pterocyclos brahmakundensis Godwin-Austen, 1915, Spiraculum luyorensis Godwin-Austen, 1915, Spiraculum putaoensis Godwin-Austen, 1915, and Theobaldius oakesi Godwin-Austen, 1915 are here designated to stabilize the existing nomenclature. In addition, the type specimens of Pterocyclos miriensis and Theobaldius oakesi are photographed and figured for the first time.


Introduction
The phylogenetic analyses of the operculated land snail genus Cyclophorus (Caenogastropoda: Cyclophoridae) from Thailand uncovered a high degree of intra-and interspecific morphological variation and a wide distribution of the genus (Nantarat et al. 2014b, c;. Southeast Asia, including Thailand, also hosts a high diversity of related cyclophorid genera, such as Pterocyclos Benson, 1832, Spiraculum Pearson, 1833 (= Pearsonia Kobelt, 1902), and Rhiostoma Benson, 1860, in which the members of each genus are conchologically very similar (BEDO 2017;Sutcharit et al. 2018), and for which precise species identification is not possible without direct comparison with the type specimens.
The Natural History Museum in London (hereafter the NHM) holds the type specimens of 42 nominal Cyclophorus species (Nantarat et al. 2014a), which is approximately a quarter of all currently recognized species (Kobelt 1902(Kobelt , 1908. The type specimens of 95 nominal species in six other cyclophorid genera, namely Crossopoma Martens, 1891, Cyclotus Swainson, 1840, Myxostoma Troschel, 1847, Pterocyclos, Scabrina Blanford, 1863 Rhiostoma are also housed in the NHM , and constitute about half of all currently known nominal species of these genera (Kobelt 1902). These type specimens have already been catalogued and illustrated, and in certain cases lectotypes were designated in accordance with the International Code of Zoological Nomenclature (ICZN 1999) to stabilize the usage of each nominal name (Nantarat et al. 2014a;Sutcharit et al. 2019).
Of the type specimens housed in the NHM, the cyclophorid taxa originally described in the "Zoological Results of the Abor Expedition" by Godwin-Austen (1915) require special consideration as the original descriptions contain the explicit designation of "Type" and specimen lot numbers (which correspond to the NHMUK registration numbers; note: NHM is the institutional acronym, whilst NHMUK is the registration number prefix of samples kept at the NHM). This way of type designation was not applied in the other works of Godwin-Austen in the same series (Godwin-Austen 1914b, 1916, 1917, 1918a. In contrast, the type lot numbers were explicitly designated in the original descriptions of some taxa in other monographs by Godwin-Austen (1910, 1914a, 1920. Consequently, the interpretation of Godwin-Austen's type series boundaries and the designation of the name-bearing type(s) is often contentious (Nantarat et al. 2014a;Sajan et al. 2019).
In this article, we review the type status of all cyclophorid taxa originally described by Godwin-Austen (1915). Some lectotype designations by Nantarat et al. (2014a) and Sutcharit et al. (2019) and the type status of Cyclophorus koboensis as recognized by Sajan et al. (2019) are reconsidered as we clarify the boundaries of the type series and the name-bearing type designation of each taxon.

The problem with the name-bearing type designations in Godwin-Austen (1915)
When Godwin-Austen (1915) introduced new taxa, he explicitly placed the word "Type" in the beginning of the first paragraph below the shell description and dimen-sions (hereafter regarded as the "Type" paragraph), and this was followed by the specimen lot number belonging to either "Ind. Mus.", currently The National Zoological Collection of the Zoological Survey of India (hereafter the NZSI), or "B.M." referring to the 'British Museum (Natural History)' as it was then known (currently the NHM). However, the original descriptions of some taxa contained more than one specimen lot number, either separated by a semicolon in the same paragraph or appearing in subsequent paragraphs. In addition, for some taxa Godwin-Austen (1915) provided figures of more than one specimen from different specimen lots, but associated the word "Type" in the plate caption to the figures of one specimen only. Therefore, to clarify the name-bearing type designation by Godwin-Austen (1915), it is necessary to answer the following two questions, with verbatim applicable definitions and articles from the fourth edition of the ICZN online version (ICZN 1999)  Godwin-Austen (1915) did not explicitly indicate which specimens were included or excluded from the type series, as he did not use terms such as "syntypes", "cotypes", "types", "type and cotypes" or "holotype and paratypes", while he did refer to other specimens, so that the actual type series cannot be unequivocally delimited using Art. 72.4.6. Therefore, based on Art. 72.4.1., the type series of each taxon recognized by Godwin-Austen (1915) should consist of all specimen lots mentioned in the original description, except any that the author referred to as distinct variants.
