﻿Revision of the “ Chloritisdelibrata (Benson, 1836)” group (Gastropoda, Stylommatophora, Camaenidae)

﻿Abstract Chloritisdelibrata (Benson, 1836), known from northeastern India, was believed to have three varietal forms, sometimes mentioned as subspecies: C.delibratavar.khasiensis (Nevill, 1877) and C.delibratavar.fasciata (Godwin-Austen, 1875) from the Khasi Hills, India, and C.delibratavar.procumbens (Gould, 1844) from Dawei in Myanmar. The reproductive anatomy of the latter form is known and does not match with those of any continental camaenid genera, but does with that of the newly examined Chloritisplatytropis Möllendorff, 1894 from Thailand. The latter species is conchologically similar to Bouchetcamaenahuberi Thach, 2018 (synonym of Helixfouresi Morlet, 1886), which is the type species of the genus Bouchetcamaena Thach, 2018. Thus, Bouchetcamaena can provisionally host the entire Chloritisdelibrata -group with the exception of var. fasciata, which is transferred to Burmochloritis Godwin-Austen, 1920 due to the multiple reddish bands on its shell. The examination of shells deposited in the Natural History Museum, London revealed that seven morphologically distinguishable forms are present, which are accepted here as representing distinct species. Four new species are described from India: Bouchetcamaenafoveata Páll-Gergely sp. nov., B.fusca Páll-Gergely sp. nov., B.raripila Páll-Gergely sp. nov., and B.subdelibrata Páll-Gergely sp. nov.


Introduction
Chloritis (Trichochloritis) delibrata (Benson, 1836) was considered to be a variable camaenid species inhabiting a relatively large area from Assam in India to Dawei (= Tavoy) in Myanmar (Stoliczka 1871;Gude 1914). The distance between these two sites is approximately 1500 km as the crow flies. The last overview of this species was published over a century ago in the Fauna of British India by Gude (1914) who listed three varieties: var. khasiensis (Nevill, 1877) and var. fasciata (Godwin-Austen, 1875) from the Khasi Hills, India, and var. procumbens (Gould, 1844) from Tavoy, Myanmar. The two Indian varieties were listed as subspecies of Chloritis delibrata in the latest Indian checklist (Ramakrishna et al. 2010).
Examination of specimens assigned to Chloritis delibrata and its forms in the Natural History Museum, London, revealed that at least seven species can be distinguished based on the shape the shell and, most importantly, its fine sculpture. Thus, we here give an overview of the C. delibrata group, and describe the morphologically recognisable, distinct entities as species.

Generic position
Placing the Chloritis delibrata-group in its appropriate genus turned out to be challenging. The morphology of the jaw and the radular teeth, along with the outer characters of the reproductive anatomy of "var. procumbens" from Moulmein were described by Stoliczka (1871) [redrawn by Pilsbry (1894) and in this manuscript ( Fig. 1)]. Based on these descriptions, the penis is spindle-shaped, the epiphallus is longer than the penis, slender, cylindrical, the retractor muscle inserts at the penisepiphallus transition, and there is a slender, pointed, moderately short flagellum. We needed to examine the possible placement of the Chloritis delibrata-group in Chloritis Beck, 1837, Trichochloritis Pilsbry, 1891, and Trachia Martens, 1860, since this species complex had previously been placed in those genera, along with Bellatrachia Schileyko, 2018, Bouchetcamaena Thach, 2018, Burmochloritis Godwin-Austen, 1920, Neotrachia Schileyko, 2018, Planispira Beck, 1837, Satsuma A. Adams, 1868, and Sinochloritis M. Wu & Z. Chen, 2019, which inhabit the same or adjacent geographic areas. The key traits of the reproductive anatomy are summarized in Table 1.
