The Diplommatinidae of Fiji – a hotspot of Pacific land snail biodiversity (Caenogastropoda, Cyclophoroidea)

Abstract The minute (adult size 1.3–4.8 mm) land snail species of the family Diplommatinidae in the Fiji archipelago are revised based on historical material and modern (1998–99) collections targeting limestone outcrops on the largest island, Viti Levu, and several smaller islands in the Lau group. The forty-two species (including 30 new species) belong to the genera Moussonia Semper, 1865, Palaina Semper, 1865 and Diancta Martens, 1867, which are briefly characterized and keyed. The diagnostic structure of the inner lamellar system of each species is illustrated. All species except one are endemic to Fiji. In Viti Levu, the 12 localities surveyed each had 1–13 (average 5) species of Diplommatinidae; ten species were each found at a single site only. In the Lau islands, five islands were visited, with 1–4 species per island; four species are known from single islands. The number of historically known species not recollected in 1998–99 (7 species), the number of single-site occurrences (14 species), and the numerous islands — including limestone islands — that have not been surveyed at all, indicate that the 42 species of Diplommatinidae currently known from Fiji represent perhaps only half of the Fiji diplommatinid fauna. Such numbers approach the diplommatinid diversity of Palau (39 described and more than 60 undescribed species), and surpasses by far the diversity of other South Pacific archipelagos of comparable land area (New Caledonia, Vanuatu, Samoa). Nomenclatural acts: Lectotypes designated: Diplommatina fuscula, Diplommatina fuscula var. vitiana, Diplommatina godeffroyana, Diplommatina godeffroyana var. latecostata, Diplommatina tuberosa, Diplommatina martensi var. macrostoma, all Mousson, 1870. Neotypes designated: Diplommatina subregularis, Diplommatina ascendens, Diplommatina quadrata, all Mousson, 1870. New species: Diancta aurea sp. n., Diancta aurita sp. n., Diancta basiplana sp. n., Diancta controversa sp. n., Diancta densecostulata sp. n., Diancta dextra sp. n., Diancta dilatata sp. n., Diancta distorta sp. n., Diancta pulchella sp. n., Diancta rotunda sp. n., Diancta subquadrata sp. n., Diancta trilamellata sp. n., Moussonia acuta sp. n., Moussonia barkeri sp. n., Moussonia brodieae sp. n., Moussonia longipalatalis sp. n., Moussonia minutissima sp. n., Moussonia obesa sp. n., Moussonia polita sp. n., Moussonia uncinata sp. n., Moussonia vitianoides sp. n., Palaina alberti sp. n., Palaina flammulata sp. n., Palaina glabella sp. n., Palaina kitteli sp. n., Palaina labeosa sp. n., Palaina parietalis sp. n., Palaina sulcata sp. n., Palaina truncata sp. n., Palaina tuberosissima sp. n.


Introduction
For many of the Pacific islands, Captain Cook's voyages are the starting point of European scientific discovery of the local faunas and floras. However, although Cook stopped in Fiji in 1774, no land snails were collected or described from Fiji as a result of his voyages. In fact, the first land snail from Fiji was not described until 1834, quite a late date compared to the first discovery of land snails from New Zealand, New Caledonia or the Solomons, but a date comparable to the first discovery of the land snails of Tonga, Samoa, and the Society Islands. This may be a result of the land snails of the Pacific archipelagos from Fiji eastward being not very spectacular and thus escaping the attention of the untrained navy officers who were collecting all sorts of natural history items. The diplommatinids that form the focus of this paper are indeed small to minute, with adult sizes of 1.3-4.8 mm, the majority of species 2-3 mm. Until now, 12 species were known from Fiji, nearly all described by Zürich-based conchologist Albert Mousson, based on material collected by Eduard Graeffe, a young naturalist sent to explore Samoa, Uvea [= Wallis], Tonga and Fiji by the enlightened Hamburg merchant Cesar Godeffroy (see Bieler and Petit 2012). The two resulting contributions by Mousson (1865Mousson ( , 1870 constitute the foundation of Fiji malacology and contain the descriptions of approximately one-third of the Fiji land snail species today recognized as valid, among them Diplommatina godeffroyana [now Palaina godeffroyana]. The Godeffroy Museum, later incorporated in the Hamburg University Museum, was destroyed during the bombing of Hamburg at the end of World War II. However, the amount of material collected by Graeffe must originally have been enormous, and scattered lots survive in many European and North American museums, notably Zürich (which has the Mousson collection) and Paris (which has the specimens illustrated in Mousson's papers). Immediately after Graeffe, the Tahiti-based American conchologist Andrew Garrett started a two-years long exploration of the Fiji land snail fauna. Garrett's work was remarkable for his numerous observations on the habitats and ecology of the species but, although he visited many then malacologically unexplored islands, he surprisingly did not add a single species to the inventory of Fiji diplommatinids (Garrett 1887). In fact, after Mousson, a single new species of diplommatinid was added to the Fiji list (Liardet 1876) and nothing else for the following 140 years. Despite easier access by road to the mountain areas or by air to many islands, it is ironic that, besides Gary Barker's still unpublished efforts (G. Barker, pers. com.), very little scientific collecting has taken place in Fiji in recent decades. The Fiji species were last reviewed by Kobelt (1902) and their systematics are in great need of revision. Several species were never illustrated, and some of the forms initially described as "varieties" in fact represent distinct species. Currently, ten species are recorded from Viti Levu, two from Ovalau and the Lau islands, and a single species from Taveuni. Of the 12 named taxa recorded from the Fiji archipelago, all but one are endemic.
The species of Diplommatinidae live in the leaf litter and can be extremely abundant -and diverse -in limestone regions. Twenty days of field work in 1998 and 1999 that sampled also spring snails (Haase et al. 2007) generated no less than 8,547 specimens of Diplommatinidae, representing 35 species. Segregating the Fiji diplommatinid fauna into species is relatively straightforward, but placing them in genera is problematic.
After being relegated for decades in the backwater of land snails systematics, the Diplommatinidae have recently hit the front line of molecular data, integrative taxonomy, and even cybertaxonomy. At the generic level, Webster et al. (2012) reconstructed a 5-genes molecular phylogeny of 71 specimens of Diplommatinidae from SE Asia and the West Pacific, representing 54 recognized species and 7 putative genera. Their results indicate that (1) monophyletic clades correspond with both coiling direction and biogeographic patterns; and (2) the ancestral state in the family is sinistrality, with several shifts (three in their dataset) to dextrality. At the species level, Tillier (1981) monographed the New Caledonia fauna. Based on anatomical characters, he concluded that species vary considerably in both shell size and shape, and that "in many cases the species can be distinguished only by their anatomy". According to Tillier, "species exhibit clinal variation in shell characters that are related to environmental conditions". Tillier's unconventional approach to diplommatinid taxonomy has not been repeated elsewhere, and obviously would be worth revisiting with molecular data. An integrative approach was followed by Yamazaki et al. (2013) who used shell, radula and molecular characters to revise the genus-and species-level systematics of the family Diplommatinidae in Palau. The "cybertaxonomy" approach of Liew et al (2014), based on 3D models and COI sequences, reviewed the species of Plectostoma H. Adams, 1865 from southeast Asia and treated 31 species (including 10 new species descriptions). Meanwhile, numerous other papers are still classically defining species based on shell characters only (e.g., Stanisic et al. 2010, Tongkerd et al. 2013, Simone 2013. Vermeulen (1993) and Stanisic et al. (2010) used the genus name Diplommatina Benson, 1849 in a very broad sense for an enormous number of species delimited solely by shell characters. However, Yamazaki et al. (2013) advised against the broad use of Diplommatina. With the few exceptions reviewed above, modern concepts of the numerous genera of Diplommatinidae are still lacking. Irrespective of chirality, the Diplommatinidae of Fiji fall into three larger groups, based on shell characters, which here are considered to constitute genera (see discussion under the respective genus headings). The lesson from Webster et al. (2012) is that genera tend to be constrained to discrete geographical areas, and we have been guided by this conclusion in allocat-ing the Fiji species to genera. Four nominal genera have their type species from islands in the South Pacific: Moussonia Semper, 1865 (Samoa), Palaina Semper, 1865 (Lord Howe Island), Macropalaina Möllendorff, 1897 (Fiji) and Palmatina Iredale, 1944 (Norfolk Island). The names Moussonia and Palaina (including Macropalaina, see below) are easily applicable to the Fiji fauna. For the third Fiji shell group, we have used Diancta Martens, 1864 (type species from the Moluccas). These working hypotheses will have to be validated in a broader geographical context and with anatomical and molecular characters, a goal far beyond that of the present paper.