According to Art. 72.4.1.1, additional evidence found within or outside the original descriptions, either published or unpublished, may be considered when determining which specimens constitute a type series. Yet, if we do so for the type material of Godwin-Austen (1915), then we are confronted with the following situation. On the one hand, for taxa of which more than one specimen from multiple specimen lots were illustrated, each specimen which was marked as "Type" in the plate captions ( Fig. 1) always belongs to the first lot in the "Type" paragraph (Figs 2, 3) and this first specimen lot was always labelled as "Type" in Godwin-Austen's handwriting (Figs 4A, 5A and Sajan et al. 2019: fig. 1h). On the other hand, specimens from other specimen lots, either in the text delimited from the first lot by a semi-colon or mentioned in subsequent paragraphs, are never marked as "Type" in the plate captions ( Fig. 1) or elsewhere in the text. Likewise, these other specimen lots were never labelled as "Type" (Fig. 5B, C), although they may be marked as "Co-Type", "Typic", or "Typical" in Godwin-Austen's handwriting (Figs 4B,6). According to Art. 72.4.7., the mere citation of "Type" or its equivalent expression on a label does not by itself indicate that those specimens are fixed as any of the kinds of types. In addition, the labels "Typic" and "Typical" did not always relate to type material in the current sense of the word (see Raheem et al. 2014). Therefore, one can argue to restrict the type series of Godwin-Austen's (1915) taxa to the first and only specimen lot in the "Type" paragraph.
These two possible interpretations of the type series are rooted in the ambiguous usage of the "type" terminology in the 19 th century. The term "type" had been given three operational functions by Simpson (1940) as: "(a) a sample from which the characters of a group of individuals or a population are estimated, (b) a standard of comparison between samples, or (c) name-bearers" (Melville 1970). The first two are taxonomic functions of type, while the third one is the nomenclatural function (Dubois 2005). As such, Simpson (1940) introduced the term "hypodigm" for the first two taxonomic functions, meaning "all the specimens used by the author of a species as his basis for inference, and this should mean all the specimens that he referred to the species, constitute his hypodigm of that species". For the third function of "types", i.e., as name-bearers, several terms were proposed, two of which, "onomatophore" (Simpson 1940) and "nomenifer" (Schopf 1960), have been more frequently adopted (e.g., Dubois 2005;Sluys 2021). Here we will use the term "onomatophore" to refer to the name-bearer simply because this term was introduced first.
The ICZN regulates the nomenclatural rules but is not involved in "restricting the freedom of taxonomic thought or actions" (ICZN 1999). Hence, the ICZN is supposed to only deal with rules regulating onomatophores, not with rules that regulate the function of "types" as "hypodigm". However, in Art. 72.4.1. the definition of the type series is identical to that of Simpson's (1940) hypodigm. Consequently, according to Art. 73.2., for all taxa originally described before 2000 and for which neither a holotype, nor a lectotype has been fixed, the Code automatically equates the original hypodigm (= all specimens in the type series) with onomatophores (= syntypes). So, the application of this article is problematic because the word "type" in the term "type series" does not have the same function as in the term "name-bearing type", as was recognized earlier (Melville 1970). This misunderstanding that the name-bearing type possesses taxonomic functions, in being "a typical example, a prototype, or an archetype of the species to which it belongs and to which it affixes a name" still prevails to this day (Sluys 2021). See Witteveen (2016) for more details on the development of the type concept in both taxonomic and nomenclatural functions.