The anatomy of the type species of Trichochloritis (Helix breviseta Pfeiffer, 1862) is known based on Stoliczka (1873) (see also Páll-Gergely and Neubert 2019). The most obvious difference is the presence of a slender but relatively long penial caecum, which is absent in C. delibrata var. procumbens. Further differences include the following: flagellum shorter, vagina longer in Trichochloritis, and bursa of bursa copulatrix more ovoid, less elongated.
Some species of Satsuma (type species: Helix japonica L. Pfeiffer, 1847;SD, Kuroda and Habe 1949) from China are similar to the delibrata-group in terms of the thin shell with a single band, but Satsuma is characterized by a well-developed penial caecum (Wang et al. 2014;Zhang et al. 2019). We note that those Chinese Satsuma species possess a short, vestigial flagellum, which is well developed, rather long in the type species of Satsuma (see Emura 1933;Azuma 1995;unpublished information); thus, the generic status of the Chinese Satsuma species requires a revision.
Sinochloritis, known only from the Chinese Sichuan Province, also possesses a large penial caecum. Thus, we do not consider the C. delibrata-group to belong to any of those three genera (Trichochloritis, Satsuma, Sinochloritis).
The type species of Trachia Martens, 1860 (Helix asperella L. Pfeiffer, 1846) is not known anatomically. The anatomy of Trachia vittata (O. F. Müller, 1774) was  (Gould, 1844). Redrawn from Stoliczka (1871).  Schileyko (2003), who revealed that it is entirely different from that of Chloritis delibrata, since the retractor muscle joins the fibrous sheath around the penis. Later, Schileyko (2018) claimed that since the shell of Trachia asperella is similar to that of "Helix" delibrata, their anatomy is also probably similar, and thus, classified C. delibrata in Trachia. However, Trachia vittata possesses multiple spiral bands, whereas only a single band is present in the delibrata-group. More importantly, Trachia vittata is known from central and southern India (Gude 1904;Mitra et al. 2004), whereas the delibrata-group is restricted to the areas southeast of the Himalaya, a biogeographically very distinct region. Moreover, most other species named by Schileyko (2018) as possible Trachia species also inhabit the Indian subcontinent.
Thus, it is improbable that Trachia vittata and the species of the C. delibrata-group would belong to the same genus.
Bellatrachia differs from Stoliczka's (1871) drawing of C. delibrata var. procumbens by the much longer penis and epiphallus, the well-developed flagellum, and the thickened base of the bursa copulatrix.
The genital anatomy of Neotrachia is very different from that of C. delibrata var. procumbens due to its short penis and swollen epiphallus (Schileyko 2018).
The type species of Planispira Beck, 1837 (Helix zonaria Linnaeus, 1767) was redescribed by Schileyko (2003) as having penis swollen and epiphallus relatively short and thick (spindle-shaped penis and long, slender epiphallus in C. delibrata), and stalk or bursa copulatrix very long, convoluted.
This makes it improbable that the C. delibrata-group belongs to any of the genera Bellatrachia, Burmochloritis, Neotrachia, and Planispira.
The type species of the genus Chloritis is Helix ungulina Linnaeus, 1758 (SD, Gray 1847), which was described without stating the type locality. Subsequently it turned out to inhabit Indonesia (Zilch 1966). Although the anatomy of Chloritis ungulina is unknown, it is highly unlikely that the Chloritis delibrata-group would belong to the same genus due to the geographical separation of the two species. Some continental (Thailand, Vietnam) species are classified in Chloritis, and their genitalia largely agree with Stoliczka's drawing (Sutcharit and Panha 2010;Páll-Gergely and Neubert 2019;Páll-Gergely et al. 2020). However, the presence of a penial caecum distinguishes continental Chloritis from Bouchetcamaena (see below).