Material and methods
During two visits to Fiji by the second author (August 1998, andMarch 1999), the limestone outcrops of Viti Levu were specifically targeted, and opportunities to sample several of the lesser known and more remote islands in the Lau group arose during the BORDAU 1 oceanographic expedition (Richer de Forges et al. 2000). Standard methods for collecting microsnails in leaf litter were used, including a Winkler sieve, and rock faces and shrubs were inspected visually for rupicole and arboreal species. The dried leaf litter residues were sorted by Klaus Kittel, who immediately recognized that the magnitude of the Fiji diplommatinid radiation was considerably higher than had been recorded in the literature.
Diplommatinidae have a rich character set of the internal lamellae apparatus that can be used for species distinction. Names of the internal lamellae are here used in the sense of Vermeulen (1993), but a few additional terms have been created to accommodate the sometimes quite peculiar formation of some of these lamellae. The following definitions are used ( Fig. 1): columellaris: a single lamella running on the columella into the interior of the shell; it may be visible as a basal columellar denticle in the aperture, it can have an interior undulation and secondary denticles on top of the lamella. columellar plate: a basal broadening of the columella in the last whorl; it may be subdivided into two sections, the outer plate (pointing towards the aperture), and the internal plate (pointing towards the interior of the shell). parietal structures: these may be either parietal denticles (i.e. single cone-like teeth visible in the aperture), or internal lamellae on the roof of the ultimate to penultimate whorls. In cases in which there are two parietal lamellae, the first (counted from the aperture) is usually a long lamella, the second very often a broad, spatulate lamella, which often runs at an angle to the first one. palatal structures: there can be one to several lamella or small denticles, which may have either a spiral or axial orientation (i.e. perpendicular to the shell's axis); in constricted species, they may tend to be shifted also to the base of the penultimate whorl. constriction: in certain species, the penultimate whorl suddenly decreases in diameter, with the last whorl continuing with the same growth increment as the whorls before the constriction (and thus is consequently much larger than the constricted whorl). Vermeulen (1993: 6) used the name "tuba" for the post-constriction whorls, because in some diplommatinid genera this part detaches from the shell forming an irregular tube. This is not the case in any of the diplommatinid species from Fiji, and thus the term "tuba" is not used here. bulb: a lateral voluminous protrusion of the ultimate whorl. bulb lamella: an axial lamella inside the bulb that reinforces the shell at this particular place.
The lamellar system is usually placed ca. 0.5-1.5 whorls inside the shell, so many of these structures are placed in the whorl above the aperture, or even deeper inside the shell. The amount of constriction corresponds to the diameter of the operculum. While resting or as a reaction to other threats, the animal withdraws deeply behind the constriction, and has to pass all lamellae and teeth.
Preparation of shells showing the internal lamellar system requires some practice; the best way is to fix a specimen between two fingers, and use an insect needle (size 0) to break the dorsal wall of the shell through the aperture. After that, the shell fragment can quite easily be removed. At first glance, species may look very much alike, and in order to provide an overview and fast recognition of the species, a character matrix is provided (Table 1).
Size indications are relative to the size range of the species within the genera. In an absolute sense, a large species of Moussonia thus compares to small Palaina or Diancta species. In species with a double peristome, measurements of the aperture are from the inner peristomial lip.  Table 1. Character state matrix: 1 = present, 0 = absent. -Abbreviations used: bla = bulb lamella; bul = bulb; con = constriction; cpl = columella formed as a plate (with various states of reduction) (1) or as a lamella (2); oc = operculum thickened concentric; os = operculum simple; pal = number of palatal lamellae; prt = number of parietal lamellae; rp = ribbing pattern, with (1) = widely spaced throughout the whole shell, (2) densely spaced throughout the whole shell, (3) ribbing pattern changing in different parts of the shell.
Taxon//character bla bul con cpl oc os pal prt rp We have tried to document the opercula of all species but not all species were collected alive and some opercula are thus not known. Usually, the opercula of Diplommatinidae are inadequatetly described (if at all) in the literature, probably because they are considered to be quite simple and uniform and of no taxonomic use. In fact, it is usually a flat, circular corneous plate, which internally may show a small lamella (here called apophysis). It is not fully clear whether the apophysis functions as the place where a kind of retraction muscle adheres, or whether the whole internal area is attached to the operculum-generating tissue and muscle. Our observations show that there obviously is some variation in the construction of opercula. Next to the simple form with the outer and inner surface being flat, opercula may have a structured outer surface with tightly arranged concentric periostracal lamellae. Often, these structures are not easily visible, because they are obscured by soil particles that are quite firmly fixed to them. It is not clear whether these structures are actively used by the animals as a surface to which such particles can be glued, or whether this is passive contamination that is stable simply because of the rough surface of this type of operculum. It must be stressed that this type of operculum occurs exclusively within the group we have identified here as genus Palaina.
Specimens are housed in MNHN unless otherwise stated, some are in NMBE; a reference collection will be deposited at the University of the South Pacific, Suva. All photos were taken with Leica DFC 425 multi-layered photography system. All measurements are in mm. The number following the slash after a catalogue number indicates the number of specimens in the lot. All localities are geo-referenced, the coordinates are supplied as decimal numbers; collecting dates are given as day.month.year.

Diagnosis.
Shell dextral or sinistral, constriction easily visible to reduced, umbilicus always closed; protoconch usually with a pitted microsculpture; aperture shifted right or left of shell axis; no pleats visible in the aperture, columella reinforced by 1-2 plates situated right or left of the columella, often with a palatal callosity in opposition, parietalis can be present, often reduced; operculum corneous, multispiral, flat, with an elongate internal apophysis. Remark. Martens (1864: 119) defined the genus Diancta by "penultimate whorl with a constriction". Quadras and Möllendorff (1895) added the new subgenus Paradiancta (type species Diancta philippinica Quadras & Möllendorff, 1895, from the Philippines), which is characterised by dextral shells with a long palatalis and columellaris. Kobelt (1902: 419) added to the general definition that the shell of Diancta is oval and somewhat irregularly coiled. This short summary shows that the definition of these genera is based on taxonomically unimportant shell characters. Constriction of the shell is not an autapomorphic but a plesiomorphic character; for example, it is found in other genera like Opisthostoma Blanford, 1860(Vermeulen 1991 and Diplommatina Benson, 1849(Vermeulen 1993, 1996. The diplommatinid species of Lord Howe Island were also placed in Diancta by Stanisic et al. (2010). The shells of these species show some resemblance to those from Fiji, and may be closely related to the Fiji radiation. An analysis of the inner lamellar system of these species would be desirable. Description. Shell sinistral, elongate oval, yellowish; last whorl constricted; protoconch broad, obtuse, with a fine pattern of granules; umbilicus closed, concave narrow periomphalum; teleoconch sculpture of coarse widely spaced ribs, ribbing pattern constant throughout the shell, somewhat denser on the dorsal side of penultimate whorl; aperture broadly subquadrate, peristome doubled, with the upper left edge slightly protruding; apertural rims connected by a thin, slightly detaching callus; aperture only just attached to the last whorl; no pleats visible in the aperture; inside the shell, two small columellar plates present.
Operculum corneous, flat, internally with a small lamella.  Mousson's handwriting) were examined. It is clear that Mousson intended to separate these specimens under the name "distorta", but this remained a manuscript name. In fact, both lots contain typical specimens of D. martensi. It is not clear why Solem used "Diplommatina distorta Mousson", nor why he considered the two taxa as distinct. We here identify the modern lots recorded above with this species. Although on average, specimens from these lots are somewhat smaller than the possible syntype, no other character justifies their separation. the original description (see below). Because of the need to unambiguously stabilize the taxonomic extension of this nominal species, this specimen (ZMZ 526690a; Fig. 11) is here selected as neotype.
Diagnosis. Shell large, yellowish, teleoconch sculpture with narrowly spaced ribs on the entire shell, last whorl with shallow furrow, aperture quadrate to subrectangular, peristome disconnected from last whorl.
Description (based on neotype). Shell large, sinistral, oval, yellowish, partly translucent; last whorl only slightly constricted, with a broad and shallow furrow; protoconch large, 1-1.5 whorls, bulbous obtuse, pitted; umbilicus closed, periomphalum narrow; teleoconch sculpture of narrowly spaced ribs on the entire teleoconch; last whorl ascending; aperture quadrate to subrectangular, reinforced by a labial callus, peristome disconnected from the last whorl; apertural rims connected by a large polished callus; aperture with a slightly enlarged process over the left edge; no pleats visible in the aperture; internal lamellar structure not investigated.