The problem of defining Godwin-Austen's (1915) type series arises because we posit that Godwin-Austen (1915) assigned specimens to the original hypodigm and onomatophores differently. The type series, as defined by Art. 72.4.1., corresponds well to the hypodigm concept. Accordingly, Godwin-Austen (1915) in establishing the original hypodigm applied the terms "Typic" or "Typical" on the label of some specimen lots mentioned in the original description. However, the term "Type" in the sense of onomatophore, as recognized by Godwin-Austen (1915), cannot apply to all specimens in the type series because accepting all specimens in the type series as types  would contradict the writing structure of Godwin-Austen's (1915) original descriptions, plate captions, and the labels of the specimens. As such, the onomatophores as recognized by Godwin-Austen (1915) are limited to the first and only specimen lot in the "Type" paragraphs and corresponding to the labels in Godwin-Austen's handwriting of the respective specimen lots.
Godwin-Austen's (1915) interpretative "type" problem is illustrated by Spiraculum kempi. Two specimen lots, "No. 3105 B.M." from Abor Hills and "No. 3047 B.M." from Ponging, were mentioned in the original description so these two lots constitute the original hypodigm and become the type series. However, only the specimen from lot "No. 3105 Brit. Mus." was marked as "Type" in the plate caption ( Fig. 1B) and this lot was labelled as "Type" in Godwin-Austen's handwriting (Fig. 4A). In contrast, specimen lot "No. 3047 B.M." was not marked as "Type" in the plate caption and was labelled as "Typic." in Godwin-Austen's handwriting (Fig. 4B). Thus, this could mean that Godwin-Austen (1915) designated only lot "No. 3105 B.M." as onomatophores, but not lot "No. 3047 B.M.". However, without an explicit holotype designation or any equivalent expression (see below), the Code dictates that all specimens in both lots constitute the type series and so automatically become syntypes.
Consequently, following Art. 72.4.1. the type series cannot be restricted to only the first lot in the type paragraph, and this action corresponds well to the hypodigm as recognized by Godwin-Austen (1915). However, as the Code automatically equates the original hypodigm to onomatophores if there is no holotype designation, it is possible that a subsequent author selects a lectotype from a syntype that is not part of the originally intended onomatophores, but that is part of the original hypodigm. This has happened with Spiraculum minimum when Sutcharit et al. (2019) designated a specimen that was not part of the originally intended onomatophores as lectotype (see below), an action that is deemed valid under the Code. 2) Are there indications in the holotype designation that comply with an "equivalent expression"? The indication whether the holotype designation of each taxon comply with an "equivalent expression" is a crucial point because if the original author explicitly designated only one onomatophore (= holotype), that holotype designation would comply with the Code and there would be no contradiction in accepting a type (series) as the original hypodigm. Unfortunately, Godwin-Austen (1915) used the term "Type" instead of "Holotype", and although the term "holotype" had already been coined in the late 19 th century (Schuchert 1897), it was not commonly used until the 1950s.  For example, Simpson (1940) and Newell (1949) still used the term "Type", although they mentioned "Holotype" in their works, whereas Shenefelt (1959), Schopf (1960), and Simpson (1960) did apply the term "Holotype". However, in some taxa Godwin-Austen (1915) additionally referred to "the type" in the body of texts. It is, therefore, necessary to demonstrate whether Godwin-Austen (1915) applied "the type" in the sense of a holotype or as an equivalent expression of a holotype designation.
We identified four ways of type annotation by Godwin-Austen (1915). The first way is the most prevalent among his original descriptions, i.e., those for which multiple specimen lots are mentioned in the description, whereas only one specimen is figured and marked as "Type" in the plate caption. This way of type annotation is not an equivalent expression of a holotype designation, as it can refer to any "Type" rather than specifically to "Holotype", while it does not unequivocally imply a single specimen. This interpretation is similar to that of some taxa listed by Cowie et al. (2017) (e.g., fraternus Pilsbry & Bequaert, 1927). In addition, parallel to a lectotype designation before 2000 (ICZN 1999: Arts. 74.5., 74.6.), the expression "Type" does not a priori demonstrate that an author regarded a given specimen as a unique, name-bearing type, and simply figuring a specimen with a "Type" caption is not enough to change this (Welter-Schultes 2013; Calhoun 2017). Therefore, in such cases all specimens in the type series are syntypes and all have an equal nomenclatural status as name-bearing types.