We examined the reproductive anatomy of a specimen of Chloritis platytropis Möllendorff, 1894 from Thailand (Figs 2A,3,4), which is conchologically similar to the type species of Bouchetcamaena Thach, 2018(Bouchetcamaena huberi Thach, 2018: synonym of Helix fouresi Morlet, 1886). Consequently, the anatomy of Chloritis platytropis can be used to characterize Bouchetcamaena. Chloritis platytropis differs from the C. delibrata-group only in the keeled shell, whereas their reproductive anatomy is similar. Moreover, Chloritis gabata (Gould, 1844) (Fig. 5B), which was described from Dawei, Myanmar (the type locality of Chloritis delibrata var. procumbens), is similar to the type species of Bouchetcamaena in shell shape, size and sculpture (including the prominent keel), and differs from the C. delibrata-group only in the presence of a keel on the body whorl. We here move Chloritis gabata (Gould, 1844) and Chloritis platytropis to the genus Bouchetcamaena, comb. nov.
Thus, Bouchetcamaena can host the entire Chloritis delibrata-group with the exception of var. fasciata, which is transferred to Burmochloritis Godwin-Austen, 1920, comb. nov. due to the multiple narrow spiral bands on its shell. The anatomical characters are summarized in Table 1.

Materials and methods
Determination of the number of shell whorls (precision to 0.25 whorl) follows Kerney and Cameron (1979: p. 13). In the case of close-up images, multilayer close-up photographs were taken of each shell.
Locality data presented with the specimen examined data are cited as verbatim from the specimen labels. For Indian and Burmese localities see Páll-Gergely et al. (2015a, 2015b. Measurements were taken on the visually selected largest and smallest    specimens. Figure 6 presents the exact position of shell details that have to be checked when identifying species of Bouchetcamaena. Diagnosis. The shell characters are similar to those of most other Chloritis-like groups. Shell depressed to depressed globular (sometimes with a sunken apex), body whorl rounded, colour uniform with a single peripheral band, shell surface covered by hair scars (pits) of variable density (in some cases these are more or less absent on the last whorl) and deciduous periostracum of variable thickness, aperture rounded to oval/subrectangular, peristome expanded, parietal callus only indicated, umbilicus relatively narrow (narrower than one fourth of the shell's width). The genital organs [based on B. procumbens (Stoliczka 1871) and B. platytropis (this study)] are characterized by an elongated penis (spindle-shaped or with slightly swollen proximal end), the absence of a penial verge, a slender, cylindrical epiphallus longer than the penis, a retractor muscle inserted at the penis-epiphallus transition or on the distal end of the epiphallus, and a slender, pointed, elongated flagellum.

BSNH
Remarks. We only move the few species revised here to this genus. However, several other camaenid species from Southeast Asia may belong to Bouchetcamaena, which will be revealed by future studies.   Hills, coll. Godwin-Austen, no. 183, NHMUK 1903.7 Diagnosis. Shell large, flat, olive green, glossy, last whorl practically without hair scars, or widely-spaced hair scars near the parietal callus, aperture oval.
Description. Shell relatively large, rather thin-walled; depressed, dorsal side usually entirely flat, rarely very slightly elevated; colour greenish-olive to greenish-yellowish with an obscure, reddish band just above the blunt keel (rarely missing); protoconch consists of 1.75 whorls, with very fine radial ribs and regularly arranged hair scars (pits); entire shell with 4 whorls; separated by a moderately deep suture; teleoconch overall glossy, with irregular, fine growth lines, dorsal side of first 2.0-2.5 whorls covered by widely-spaced hair scars (= pits), and short hairs near suture; ventral side of body whorl without hair scars or widely spaced (in some specimens somewhat denser than in others) pits near the parietal callus only; aperture oval/subrectangular; peristome strongly expanded and slightly reflected in direction of umbilicus; palatal part with very thin, whitish, semi-transparent layer, showing hair scars on penultimate whorl; umbilicus open, relatively wide, funnel-shaped, peri-umbilical keel only very slightly indicated.
Measurements   Diagnosis. Shell relatively large, fragile, thin-walled, dorsal side flat or even slightly sunken, colour light yellow to whitish, with a faint peripheral band; hair scars represented as elevated knobs (like strawberry seeds), or even hair scars represented as truncated hairs or short, slender, pointed hairs; aperture oval, umbilicus relatively narrow.