Material.
No specimen available. Description (original). "Shell with the penultimate whorl contracted in front, leaving the previous one and lip of the aperture joining regularly costated; lip double; aperture circular and entire. Animal with two tentacles, short and cylindrical, with an active arched motion, as in Helicina. Eyes situated at the base of tentacles inside [Hab. Taviuni, Fiji]." Remarks. No specimen is available, but no collecting was done in Taveuni. This taxon was overlooked by Kobelt (1902). The original illustration is of a shell with an aperture shifted to the left of the shell axis, which indicates a generic placement in Diancta rather than Moussonia or Palaina.

Etymology.
Latin adjective aureus, -a, -um = golden; with reference to the peculiar colour of fresh shells of this species.
Diagnosis. Shell sinistral, yellow, narrow periomphalum, with a few very strong ribs on the last third of the last whorl, internal dentition almost completely reduced.
Description. Shell sinistral, small, of a bright yellow colour; last whorl constricted; protoconch broad, obtuse with a pitted microsculpture; umbilicus closed, very narrow periomphalum; teleoconch sculpture initially of coarse widely spaced ribs, changing to a more dense pattern on the next two whorls, almost smooth on the last whorl (particularly above the aperture), followed by a few very strong ribs on the last third of the last whorl; last whorl slightly ascending; aperture circular, not connected to the last whorl, peristome funnel-shaped, simple; apertural rims connected, with a small parietal shield; no dentition visible in the aperture in frontal view; columellar plate with a narrow internal part, outer part reduced to a basal knob.
Distribution (Fig. 170). Only known from the type locality. Remarks. Diancta aurea sp. n. differs from three species of similar size by the following character states: D. basiplana sp. n. differs in the remarkable form of its enlarged last whorl, D. subquadrata sp. n. in its much finer ribbing pattern on the teleoconch, and D. aurita sp. n. in its characteristic formation of the apertural process and the deep orange apertural shield.  itova, 370-390 m, rainforest, -17.7582 178.4166, leg. Bouchet, 28.08.1998. Etymology. Latin adjective auritus, -a, -um = with long ears. Diagnosis. Large, sinistral shell, yellowish, aperture with an extraordinarily enlarged process over the left edge, aperture orange red.

Diancta aurita
Description. Shell large, sinistral, elongate oval, yellowish; last whorl slightly constricted; protoconch large, bulbous obtuse, pitted; umbilicus closed, narrow concave periomphalum; teleoconch sculpture of widely spaced ribs on the initial whorls, turning to a more densely spaced pattern on the central whorls, and becoming slightly coarser on the last third of the last whorl; last whorl slightly ascending; aperture circular, orange red, peristome doubled, not connected to the last whorl; apertural rims connected; aperture with an extraordinarily enlarged process over the left edge; no pleats visible in the aperture; inside the shell columellar plate with a reduced inner part, and a broad outer part.

Diancta basiplana
Description. Shell large, sinistral, shell colour dull brown; last whorl slightly constricted; protoconch big, bulbous obtuse with pitted microsculpture; umbilicus slitlike closed, periomphalum narrow, flat; last whorl with a broad bulbous expansion, aperture slightly shifted to the left and ascending, basis of the last whorl compressed; teleoconch sculpture of fine regularly spaced ribs, which become coarser on the last third of the last whorl; aperture almost rectangular, peristome doubled; apertural rims connected and detached from the last whorl, with a broad parietal shield; no pleats visible in the aperture; inside the shell with a columellar plate consisting of a twisted tooth-like lamella.  Etymology. Latin adjective controversus, -a, -um = coiling in the opposite direction. Diagnosis. Shell dextral, reddish to pinkish, regularly spaced ribs, last whorl slightly ascending, aperture connected to the last whorl, columellar plate with a strong inner plate, opposite a strong axial palatalis.
Description. Shell dextral, oval, medium sized, reddish to pinkish coloured; last whorl constricted; protoconch broad, obtuse; umbilicus slit-like, concave periomphalum; teleoconch sculpture of regularly spaced fine ribs, ribs become somewhat coarser on the last whorl; last whorl slightly ascending; aperture subrectangular, peristome funnelshaped, doubled; aperture connected to the last whorl with a slight labial callus; no visible pleats in the aperture; inside, columellar plate with a strong inner plate, outer plate less developed, and a basal knob opposite to the inner plate with a strong axial palatalis.
Description. Shell sinistral, oval, small, brownish; last whorl constricted; protoconch broad, obtuse with a pitted microsculpture; umbilicus closed, concave and narrow periomphalum; teleoconch sculpture of fine regularly spaced ribs, in a dense pattern on the upper whorl, pattern more spacious with more coarse ribs on the last whorl; last whorl strongly ascending; aperture circular, connected to the last whorl, peristome funnel-shaped, simple; apertural rims connected, with a broad parietal shield; no dentition visible in the aperture by frontal view; inside with bipartite columellar plate, external part of the plate reduced to a basal knob, internal part a broad lamella, opposite a palatalis (visible in the aperture of fresh shells as an internal knob), a second palatalis just right above the columellar angle, and a parietal lamella present.
Description. Shell dextral, broadly oval, quite large, reddish; last whorl constricted; protoconch broad, obtuse; umbilicus slit-like, concave periomphalum; teleoconch sculpture of regularly spaced fine ribs, ribs slightly coarser on the last whorl; last whorl strongly ascending; aperture subrectangular, peristome funnel-shaped, simple; aperture connected to the last whorl; no visible pleats in the aperture; inside the shell, columellar plate reduced to an almost invisible callus, one palatalis present.
Remarks. Diancta dextra sp. n. differs from the similar D. controversa sp. n. by the more coarse pattern of ribbing, the reduced columellar plate, and the missing palatalis. The two species co-occur in the Wailotua karst. Description. Shell sinistral, large, stout and broad, of a dull brown colour; last whorl considerably constricted; protoconch broad, obtuse with a pitted microsculp- ture; umbilicus closed, very narrow periomphalum; teleoconch sculpture of coarse, widely spaced ribs, with a few stronger ribs on the last third of the last whorl; last whorl ascending; aperture broad and circular, disconnected from the last whorl; peristome funnel-shaped, doubled; apertural rims connected; no dentition visible in the aperture by frontal view; columellar plate reduced, with a narrow basal almost denticle-like callus, no other lamellae present.
Description. Shell sinistral, very small, elongate, yellowish; last whorl strongly constricted; protoconch broad, obtuse with a pitted microsculpture; umbilicus closed, concave periomphalum; teleoconch sculpture of regularly spaced fine ribs, with an abrupt change on the last whorl with ribs becoming very coarse and widely spaced; last whorl only slightly ascending; aperture circular, detached from the last whorl; peristome funnel-shaped, doubled; no dentition visible in the aperture by frontal view; internally with strong palatal lamella visible through fresh translucent shells, columellar plate reduced to a knob-like basal denticle.
Operculum corneous, flat, with a relatively long apophysis, OD = 0.35. Measurements. holotype ( Fig. 32): H = 2.39; D = 1.54; PH = 0.89; PD = 0.91; W = 5.5. Distribution (Fig. 170). eastern part of Viti Levu. Remarks. Diancta distorta sp. n. differs from all the other small Diancta species by its elongate shell and the unique combination of reduced columellar plate and opposing palatal lamella. In its outer shell morphology it resembles D. densecostulata, but in the latter the aperture is always attached to the penultimate whorl (and differs completely in its inner lamellae). Description. Shell large, sinistral, oval, light brown to yellowish; last whorl constricted; protoconch big, bulbous obtuse with microsculpture of minute granules; umbilicus slit-like, closed, periomphalum perspectively broadened; last whorl considerably shifted to the left, only slightly ascending; teleoconch sculpture of fine, regularly spaced ribs, much coarser on the last third of the last whorl and more widely spaced; aperture almost rectangular, peristome doubled; apertural rims connected; aperture shortly detaching from the last whorl with an extraordinarily enlarged ear-like process over the left edge; no pleats visible in the aperture; inside the shell with a single, broad basal columellar plate (Fig. 36, arrows).