The second way of type annotation by Godwin-Austen (1915) occurs in the original description of Spiraculum kempi, which mentions two specimen lots (Fig. 3). Two specimens, each from a different lot, were figured but only one specimen was marked as "Type" in the plate caption (Fig. 1B). Although this way of type annotation is more specific in pinpointing a single specimen of a particular lot, the expression "Type" still does not necessarily indicate a unique, name-bearing type selected by the original author. Moreover, the specimen lot to which the specimen marked as "Type" in the plate caption belongs, contains more than one specimen. Thus, following Recommendation 73F to avoid the assumption of a holotype, we regard all the specimens in the type series as syntypes.
The third way of Godwin-Austen's (1915) type annotation occurs in Cyclphorus koboensis and is an extension of the second way, in that a set of shell measurements was added to each specimen lot number in the "Type" paragraph (and subsequent paragraphs) (Fig. 2B). In all the other taxa, these measurements were provided in their own lines above the "Type" paragraph (e.g. , Figs 2A, 3). The "Type" annotation in C. koboensis is an equivalent expression of a holotype designation similar to some cases in Cowie et al. (2017) (e.g., langi Pilsbry & Bequaert, 1927and planogyra Pilsbry, 1933. Finally, the fourth way of type annotation occurs in the original description of Cyclophorus aborensis. Two specimens were figured in the plate but only one specimen was marked as "Type" in the plate caption (Fig. 1A), and this specimen belongs to the specimen lot number with the number one under the horizontal fraction bar ( Fig. 2A). This is an equivalent expression of a holotype designation as the number under the horizontal fraction bar is commonly used to represent the number of the specimen in that lot, and this means that only one specimen was designated as the type by Godwin-Austen (1915).
Although Godwin-Austen (1915) referred to "the type" in the body of the text of the original descriptions of C. aborensis and S. kempi, this should not be taken as implying only one single individual. It is more likely that "the type" in Godwin-Austen's sense indicated an association to one specimen lot, which sometimes contains more than one specimen (e.g., S. kempi).

Status of Godwin-Austen's (1915) cyclophorid taxon name-bearing type(s)
The order of taxa below follows that of Godwin-Austen (1915) and the recent species combination follows MolluscaBase (2021). A summary is given in Table 1.

Cyclophorus (Glossostylus) sidiensis Godwin-Austen, 1915
Cyclophorus (Glossostylus) sidiensis Godwin-Austen, 1915: 495, pl. 38, fig. 3 The type series of this species comprises three specimen lots. Without any explicit holotype designation or equivalent expression, all specimens in these three lots are syntypes. However, only specimen lot "No. 6002 Ind. Mus." was mentioned in the "Type" paragraph, and one specimen from this lot was figured with the annotation "Type" in the plate caption. This specimen lot is, therefore, the onomatophore as originally intended by Godwin-Austen (1915). Subsequent authors should select that particular figured specimen from lot NZSI M.6002 as the lectotype. There is one additional specimen lot (NHMUK 1903.7 .1.3095; Fig. 7C) that contains syntypes, but currently this lot could not be located in the NHM.
Specimen "No. 6015 Ind. Mus." (NZSI M.6015/1) is deemed the holotype fixed by original designation as explained above. All specimens in the remaining lots are paratypes, except for lot "No. 3581 B.M." of which Godwin-Austen (1915) stated that it "comes very close to this spices [sic; species]". We regard this as a doubtful attribution (ICZN 1999: Art. 72.4.1). The status of the type series and of the holotype has been correctly clarified by Sajan et al. (2019), whereas the designation of a lectotype and paralectotypes from lot NHMUK 1903.7.1.3579, labelled with "Co-Type" in Godwin-Austen's handwriting (Fig. 6B) and recorded as "CoT" in the Register of Godwin-Austen (Fig. 7D), by Nantarat et al. (2014a) is invalid. The type locality of this taxon is retained and restricted to "Abor Hills, Kobo, on right bank of Tsanspu or Brahmaputra River" only.