Description. Shell medium-sized to large, thin-walled; dorsal side flat or even sunken; basic colour light yellowish to whitish, a peripheral band of various thickness present in all specimens, running around the shoulder or the body whorl; protoconch consisting of 1.50-1.75 whorls, finely wrinkled and covered by widely-spaced hair scars reminiscent of strawberry seeds; entire shell consisting of slightly less or more than 3.75-4 whorls, separated by a relatively deep suture; teleoconch very finely and irregularly wrinkled; hair scars (reminiscent of strawberry seeds) widely-spaced, clearly visible on the entire teleoconch; occasionally (near suture, behind expanded peristome, inside umbilicus, etc.) short, slender, pointed hairs remaining; hairs inside umbilicus denser than elsewhere on the teleoconch; aperture oval/subrectangular; peristome strongly expanded and slightly reflected, especially in direction of umbilicus; palatal part with thin, whitish, semi-transparent layer, which allows hair scars of penultimate whorl to be seen; umbilicus open, normally wide, funnel-shaped, peri-umbilical keel blunt.
Measurements. D = 20.3-20.5 mm, H = 9.1-10.5 mm (n = 3). Differential diagnosis. This new species differs from that which is the most similar, B. delibrata, in having a flatter dorsal side, glossier shell, and deep hair scars on the entire surface. The hair scars of B. subdelibrata sp. nov. are much finer and denser on the entire shell surface.
Etymology. The new species is named after its conspicuously pitted (= foveatus in Latin) surface.
Distribution. All samples with relatively precise localities were collected in the Khasi Hills.
Description. Shell small to medium-sized; depressed-globular, dorsal side flat or spire very slightly elevated; body whorl slightly or relatively strongly but bluntly shouldered; colour brownish due to thick, matt periostracum; protoconch consists of 1.5 whorls, finely wrinkled, with short hairs near suture; in some specimens wrinkles only visible in the middle of whorls, whereas in others hair scars (pits) are also discernible; entire shell consisting of 3.75-4 whorls, suture moderately deep; short hairs visible in the suture and inside umbilicus; hair scars practically invisible due to thick periostracum; in one paratype (NHMUK 1903.7.1.391) periostracum of lighter colour around each hair scar on the ventral side, making the density of scars visible; very few hair scars visible at the parietal callus, but to a much lesser degree than in other species; aperture oval/subrectangular; peristome expanded and slightly reflected in direction of umbilicus; palatal part with a very thin, whitish, semi-transparent layer; hair scars not visible beneath parietal callus; umbilicus open, relatively narrow, peri-umbilical keel only very slightly indicated.
Measurements. D = 15.3-18.7 mm, H = 7.8-8.8 mm (n = 5). Differential diagnosis. Bouchetcamaena raripila sp. nov. is most similar to B. fusca sp. nov. in having a relatively small shell, narrow umbilicus and brown periostracum, but it differs in the strong, sparsely standing hair scars. All other Bouchetcamaena species have larger, lighter-coloured shells and a wider umbilicus.
Etymology. The new species is named after its dark (fuscus in Latin) periostracum. Distribution. Seems to be restricted to Manipur, the Khasi and the Naga Hills (India).  fig. 9) as var. khasiensis, and mentioned that it has more raised and rounded whorls and a less open umbilicus than the typical H. delibrata. Nevill's (1877) description was as follows: "The raised and rounded whorls, less open umbilicus, and contracted aperture will distinguish the form; it has sometimes a single brown band, but is often without it; it is tolerably abundant in the Naga and Khasi Hills. (...) Var. khasiensis, from Khasi Hills, axis 8.5, diam. 19.5 (apert. 9, diam 10.5) mm".