Diancta pulchella
Operculum corneous, flat, internally with a broad apophysis, DO = 0.75. Measurements. holotype ( Fig. 35): H = 4.56; D = 3.59; PH = 1.66; PD = 1.61; W = 5. Distribution (Fig. 170). Only known from the type locality. Remarks. Diancta pulchella sp. n. is the largest diplommatinid so far known from Fiji. It cannot be confused with any other Diancta species because of its aperture, which is completely shifted to the left side of the shell. Diancta aurita sp. n. has a similar earshaped apertural process, but differs in all other respects including the orange colouration of its aperture. Diancta basiplana sp. n. differs by its bulbous extension on the last whorl, the attached aperture, the ribbing pattern, and the simple peristomial rim. Etymology. Latin adjective rotundus, -a, -um = rounded; with reference to the shape of the aperture.
Description. Shell sinistral, elongate oval, small, whitish to translucent; last whorl strongly constricted; protoconch small, smooth; umbilicus slit-like open to completely closed, periomphalum concave; teleoconch sculpture of coarse spacious ribs on the upper whorl, fine and dense on the medium and coarse and spacious on the last whorl; penultimate whorl enlarged; last whorl slightly ascending; aperture circular, peristome funnel-shaped, doubled; aperture slightly detaching from last whorl; no pleats visible in the aperture; inside the shell, columellar plate reduced, with a small palatal fold opposite.
Distribution (Fig. 170). Only known from the type locality. Remarks. Diancta rotunda sp. n. is one of the smallest species of the genus in Fiji, along with D. distorta sp. n., D. densecostulata sp. n., D. macrostoma, and D. trilamellata sp. n., but it can be distinguished from these by its enlarged penultimate whorl. Its teleoconch sculpture is similar to that in D. trilamellata sp. n., but the latter species possesses a palatalis and parietalis.  Etymology. Latin prefix sub = somewhat, and adjective quadratus, -a, -um = squared; with reference to the shape of the aperture.
Diagnosis. Shell sinistral, broad, small, brownish, ribbing pattern changing from coarse on the upper whorls to fine on the medium and coarse on the last whorl, aperture circular, columellar plate broad.
Description. Shell sinistral, broadly oval, small, brownish; last whorl considerably constricted; protoconch large, 1-1.5 whorls, pitted; umbilicus closed, periomphalum narrowly concave; ribbing pattern on teleoconch of coarse and spacious ribs on the upper whorl, fine and dense on the intermediate whorls, and coarse and widely spaced again on the last whorl; last whorl slightly ascending and detaching from the last whorl; aperture circular, peristome funnel-shaped, doubled, peristomial rims connected by a broad parietal shield; no pleats visible in the aperture; columellar plate broad, not subdivided, no inner lamellae present.
Diagnosis. Shell sinistral, very small, teleoconch sculpture of coarse ribs, initially widely , then densely, spaced, last whorl ascending, aperture circular, detached from last whorl, with a palatal and a parietal lamella and broad columellar plate.
Description. Shell sinistral, very small, whitish to yellowish; last whorl strongly constricted; protoconch broad, obtuse with a pitted microsculpture; umbilicus closed, very narrow periomphalum; teleoconch sculpture initially of coarse widely spaced ribs, changing to a more dense pattern on the central whorls, with a few very strong ribs on the last whorl; last whorl strongly ascending; aperture almost circular, not connected to the last whorl, peristome doubled and funnel-shaped, apertural rims connected; no dentition visible in the aperture by frontal view; internally with a palatal and a parietal lamella, columellar plate broad, subdivided into an inner and outer part, inner part with a slight notch.
Diagnosis. Shell elongate conical, dextral, oval, almost non-umbilicate; protoconch whorls smooth; teleoconch whorls usually with a blunt keel; whorls completely smooth to finely ribbed, sometimes with fine thread-like spirals; last whorl narrowed; columellaris ends as a tooth-like lamella in a central to basal position in the aperture; internal lamellar system with one columellaris, two parietal lamellae and one to two palatal lamellae. The operculum was not observed. Remarks. The Samoan Pupa problematica Mousson, 1865, the type species of Moussonia, is illustrated here for comparison (Fig. 140, Syntype ZMZ 526751, Samoa, Upolu, H = 1.9 mm). Unfortunately, there are not enough specimens of the type species available to document its inner lamellar system.  -18.952 -178.4533, leg. Bouchet, 11.03.1999, MNHN/1174 Diagnosis. Shell dextral, small, dark brown, teleoconch sculpture of widely spaced ribs with fine periostracal threads, whorls inconspicuously keeled, palatalis short, tooth-like.

Moussonia fuscula (Mousson, 1870)
Description. Shell dextral, small, last whorl not constricted, translucent light to dark brown; protoconch consisting of 2 whorls, granulated; teleoconch of > 5 whorls with an almost inconspicuous keel, sculpture consisting of faint, widely spaced ribs with fine periostracal threads; suture deep; last whorl slightly ascending before aperture; aperture attached to last whorl, rounded, peristomial rim reinforced by a strong white labial callus, columellar side with a strong columellaris; umbilicus closed; internal lamellar system with one columellaris, two parietal lamellae and one palatalis; columellaris a strong lamella, with a well-developed undulation at its end above the aperture; inner parietalis a long thread-like lamella, outer parietalis large, spatulate; palatalis a short lamella, directly above the aperture (can be seen from the outside as a reflecting callus).
Measurements. Lectotype (Fig. 47 Description. shell dextral, medium sized, last whorl slightly constricted, yellowish to red-brown; protoconch of 2 whorls, smooth; teleoconch of > 5 bluntly keeled whorls; sculpture of fine, densely spaced ribs; suture deep; last whorl not or only slightly ascending before aperture; umbilicus almost closed; aperture attached to last whorl, subrectangular, peristomial rim doubled, reinforced by a labial callus, columella with a strong columellaris; internal lamellar system with one columellaris, two parietal lamellae and one palatalis; columellaris a thin lamella, slightly undulating at its end above the aperture, where it is reinforced by a callus; inner parietalis a long lamella, outer parietalis spatulate and oblique; palatalis in a central position above aperture, formed like an undulate lamella and ending in a knob-like tooth visible as a red-brown callus from the outside. Operculum unknown. Measurements. Lectotype (Fig. 50): H = 2.02; D = 1.14; PH = 0.63; PD = 0.65; W = 7.
Distribution (Fig. 170). Eastern part of Viti Levu and the neighbouring island of Ovalau.
Remarks. For a differential diagnosis, refer to M. vitianoides sp. n.  Description. Shell dextral, small, elongate turreted, deep reddish brown; protoconch of 2 whorls, smooth; teleoconch of > 8 well rounded whorls, almost smooth, only a few faint, widely spaced riblets; suture deep; last whorl not ascending before aperture; aperture very small, attached to last whorl, obliquely rounded, peristomial rim reinforced by a strong labial callus, columellar side with a strong columellaris; umbilicus slightly open; internal lamellar system with one columellaris, two parietal lamellae and one palatalis; columellaris a thin lamella, without undulation at its end above the aperture; inner parietalis a long thread-like lamella, slightly overlapping with the second low parietalis; palatalis missing.
Distribution (Fig. 171). Two islands in the Lau archipelago. Remarks. Moussonia acuta sp. n. is unmistakable because of its very narrow shell form, which is unique among Fiji Diplommatinidae. Etymology. This species is named after Gary Barker, formerly of Landcare Research, Hamilton, New Zealand, in recognition for his efforts to get the land snails of Fiji onto the local conservation agenda.
Description. Shell minute, dextral, biconical, last whorl slightly constricted, light brown to yellowish; protoconch consisting of 2 whorls, smooth; teleoconch of > 4 well rounded whorls, sculpture consisting of fine and widely spaced riblets; last whorl only slightly ascending before aperture; aperture attached to last whorl, subquadrate, relatively large, peristomial rim reinforced by a thick white labial callus, columellar side with a strong columellaris; internal lamellar system with one columellaris, two parietal lamellae and one palatalis; columellaris a thin lamella, with a strong undulation at its end above the aperture; inner parietalis a thin lamella, not connected to the second spatulate parietalis; very long palatalis directly above the aperture (can be seen from the outside as a long fine thread), with a central undulation.
Distribution (Fig. 170). Only known from the type locality. Remarks. Moussonia barkeri sp. n. is unique in its combination of a minute shell with an aperture the size of that of larger species. It differs from the similar sized M. minutissima sp. n. by its more obese shell, its long undulating palatalis, and the larger outer parietalis. Etymology. This species is named after Giliane Brodie, lecturer at the University of the South Pacific, to acknowledge and encourage her conversion from nudibranch taxonomy to land snail conservation.
Description. Shell dextral, small, last whorl slightly constricted, translucent light yellow; protoconch consisting of 2 whorls, smooth; teleoconch of > 5 bluntly keeled whorls, sculpture consisting of strong, widely spaced ribs, which can bear a periostracal bristle at the periphery (only in really fresh shells); suture deep; last whorl slightly ascending before aperture; aperture attached to last whorl, rounded, peristomial rim reinforced by a strong labial callus, columellar side with a strong columellaris; internal lamellar system with one columellaris, two parietal lamellae and one palatalis; columellaris a thin lamella, with a strong undulation at its end above the aperture; inner parietalis a short lamella, overlapping with the outer parietalis, which is a low lamella; very short palatalis directly above the aperture (can be seen from the outside as a small reflecting callus).
Description. Shell dextral, very small, last whorl not constricted, translucent light yellowish-brownish; protoconch of 2 whorls, granulated; teleoconch of > 7 bluntly keeled whorls, sculpture of faint periostracal threads; suture very deep; last whorl not ascending before aperture; aperture attached to last whorl, rounded, peristomial rim reinforced by a weak labial callus, columellar side with a strong columellaris; umbilicus closed; internal lamellar system with one columellaris, two parietal lamellae and one palatalis; columellaris a thin lamella, with a strong undulation at its end above the aperture; inner parietalis long, outer parietalis spatulate; palatalis a very long lamella, situated on the left side above the aperture (can be seen from the outside as a reflecting callus).
Distribution (Fig. 171). Only known from the type locality.