Spiraculum oakesi Godwin-Austen, 1915
Spiraculum oakesi Godwin-Austen, 1915: 496, pl. 39, fig. 3, 3a. The type series of this species comprises lot "No. 3081 Brit. Mus." and two uncatalogued specimens in the Indian Museum. Without any explicit holotype designation or equivalent expression, all specimens are syntypes. However, only specimen lot "No. 3081 Brit. Mus." was mentioned in the "Type" paragraph, and one specimen from this lot was figured with the annotation "Type" in the plate caption. The author explicitly indicated that five specimens were examined, and type lot NHMUK 1903.7.1.3081 accordingly contains five specimens with a label in Godwin-Austen's handwriting stating "Type". We hereby designate the specimen from lot NHMUK 1903.7.1.3081 which is figured in the original description and in Sutcharit et al. (2019: fig. 10d) as the lectotype (NHMUK 1903.7.1.3081/1) to stabilize the name. This lectotype designation is based on the idea that Godwin-Austen (1915) selected this specimen lot as onomatophores.

Spiraculum kempi Godwin-Austen, 1915
Spiraculum kempi Godwin-Austen, 1915: 496, 497, pl. 39, figs 4, 4a, 5, 5a. The type series of this species comprises two specimen lots, "No. 3105 Brit. Mus." and "No. 3047 B.M.", and two uncatalogued specimens in the Indian Museum. Without any explicit holotype designation or equivalent expression, and given that the Register of Godwin-Austen Collection explicitly states that each lot contains two specimens (Fig. 7E, F), all specimens in these lots are syntypes. However, only the figured specimen from lot "No. 3105 Brit. Mus." from Abor Hills was marked as "Type" in the plate caption (Fig. 1B) and this lot is labelled as "Type" in Godwin-Austen's handwriting (Fig. 4A). In contrast, the figured specimen from lot "No. 3047 B.M." from Ponging was not marked as "Type" in the plate caption and this lot is labelled as "Typic" in Godwin-Austen's handwriting (Fig. 4B). Although, according to Art. 73.2., all the specimens of the type series are automatically syntypes and have equal status in being name-bearing types, we hereby designate the specimen from lot NHMUK 1903.7.1.3105 that is figured in Godwin-Austen (1915: pl. 39, fig. 4, 4a) and Sutcharit et al. (2019: fig. 7d) as the lectotype (NHMUK 1903.7.1.3105/1) to stabilize the name. This lectotype designation is based on the idea that Godwin-Austen (1915) selected this specimen lot as onomatophores and thus prevents any future attempt to designate a specimen from the other lots as the lectotype. The type locality of this taxon is restricted to "Abor Hills".

Spiraculum planum Godwin-Austen, 1915
Spiraculum planum Godwin-Austen, 1915: 497, pl. 39, fig. 6, 6a, Godwin-Austen (1915) regarded as a small variety. Without any explicit holotype designation or equivalent expression, all specimens in these lots are syntypes. However, only specimen lot "No. 5992 Ind. Mus." was mentioned in the "Type" paragraph, and one specimen from this lot was figured with the annotation "Type" in the plate caption. This specimen lot is, therefore, deemed onomatophore as originally intended by Godwin-Austen (1915). Therefore, subsequent authors should select that particular figured specimen from the lot NZSI M.5992 as the lectotype.

Pterocyclos aborensis Godwin-Austen, 1915
Pterocyclos aborensis Godwin-Austen, 1915: 498, pl. 39, fig. 1, 1a. Sutcharit et al. 2019 fig. 1b The type series of this species comprises three specimen lots. Without any explicit holotype designation or equivalent expression, all specimens in these lots are syntypes. However, only specimen lot "No. 3104 Brit. Mus." from Abor Hills was mentioned in the "Type" paragraph, one figured specimen from this lot was marked as "Type" in the plate caption, and this lot was labelled as "Type" in Godwin-Austen's handwriting (Fig. 5A). In contrast, two remaining lots, "No. 3046 B.M." from Ponging and "No. 3050 B.M." from Rami Lampang, were not labelled as type (Fig. 5B, C). Although, according to Art. 73.2., all the specimens of the type series are automatically syntypes and have equal status in being name-bearing type, we hereby designate the specimen from lot NHMUK 1903.7.1.3104 that is figured in the original description and in Sutcharit et al. (2019: fig. 1b) as the lectotype (NHMUK 1903.7.1.3104/1) to stabilize the name. This lectotype designation is based on the idea that Godwin-Austen (1915) selected this specimen lot as onomatophores and thus prevents any future attempt to designate a specimen from the other lots as the lectotype. The type locality of this taxon is restricted to "Abor Hills".