Description. Shell medium-sized, rather thin-walled; dorsal side flat, very rarely (NHMUK 1906.2.2.121) slightly domed; shell shape "nautiliform" (i.e., initial whorls  closely coiled, body whorl conspicuously expanded); colour whitish to light yellowish with somewhat darker yellowish, matt (dull) periostracum in some places, or, as in one sample (Mutan, Tenasserim), on the entire shell; a normally wide, faint reddish-brown belt running around the shoulder of the body whorl (can be entirely absent); protoconch consisting of 1-1.5 whorls, finely wrinkled and covered by hair scars (pits) or small, mamilla-like hairs; entire shell consisting of 3.75-4.75 whorls, separated by a deep su-ture; teleoconch finely and irregularly wrinkled; sculpture variable: in typical shells some darker yellowish-light brownish periostracum covers parts of the teleoconch, and the densely arranged hair scars are only visible in the suture on the dorsal side and near the parietal callus on the ventral side; in the "pitted form", hair scars densely arranged on entire shell and clearly visible on both the dorsal and ventral sides; aperture oval/subrec- tangular; peristome strongly expanded and slightly reflected in direction of umbilicus; palatal part with a thin, whitish, semi-transparent layer, with hair scars visible on penultimate whorl; umbilicus open, narrow, funnel-shaped, peri-umbilical keel blunt.
Measurements. D = 15.8-19.5 mm, H = 7.8-9.4 mm (n = 7). Differential diagnosis. The smaller shell size and the more reflected peristome distinguish this species from the most similar species, B. delibrata. Furthermore, the "white type" B. procumbens differs from B. delibrata in the presence of dense and prominent hair scars.
Distribution. Seems to be restricted to southern Myanmar. Remarks. Johnson (1964) mentioned that the figured "holotype" (MCZ 169311) is from the NYSM 232 (original no. A 567), and that there is a "paratype" (USNM 611226) from the same NYSM lot. Johnson's listing of the specimen as a "holotype" has to be accepted as an indirect lectotype designation by inference of holotype (see ICZN Art. 74.6). Furthermore, two additional "paratypes" (= paralectotypes) are found in the MCZ (reg. no.: 87935,ex BSNH).
There are two forms of this species. One is lighter in colour, some of the specimens have a slightly sunken spire and possess uniformly arranged, strong hair scars on the entire surface of the shell ("white type"), whereas the other type has a darker shell (yellowish to light brownish) with hardly visible hair scars ("darker type"). The sample NHMUK 1906.2.2.121 contains four shells of identical appearance; however, one of them has widely-spaced pits, whereas the other three have only some pits on the callus area but otherwise no hair scars. Thus, it seems that the strength of the hair scars is variable within this species, unlike in all other species of this group. Since the shell and aperture shape are, with the exception of spire height, practically identical, and there are transitional forms between the two types in terms of shell sculpture, we provisionally treat them as one species. There are no clearly visible hair scars on the lectotype. Thus, the form without prominent hair scars is considered typical procumbens, and the "pitted form" is considered atypical.
Diagnosis. Shell small, with slightly elevated spire; periostracum thick, brown, hair scars (truncated hairs or strawberry seed-like scars) extremely sparsely arranged on the body whorl; aperture oval, almost rounded.
Description. Shell small; depressed-globular, with very slightly elevated spire (low domed dorsal side); body whorl rounded; colour brown due to thick, matt (dull) periostracum, locally worn locally making the nude whitish shell surface visible; protoconch consists of 1.5 whorls, finely wrinkled, with hair scars reminiscent of strawberry seeds; entire shell consisting of 4.25 whorls, suture moderately deep; inside of umbilicus and suture with mamilla-like, relatively densely arranged hair scars; other parts of teleoconch with extremely widely-spaced hairs (truncated, reddish-brown hairs or strawberry seedlike scars, and very few, relatively long, conical hairs); aperture oval, almost rounded; peristome strongly expanded and slightly reflected in direction of umbilicus; palatal part with a very thin, whitish, semi-transparent layer, which allows hair scars of the penultimate whorl to be seen; umbilicus open, narrow, funnel-shaped, peri-umbilical keel blunt.