Remarks.
Although very similar to M. fuscula, Moussonia longipalatalis sp. n. is treated here as a different species because the latter has a smaller shell, bluntly keeled whorls, and a long and very readily visible palatalis, which is only a short knob-like callus in M. fuscula. Etymology. Latin adjective minutissimus, -a, -um = very small. Diagnosis. Shell dextral, small, light brownish, protoconch granulated, ribs with periostracal threads, inner parietalis very short, palatalis tooth-like directly above aperture.

Moussonia minutissima
Description. Shell dextral, small, last whorl not constricted, translucent light brownish; protoconch of 2 whorls, granulated; teleoconch of > 5 whorls with an almost inconspicuous keel, sculpture of faint, widely spaced ribs with fine periostracal threads; suture deep; last whorl slightly ascending before aperture; aperture attached to last whorl, rounded, peristomial rim reinforced by a strong labial callus, columellar side with a strong columellaris; umbilicus slightly open; internal lamellar system with one columellaris, two parietal lamellae and one palatalis; columellaris a thin lamella, with a strong undulation at its end above the aperture; inner parietalis a very short thread-like lamella, outer parietalis small, spatulate; palatalis tooth-like, directly above the aperture (can be seen from the outside as a reflecting callus).
Distribution (Fig. 171). Only known from the type locality. Remarks. Moussonia minutissima sp. n. is remarkable because of its granulated protoconch. It differs from M. barkeri sp. n. by its reduced tooth-like palatalis and very short inner parietalis, and from M. fuscula by its smaller size and the short inner parietalis. Etymology. Latin adjective obesus, -a, -um = fat. Diagnosis. Shell dextral, broad, bluntly keeled, with widely spaced ribs, inner parietalis long, outer parietalis spatulate, long palatalis, situated above aperture.
Description. Shell dextral, relatively large and broad, last whorl not constricted, deep red-brownish; protoconch of 2 whorls, smooth; teleoconch of > 5 bluntly keeled whorls, sculpture of strong, densely spaced ribs with a fine sculpture of spiral threads (high magnification needed); suture deep; last whorl slightly ascending before aperture; aperture attached to last whorl, subrectangular, peristomial rim slightly reinforced by a weak labial callus, columellar side with a strong columellaris; internal lamellar system with one columellaris, two parietal lamellae and one palatalis; columellaris a thin lamella, with a strong undulation at its end above the aperture with a small denticle on top of the undulating part; inner parietalis a long lamella, which increases in height towards its end, outer parietalis large, spatulate; palatalis above the aperture forming a long and strong lamella.
Description. Shell dextral, small, last whorl well constricted, translucent light yellow; protoconch of 2 whorls, smooth; teleoconch of > 5 well rounded whorls, sculpture of a few faint, widely spaced ribs, shell glossy shining; suture deep; last whorl slightly ascending before aperture; aperture attached to last whorl, rounded, peristomial rim reinforced by a strong labial callus, columellar side with a strong columellaris; umbilicus slightly open; internal lamellar system with one columellaris, two parietal lamellae and one palatalis; columellaris a thin lamella, with a strong undulation at its end above the aperture; inner parietalis a long thread-like lamella, slightly overlapping with the second spatulate parietalis; palatalis extremely long, directly above the aperture, starting as a lamella besides the columellar side of the aperture, ending above the angular edge of the peristome with a small denticle.
Description. Shell dextral, spindle-shaped, last whorl slightly constricted, deeply redbrown; protoconch of 2 whorls, smooth; teleoconch of > 6 slightly shouldered whorls, sculpture of fine, widely spaced riblets; suture deep, with a deep notch dorsolaterally on the last whorl indicating the inner end of the palatalis (see arrows); last whorl slightly ascending before aperture; aperture attached to last whorl, subquadrate, peristomial rim reinforced, doubled, white, columellar side with a strong columellaris; internal lamellar system with one columellaris, two parietal lamellae and one palatalis; columellaris a lamella with a large brown denticle on top of the lamellar area just above the aperture, extending into the interior of the shell, where it abruptly bends upwards; inner parietalis an inconspicuous broad and flat callus, not connected to the outer parietalis, which is a thin, spatulate lamella; palatalis deep inside the shell above the angular edge of the peristome forming a strong, hook-like lamella with a moderately deep corresponding furrow on the outer side of the shell, its inner end indicated by a sutural incision.
Operculum unknown. Measurements. Holotype (Fig. 67): H = 2.46; D = 1.29; PH = 0.8; PD = 0.84; W = 7.5. Distribution (Fig. 170). two localities on Viti Levu. Remarks. Moussonia uncinata sp. n. can be identified by the hook-like palatalis and the small furrow on the last whorl, indicating its end. It has some similarities with M. obesa sp. n., but the latter has stronger ribs, a palatalis parallel to the suture, and non-spathulate prt2. Among the Fiji Moussonia species, M. uncinata sp. n. is one of the largest. It shares the axial and deeply situated palatalis with M. vitianoides sp. n.; for differences, refer to that species.
Description. Shell dextral, small, last whorl almost not constricted, yellow brownish; protoconch of 2 whorls, smooth; teleoconch of > 5 bluntly keeled whorls, sculp- ture of strong, densely spaced ribs; suture deep; last whorl slightly ascending before aperture; umbilicus, slit-like open; aperture attached to last whorl, subrectangular, peristomial rim doubled, reinforced by a strong labial callus, columellar side with a strong columellaris; internal lamellar system with 1 columellaris, two parietal and two palatal lamellae; columellaris a thin lamella, with a strong undulation at its end above the aperture; inner parietalis a long lamella, which increases in height towards its end, shortly overlapping with the outer parietalis, which is a low lamella; first palatalis a fine elongate lamella above the aperture, the second palatalis deep inside the shell above the angular edge of the peristome forming a strong almost axially orientated lamella running from the palatum to the inner basal surface of the whorl, corresponding to a small sutural furrow on the outer side of the shell.
Remarks. The first palatalis is not present in all specimens. M. vitianoides sp. n. can superficially be confused with M. vitiana. It differs from it by the presence of two palatal lamellae, with the second one in an almost axial position. This remarkable feature can also be observed in M. uncinata sp. n., but the latter has a larger, deep brown shell, and lacks the first palatalis. Diagnosis. Shell elongate oval, last whorl not constricted, usually with a bulbous last whorl, aperture in a rather central position in relation to the shell longitudinal axis, without apertural dentition; internal dentition mainly concerns formation of the columellaris, which may be toothed to completely unarmed; operculum with or without concentric lamellae; with a low arcuate ridge on the inner surface. Semper established the name Palaina without providing a description. Kobelt's (1902: 394) definition is undiagnostic, as this author included under this header many species from the Pacific diplommatinid radiation, which can be considered a polyphyletic assemblage: "Shell ovate cone-shaped, in most cases sinistral, with a diverse sculpture. Last whorl constricted at the beginning or the first quarter; aperture without teeth, operculum deeply sunken, uncalcified, circular, with several whorls. Shell elongate oval; no dentition; operculum corneous, with thick concentric ridges" [translated from German].
A re-definition of Palaina was provided by Yamazaki et al. (2013: 16) (Stanisic et al. 2010). Comparing their shells to those from Palau and to those from Fiji that we include in Palaina, they differ by their quite compact and stout outline (the Fiji species are more variable in shape). The inner lamellar system of the Lord Howe radiation is unknown. However, Tillier (1981) illustrated the operculum of P. macgillivrayi, which seems to have a bilobed ridge on the inner surface, and thus differs from what is seen in the Palau species, which have a single strong ridge (Yamazaki et al. 2013: Figs 10A-D), and in the Fiji species, which have a low, inconspicuous rigde. In shell shape and formation of the opercula, the Fiji "Palaina" are close to those from New Caledonia, but unfortunately, Tillier (1981) did not investigate the internal lamellar system in the latter, so potentially useful information is lacking. The species in the New Caledonia radiation have no penis, while the Palau species possess one. Yamazaki et al. (2013) claimed that Tillier (1981) found P. macgillivrayi to also have no penis, a statement that, however, is not explicit in Tillier's text. For Fiji, no information is available in this regard at present. This short review shows that knowledge of this group is patchy. It seems possible that all the different island radiations will have to be separated at the generic level once the full set of characters is known. For the time being, we conservatively apply Palaina in a broad sense to the Fiji radiation, although we anticipate a separation at the generic level (for which the name Macropalaina is available) from the Lord Howe and Palau radiations The Fiji species might not even be monophyletic. Type material. The 2 specimens originally mentioned by Mousson could not be traced in the collection of Mousson in Zurich nor in the collection of the Journal de Conchyliologie in Paris. In a lot in ZMZ, however, originally identified by Mousson as "D. martensi", a specimen similar to the -somewhat sketchy -original illustration of D. ascendens is present. This specimen cannot be considered type material, because it was acquired by Mousson in his collection in 1872, i.e. two years after the description of the species. To stabilize the use of the name, this specimen is here selected as neotype.
Description. Shell sinistral, medium sized, oval, whitish; protoconch acute, granulated; last whorl not constricted with a moderately large bulb; last whorl strongly ascending; teleoconch sculpture of coarse widely spaced ribs; umbilicus slit-like, periomphalum narrow; aperture subquadrate, peristome reinforced by a lip, with two denticles on each side (Fig. 73, arrows), broadly attached to last whorl; no pleats visible in the aperture; internal lamellar system not studied. Remarks. The lot ZMZ 526689 contained a larger number of Diancta martensi (ZMZ 526689c), but also one specimen of P. tuberosa (ZMZ 526689a) and a specimen of P. latecostata (ZMZ 526689b).