Godwin-Austen (1915) explicitly stated that four specimens of this taxon were obtained, the type specimen lot number was given as "No. 3580 Brit. Mus." and three specimens were transferred to the Indian Museum. However, currently there are four specimens in lot NHMUK 1903.7.1.3580, so it is presumed that none were sent to the NZSI. Without any explicit holotype designation or equivalent expression, these four specimens are syntypes. The specimen figured in the original description that corresponds to the shell measurements given is hereby designated as the lectotype (NHMUK 1903.7.1.3580/1; Fig. 8A) to stabilize the name.

Pterocyclos brahmakundensis Godwin-Austen, 1915
Pterocyclos brahmakundensis Godwin-Austen, 1915: 499, 500 Godwin-Austen (1915) explicitly stated that three specimens of this taxon were obtained, and the type specimen lot number was "No. 713 B.M." Without any explicit holotype designation or equivalent expression, these three specimens are syntypes. The specimen figured in Sutcharit et al. (2019: fig. 3d) that corresponds to the text figure and the shell measurements given in the original description is hereby designated as the lectotype (NHMUK 1903.7.1.713/1) to stabilize the name.
Only one specimen lot, "No. 3530 Brit. Mus.", was mentioned in the original description and associated with the "Type" paragraph. Although this type lot contains only one specimen and the Register of Godwin-Austen Collection reveals that there is only one specimen in this lot (Fig. 7G), it is nevertheless not evident in the original description that this taxon is based on a single specimen (ICZN 1999: Art. 73.1.2). Therefore, without any explicit holotype designation or equivalent expression, Sutcharit et al. (2019) validly deemed this specimen (NHMUK 1903.7.1.3530) as a syntype, following Recommendation 73F. We hereby designate this specimen, which is figured in the original description and also figured in Sutcharit et al. (2019: fig. 8d), as the lectotype (NHMUK 1903.7.1.3530/1) to stabilize the name.

Spiraculum minimum Godwin-Austen, 1915
Spiraculum minimum Godwin-Austen, 1915: 501, 502, pl. 40, fig. 2 The type series of this species comprises four specimen lots. Only two specimen lots, "No. 6142-43 Ind. Mus.", which were explicitly stated to contain two specimens from "Jeku, Abor Hills", were mentioned in the "Type" paragraph, and one of these two specimens was figured and marked as "Type" in the plate caption. In contrast, the remaining lots were mentioned in the body of the text of subsequent paragraphs. This could mean that Godwin-Austen (1915) selected specimen lots "No. 6142-43 Ind. Mus." as onomatophores. However, without any explicit holotype designation or equivalent expression, all specimens of the type series are automatically syntypes with equal status in being name-bearing types. Thus, the designation of the lectotype from lot NHMUK 1903.7.1.3145, labelled as "Typical" in Godwin-Austen's handwriting (Fig. 6C), by Sutcharit et al. (2019) is valid under the Code, although this action contradicted the intention of the onomatophore designation by Godwin-Austen (1915). The type locality of this taxon is restricted to "Sibbum, Abor Hills".
Godwin-Austen (1915) explicitly stated that two specimens of this taxon were obtained, with a type specimen lot number of "No. 3083 Brit. Mus.". Without any explicit holotype designation or equivalent expression, both specimens are syntypes. The specimen figured in the original description that corresponds to the shell measurements given is hereby designated as the lectotype (NHMUK 1903.7.1.3083/1; Fig. 8B) to stabilize the name.