Measurements. D = 15.4 mm, H = 8.1 mm (n = 1). Differential diagnosis. Differs from B. procumbens by having a more rounded shell shape and the last whorl is also more rounded. Most important are the extremely widely-spaced and prominent hair scars. This latter trait distinguishes B. raripila sp. nov. from all other similar species.
Etymology. The name raripila refers to the few hairs/hair scars on the shell surface (rarus: few, pilus: hair in Latin).
Distribution. The new species is known from the type locality only. Kopanedza (also spelled Kopamedza) is situated in the Barail Range, Dafla Hills (India), although its exact locality is unknown (Páll-Gergely et al. 2015b Additional material examined. Same data as holotype, NHMUK 20191132/3 (7 juvenile shells).
Description. Shell medium-sized, rather thin walled; depressed, dorsal side entirely flat (type series), or slightly elevated (Habiang); colour greenish to dark yellowish with an obscure, reddish band just above the blunt keel; protoconch consisting of 1.5 whorls, with densely arranged, clearly visible, knob-like hair scars; entire shell with 3.50-3.75 whorls; separated by a rather deep suture; teleoconch overall glossy, with irregular, fine growth lines, ventral side and edge of body whorl (except for last quarter whorl) covered with densely-arranged hair scars, some hair scars also recognizable on the last quarter whorl, but not regular as on the preceding areas; last whorl of dorsal side dominated by wrinkles, and regular hair scars only visible in areas before the last half whorl; aperture almost rounded, slightly oval; peristome strongly expanded and slightly reflected in direction of umbilicus; palatal part with a very thin, whitish, semi-transparent layer, which allows hair scars on penultimate whorl to be seen; umbilicus open, normally wide, funnel-shaped, peri-umbilical keel blunt, only very slightly indicated.
Measurements. D = 17.7-19.3 mm, H = 8.6-9.9 mm (n = 4). Differential diagnosis. Bouchetcamaena delibrata is most similar to the new species, but it is larger, has a more strongly depressed shell, elongated aperture and expanded peristome, and lacks hair scars on the last half whorl. The hair scars of B. delibrata are more widely-spaced than those of B. subdelibrata sp. nov. Etymology. The specific epithet refers to the most similar species. Distribution. The new species is known from the Garo Hills (Meghalaya, India), and the neighbouring Silhet Hills to the south.
Remarks. Burmochloritis Godwin-Austen, 1920 possesses a long flagellum, has penial caecum well-developed, and a large, additional organ originating from the wall of the vagina (Godwin-Austen 1920; and unpublished information). See also Table 1.
Description. Shell medium-sized, rather thick-walled; depressed globular, with slightly domed dorsal side; colour greenish-yellowish, with a main but still slender reddish band just above the blunt keel and several even thinner belts on both the dorsal and ventral surfaces; protoconch consists of 1.25 whorls, with very fine radial ribs and regularly arranged hair scars; entire shell consists of slightly more than 4 whorls, separated by a moderately deep suture; teleoconch covered with a matt periostracum, dense hair scars (and short hairs near suture) visible only near parietal callus; aperture rounded/subrectangular; peristome strongly expanded and slightly reflected in direction of umbilicus; parietal part with thin, whitish, semi-transparent layer, which allows hair scars of penultimate whorl to be seen; umbilicus open, relatively narrow, funnel-shaped, with blunt peri-umbilical keel.
Remarks. This species was described as a variety of B. delibrata, but differs in numerous shell characters (smaller, more globular shell, smaller protoconch, domed dorsal side, comparatively smaller, more rounded aperture, narrower umbilicus, denser hair scars). Thus, it should be handled as a species in its own right. Moreover, based on the multiple spiral bands (Bouchetcamaena species have no band or a single band), this species is transferred to the genus Burmochloritis, although this placement requires confirmation through anatomical examination.