Palaina godeffroyana (Mousson, 1870)
Description. Shell sinistral, elongate oval, white to light yellowish; protoconch acute, granulated, consisting of 2 whorls; last whorl not constricted, bulb reduced, inconspicuous; teleoconch sculpture of widely spaced ribs, ribbing pattern slightly wider on the last two whorls; last whorl strongly ascending; aperture circular, in a central position, broadly adhered to the last whorl, peristomial rims connected; umbilicus closed, periomphalum narrow; lamellar system completely reduced; bulb lamella very weak.
Operculum. Outer surface with concentric rings of lamellae, internal surface concave and smooth inside, OD = 0.52.

Palaina latecostata
Description. Shell sinistral, small, broadly oval, whitish to greenish; protoconch acute, granulated; last whorl not constricted, slightly ascending; bulb well developed; umbilicus closed, periomphalum compressed; sculpture of teleoconch whorls with widely spaced ribs; aperture circular, simple, adhered to the last whorl; peristome with a faint labial callus; oblique view into the aperture revealing a strong columellaris; internally, columella obliquely twisted, forming a horizontal lamella in its lower third; a moderately strong bulb lamella present, in some specimens entering the parietum as a thick lamella; small parietalis present.
Operculum corneous, with a long lamella on the outer surface, internally smooth, OD = 0.55.
Description. Shell sinistral, large, elongate spire, white to light yellowish; protoconch acute, granulated, consisting of 2 whorls; initial teleoconch whorls narrow, subsequent whorls rapidly increasing in diameter; last whorl not constricted, bulb of moderate size; teleoconch sculpture of widely spaced ribs with occasionally interspersed smaller ribs, rib pattern constant throughout the whole shell; deep suture and well-rounded whorls; last whorl ascending; aperture circular, in a central position, broadly adhered to the last whorl, peristomial rims connected; umbilicus closed, periomphalum narrow; internally, columella not reinforced with a small knob-like denticle at the base; bulb lamella very weak.
Operculum. Outer surface with concentric rings of lamellae, internal surface concave and smooth inside, OD = 0.91.
Measurements. Possible syntype (Fig. 82): H = 4.8; D = 2.26; PH = 1.53; PD = 1.57; W = 6. Distribution (Fig. 170). several localities on Viti Levu. Remarks. This is the type species of Macropalaina. The character states in this species compare very well with those in Palaina as defined here, the only difference being the remarkable lamellate operculum. Until the diagnostic value of the operculum has been investigated there is no reason to separate Macropalaina from Palaina, and they are here treated as synonyms, as did previous authors before us.
Palaina pomatiaeformis is the largest Palaina species so far known from Fiji. It differs from all other Palaina species by its narrow initial teleoconch whorls and the last whorls that rapidly increase in diameter. This characteristic "Cochlostoma-like" feature prompted Möllendorff to separate it in its own genus. However, an acute protoconch with somewhat narrower upper teleoconch whorls can also be found in P. godeffroyana and other species. Size and shell form make P. pomatiaeformis a species that cannot be confused with any other Palaina species. Type data. No type specimens of D. subregularis could be traced in MNHN or in ZMZ. Under the name D. subregularis, the Mousson collection houses the lot ZMZ 526677 which, according to the handwritten label, originates from "Viti Levu, Graeffe 1872". Although identified by Mousson himself as his D. subregularis, this lot is not type material, because it reached Mousson two years after the description of the taxon, and it does not originate from the type locality. From the same locality "Viti Levu", four specimens in SMF 105079/4 (coll. Möllendorff ex Mousson, also as D. subregularis), had been identified as "cotypes" by A. Zilch. It is highly probable that these specimens also come from ZMZ 526677, and thus were not originally part of the type series. Moreover, SMF 105079/4 consists of three shells that do match with "subregularis" in the sense of Mousson, and one that does not, but is P. godeffroyana. In order to stabilize the application of this name, we here designate a neotype from ZMZ 526677, because the specimens from this lot match the description of Mousson very well. Neotype: subregularis ZMZ 526677a, Viti Levu, coll. Mousson ex Graeffe 1872 (Fig. 86).

Palaina subregularis (Mousson, 1870)
D. graeffei: lectotype, designated by Zilch (1953: 17, pl. 6 fig. 89), SMF 104903/1, Fiji, Viti Levu, coll. Möllendorff ex Mousson. The name graeffei had already been used by Mousson in his collection (ZMZ 526702/many, "Dipl. graeffei Mss., Viti Levu (Graeffe)"), but had remained a manuscript name. The lectotype of graeffei matches the shells in this lot so well that the SMF specimen most probably originates from this lot; however, there is no evidence that Möllendorff ever saw the specimens in the Mousson collection when he published the name Diplommatina graeffei, and the specimens in ZMZ 526702 are not regarded by us as paralectotypes.
Description. Shell sinistral, elongate oval, eroded shells purely white, well preserved specimens with a pattern of brown axial flames or blotches between the ribs; protoconch acute, granulated; last whorl not constricted, slightly ascending; bulb reduced, demarcated by a faint bulb lamella; umbilicus closed, periomphalum narrow; sculpture of teleoconch whorls with widely spaced ribs, ribbing pattern above the aperture somewhat denser; aperture circular, sometimes with a double lip demarcated by a brown line, adhered to the last whorl; oblique view into the aperture revealing a strong columellaris; internally, columella forming a broad lamella extending towards the interior of shell, basally forming a columellar tooth.  (Mousson, 1870). 86 Neotype ZMZ 526677a, Viti Levu, H = 3.5 mm 86 specimen ex ZMZ 526677, last whorl opened to show internal lamellae (enlarged, not to scale) 88 ditto, operculum 88a inner surface, 88b outer surface) 89 Diplommatina graeffei (Möllendorff, 1897) Operculum corneous, outer surface with several concentric lamellae and a single, short raised lamella; internal surface concave, smooth.
Measurements. Neotype of subregularis (Fig. 86) Distribution (Fig. 170). Quite widespread on Viti Levu. Remarks. After a careful comparison of the lectotype of D. graeffei with the rest of the material attributed to P. subregularis, it was not possible to find any discriminating characters between the two taxa besides shell size, and we conclude that the former is a small specimen of the latter.
For a differential diagnosis, refer to P. flammulata sp. n., P. truncata sp. n., and P. parietalis sp. n. Diagnosis. Shell sinistral, small, bulb well developed, whorls widely ribbed, area above aperture fine and densely ribbed, labial callus weak, columella obliquely twisted, truncate with a thick bi-lobed tooth, parietalis a long slightly raised lamella.

Palaina tuberosa (Mousson, 1870)
Description. Shell sinistral, small, broadly oval, faint yellowish; protoconch acute, granulated; last whorl not constricted, slightly ascending; bulb well developed; umbilicus closed, periomphalum narrow; sculpture of teleoconch whorls with widely spaced ribs, area above the aperture with fine and densely arranged ribs; aperture circular, simple, adhered to the last whorl; aperture with a weak labial callus, two small ear-like processes on the upper edges of the peristome; by oblique view into the aperture columellaris visible; internally, columella obliquely twisted, truncate in the lower half forming a thick bi-lobed tooth; parietum with a long slightly raised parietalis in front of the bulb.
Distribution. Vaini-Loba (or Vai-Loba?) on the southern coast of Viti Levu (modern name not identified); not found during the 1998-99 field work.

Remarks.
Palaina tuberosa can easily be confused with P. tuberosissima sp. n., which is similar in shell size and shape. P. tuberosa differs from it by having the dense ribbing pattern of the area above the aperture, the weak labial callus, and the reduced ear-like processes on the peristome. In the internal lamellar system, P. tuberosa has only a bilobed columellar tooth, its parietalis is not spatulate, and a palatalis and second columellaris are missing altogether. Etymology. This species is named in honour of Albert Mousson who pioneered the description of the Fiji diplommatinid fauna.
Diagnosis. Shell dextral, small, bulb inconspicuous, columellaris visible in frontal view forming a short horizontal lamella, bulb lamella visible as a fine white line in frontal apertural view.
Description. Shell dextral, small, broadly oval, whitish to greenish; protoconch acute, granulated; last whorl not constricted, slightly ascending; bulb inconspicuous; umbilicus slit-like, periomphalum narrow; sculpture of teleoconch whorls with widely spaced ribs; aperture subquadrate, with two ear-like processes, simple, adhered to the last whorl; peristome with a labial callus; columellaris visible in frontal view; internally, columellaris forming a short horizontal lamella coiling into the interior of the shell; bulb lamella present, visible as a fine white line in frontal apertural view.
Operculum corneous, strongly concave, with a long lamella on the outer surface, internally smooth, OD = 0.7.
Measurements. Holotype (Fig. 95): H = 3.76; D = 2.3; PH = 1.69; PD = 1.72; W = 6. Distribution. only known from the type locality. Remarks. Palaina alberti sp. n. was identified by Mousson as "Dipl. Godeffroyana var. latecostata", but can easily be separated from that species by its dextral shell. Additionally, it differs from P. latecostata by the columellaris, which in P. alberti is visible in the aperture, and forms a horizontal lamella. No dextral Palaina species is currently known from Fiji.  -17.9816 177.6266, leg. Bouchet, 21.08.1998. Etymology. Adjective formed from the Latin noun flamma = fire, diminutive flammula, to describe the colour pattern of this species.
Diagnosis. Shell sinistral, broadly oval, with a pattern of brown axial flames, large bulb, whorls with widely spaced ribs and occasionally interspersed smaller ribs, columella twisted with a truncate basal tooth.
Description. Shell sinistral, broadly oval, protoconch acute, granulated; basic shell colour yellowish to white, with a pattern of brown axial flames between the ribs; last whorl not constricted, with a large bulb; teleoconch sculpture of widely spaced ribs with occasionally interspersed smaller ribs, rib pattern constant throughout the whole shell; fine spiral threads visible on the upper teleoconch whorls (high magnification required); last whorl slightly ascending; aperture circular, sometimes with a double lip, broadly adhered to the last whorl; umbilicus closed, periomphalum narrow; columella twisted, forming a narrow lamella, and ending in a truncate basal tooth; bulb lamella present.
Description. Shell sinistral, medium sized, broadly oval, light yellowish brownish; protoconch acute, granulated; last whorl not constricted, bulb of moderate size; teleoconch sculpture of widely spaced ribs, rib pattern constant throughout the whole shell; above the aperture, ribs becoming weak or are missing; last whorl slightly ascending; aperture circular, with a double lip, broadly adhered to the last whorl; umbilicus closed, periomphalum narrow; columella only slightly reinforced, bulb lamella weak.
Description. Shell sinistral, small, oval, whitish to yellowish; protoconch acute, granulated; last whorl not constricted, ascending; bulb well developed, laterally compressed, oblique to the shell's axis with a deep basal depression; suture very deep, whorls well rounded; umbilicus closed, periomphalum narrow; sculpture of teleoconch whorls with widely spaced ribs, ribbing pattern denser on the last 1.5 whorls; aperture circular, with a double lip, adhered to the last whorl, but parietal callus slightly detaching; oblique view into the aperture revealing a strong columellaris; internally, columella obliquely twisted, truncate in the lower half forming a basal lamellar callus, parietum with a very long parietalis in front of the bulb; a strong bulb lamella present.
Description. Shell sinistral, medium sized, broadly oval, brownish to yellowish; protoconch acute, granulated; last whorl not constricted, slightly ascending; bulb well developed; umbilicus closed, periomphalum narrow; sculpture of teleoconch whorls with moderately spaced ribs, ribbing pattern above the aperture much denser; aperture subquadrate, double lipped, adhered to the last whorl; peristome reinforced by a strong labial callus; by oblique view into the aperture columellaris invisible; internally, columella only slightly reinforced; bulb demarcated by a faint bulb lamella.
Operculum corneous, outer surface with several concentric lamellae and a single, short raised lamella; internal surface concave, smooth, OD = 0.67.

Palaina parietalis
Description. Shell sinistral, small, elongate oval, white to faintly yellow; protoconch acute, granulated; last whorl not constricted, slightly ascending; bulb reduced, internally demarcated by a faint bulb lamella; umbilicus closed, periomphalum narrow; sculpture of teleoconch whorls with widely spaced ribs, ribbing pattern above the aperture somewhat denser; aperture suboblique, simple, adhered to the last whorl; by oblique view into the aperture columellaris almost invisible; internally, columella twisted, forming a broad triangular lamella, opposite with a perpendicular palatalis, parietum with an elongate parietalis.
Remarks. P. parietalis sp. n. is close to P. subquadrata sp. n. and P. latecostata, but has a strong parietalis and a palatalis, lacking in the latter two species, which can easily be seen by oblique view into the shell.  near summit Uluitova, 370-390 m, rainforest, -17.7582 178.4166, leg. Bouchet, 28.08.1998, MNHN/1. Etymology. Latin adjective sulcatus, -a, -um = with a furrow. Diagnosis. Shell sinistral, small broadly oval, yellow to greenish, bulb reduced, aperture with a large horizontal columellaris, a strong palatalis corresponding to a deep furrow on the dorsal side of the last whorl, elongated parietalis present.
Description. Shell sinistral, small to medium sized, broadly oval, faintly yellow to greenish; protoconch acute, granulated; last whorl not constricted, ascending; bulb reduced; umbilicus closed, periomphalum narrow; sculpture of teleoconch whorls with widely spaced ribs, area above the aperture almost smooth; aperture subquadrate, with a double lip, and two ear-like processes on the upper edges of the peristome; adhered to the last whorl; aperture with a large horizontal columellaris in a central position; internally, columellaris forming a large horizontal lamella of approximately one whorl, slightly bent upwards towards its end; opposite a strong palatalis corresponding to a deep furrow on the dorsal side of the last whorl; an elongated parietalis and a faint bulb lamella present.
Operculum corneous, outer surface with indistinct concentric lamellae and a single, short raised lamella; internal surface concave, smooth, OD = 0.66. Distribution (Fig. 170). Eastern Viti Levu. Remarks. P. sulcata sp. n. is unmistakable for its columellaris, which is unique among all Fiji diplommatinids, because it is formed like a classical columellaris, i.e. a horizontal lamella running into the interior of the shell twisting around the columella. The columella itself is not transformed. Another unique feature is the strong palatalis with the corresponding furrow in the last whorl.
P. sulcata sp. n. is provisionally placed in Palaina, because there is no bulb formation in Diancta, but a constriction of the last whorl, and the columella is usually transformed to form a columellar plate, not present here in P. sulcata. Etymology. Latin adjective, past participle of verb truncare = to truncate. Diagnosis. Shell sinistral, small, bulb well developed with strong bulb lamella, columella obliquely twisted, truncate, basal tooth-like callus, one parietalis Description. Shell sinistral, small, oval, whitish to greyish; protoconch acute granulated; last whorl not constricted, slightly ascending; bulb well developed; umbilicus closed, periomphalum narrow; sculpture of teleoconch whorls with widely spaced ribs; aperture circular, simple, adhered to the last whorl; oblique view into the aperture revealing a strong columellaris; internally, columella obliquely twisted, truncate in the lower third with a basal tooth-like callus, parietum with a small parietalis in front of the bulb and a parietal furrow or depression next to the columella; a strong bulb lamella present.
Distribution (Fig. 170). Only known from the type locality. Remarks. P. truncata sp. n. is close to P. tuberosissima sp. n., but this species has a large parietalis, a lamella in the bulb, and a deep palatalis. It is also similar to P. subregularis, but differs from it in having the twisted columella, a parietalis and a bulb. Etymology. Adjective, derived from Latin tuber = swelling, and suffix -issimus, -a, -um = very.
Diagnosis. Shell sinistral, small, faint yellowish, bulb well developed, whorls with widely spaced ribs, peristome with labial callus, columella obliquely twisted with a second columellaris beyond the bulb, a very long spatulate parietalis and a strong palatalis inside the bulb.
Description. Shell sinistral, small, broadly oval, faint yellowish; protoconch acute, granulated; last whorl not constricted, slightly ascending; bulb well developed; umbilicus closed, periomphalum narrow; sculpture of teleoconch whorls with widely spaced ribs, area above the aperture almost smooth; aperture circular, simple, adhered to the last whorl; peristome reinforced by a strong labial callus, and two ear-like processes on the upper edges of the peristome; by oblique view into the aperture columellaris visible; internally, columella obliquely twisted and reinforced, truncate in the lower half forming a basal knob-like tooth, and a second columellaris beyond the bulb; parietum with a very long spatulate parietalis in front of the bulb; a strong palatalis inside the bulb present.
Operculum corneous, outer surface with several concentric lamellae and a single, short raised lamella; internal surface concave, smooth, OD = 0.67.
Remarks. It is not clear whether Diplommatina paradoxa originates from Fiji or somewhere else. Due to the absence of type material and the imprecise original description, the correct identification is impossible.

Biodiversity
Twelve species of Diplommatinidae were historically known from Fiji, and an additional one (Palaina alberti sp. n.) is described here based on historical material. Of these thirteen species, six are present in the material collected in 1998-99 that forms the basis of the present paper, and seven have not been re-collected: one (Diancta taviensis) from Taveuni and one (D. macrostoma) from Ovalau, two islands that have not been surveyed for land snails since the 19th century; and five species are from Viti Levu (D. quadrata, Palaina ascendens, P. latecostata, P. alberti, P. tuberosa). It is difficult to speculate on whether the cause for not re-collecting them is environmental change -and thus perhaps extinction -or micro-endemism within Viti Levu. The localities for these species are either vague ("Viti Levu") or use 19th century place names ("Tatatan" or "Tatatau", "Vaini-Loba") that cannot be recognized in modern usage. In the 1860-1870s when Graeffe collected in Fiji, access to the interior of Viti Levu was difficult and it is probable that much of his collecting was done near the coast. During the 1998-99 field work, emphasis was placed on the limestone outcrops, and coastal localities were generally avoided precisely because the habitats there are more degraded than in the interior and especially on limestone. The lack of documentation of these five species in 1998-99 does not imply, in our opinion, that they are extinct, or even threatened. Such a statement would require a much more thorough survey.
The 1998-99 field work documented 35 diplommatinid species -six already known and 29 new. Six species (all in Moussonia) were recorded from the Lau Islands, and 29 from Viti Levu, with no overlap between the two guilds. Very limited collecting was done on Vanua Levu, and a single diplommatinid (also occurring on Viti Levu) was found. There are two main karst areas in Viti Levu: a group in the north-east drained by the Wainimbuka river (Wailotua, Wainivesi and Nakorosule karsts), and a group in the center drained by the Sigatoka river (Qalimare, Saweni, Tuvu and Toga karsts). The Wailotua karst is the largest limestone area in Viti Levu. It extends for approximately 4 km along the Wailotua creek, a tributary of the Wainimbuka river, and reaches 425 m on Uluitova Peak. The Nakorosule limestone crops out on the eastern side of the Wainimala river and extends for nearly 2 km. Smaller limestone outcrops are situated in the southwest between Sigatoka and Natadola (Voli Voli), near Suva (Qauia), and near Nabukulevu. There is apparently very little limestone in western and northern Viti Levu, and no sample was taken in that part of the island (Fig. 170).
In the Lau Islands, five islands were visited, with numbers of species on each ranging from one (Evuevu, Thikombia, Navutu-i-Loma) or two (Aiwa, Yagasa Levu) to four (Yacata). Four species are known from single islands (M. brodieae on Thikombia, M. longipalatalis on Navutu-i-Loma, and M. minutissima and M. polita both on Yacata), one was found on two islands (M. acuta on Yacata and Yagasa Levu), and one (M. fuscula) on three, with literature records from a further three. Given the patchiness of our sampling in the Lau Islands (the group consists of some 60 islands), there is no basis to suggest that the species recorded from only one island are single-island endemics. However, it is certain that all -except Moussonia vitiana (which also occurs on Viti Levu) -are Lau Islands endemics, and probable that many are indeed restricted to discrete island groups within the Lau Islands (Fig. 171).
The number of historically known species not re-collected in 1998-99 (7 species), the number of single-site occurrences (14 species), and the numerous islands -including limestone islands -that have not been surveyed at all, all indicate that the 42 species of Diplommatinidae currently known from Fiji represent perhaps only half of the Fiji diplommatinid fauna (Fig. 172). Such numbers approach the famous diplommatinid diversity of Palau (39 described and more than 60 undescribed species - Rundell 2008Rundell , 2010Yamazaki et al. 2013), and surpasses by far the diversity of other South Pacific archipelagos of comparable land area: New Caledonia, 11 species (Tillier 1981), Vanuatu, 2 species (Solem 1959), Samoa, 1 species (Cowie 1998). Lord Howe and Norfolk, both considerably smaller, have 7 and 2 species respectively (Stanisic et al. 2010). While some of these figures probably reflect biogeographic differences, others may, however, merely reflect the lack of focused diplommatinid collecting effort.

Sexual dimorphism
Like all other caenogastropod land snails, diplommatinids have separate sexes, and it is important not to mistake sexually dimorphic individuals as separate species. Sexual dimorphism has been reported in Cochlostomatidae, the sister group of Diplommatinidae from Europe (Raven 1990;Gofas 2001;Reichenbach et al. 2012). It mainly concerns shell size and shell shape, while other shell traits like ribbing pattern and colour variation do not show significant variation between males and females. On average, females have larger shells than males, which may be correlated with reproductive organs differing in volume between males and females -those of the latter being considerably larger, especially when eggs are present in the uterus. These differences are obvious enough that, based on shells alone, a trained person can sex cochlostomatid individuals with an accuracy of 90% (Reichenbach et al. 2012).
This problem has not been sufficiently addressed in Diplommatinidae. Solem (1959: 192) claimed to have observed sexual dimorphism in Palaina from Santo (Vanuatu), but this observation was based on two "sculptural types of shells", and not on preserved animals that could be sexed. Based on the present material from Fiji, sculpture alone is an insufficient guide to species identification, and even more so for recognition of sexes. Solem's hypothesis was repeated by Fontaine et al. (2011: 173, figs 198C, 198D), but again the specimens were not sexed, and thus there is no evidence that Solem's speculation was correct. In the present study, as only dried specimens were available, the animals could not be sexed. However, we could not observe any size differences among shells of a given population, although it should be stressed that diplommatinids are so small that differences in the range of 100-500 μm are not immediately discernible. For this reason, we measured shell height and shell diameter of four sympatric species from the Wailotua karst, D. martensi, D. densecostulata, D. pulchella and D. distorta. Thirty specimens of each species were randomly selected and shell measurements were taken using an optical measuring tool. In all species, there is some variation, with the standard deviation on average being approximately 10%. All species exhibited a single cloud of points with no clear dimorphism in size or shape (Fig. 173, Table 2). There is little morphological overlap between the species, although if the other nine species known from Wailotua were included, this picture may become more complex. Nonetheless, major differences in shell morphology -like presence and absence of a palatal or parietal lamella -confirm that different species, and not different sexes of the same species, are involved. Likewise, Yamazaki et al. (2013) found that differences in shell characters of Palau diplommatinids reflected differences among species and/or subspecies and not sexual dimorphism.

Key to the genera and species of Diplommatinidae from Fiji
This key is based on adult specimens with fully developed apertural characteristics. To facilitate recognition, an overview plate with a frontal view of the species is given for each of the three genera. However, to ensure a reliable identification, shells of a few specimens should be opened to check the internal lamellar system.