Update on the status of the remaining Hawaiian land snail species Part 4: Punctidae and Endodontidae

                                 Norine W. Yeung and Kenneth A. Hayes

    For the fourth installment of our updates on the status of the Hawaiian land snail fauna
we discuss the Hawaiian families in the superfamily Punctoidea: Punctidae (Fig 1A) and
Endodontidae (Fig 1C, D).  Previously we reported on some of the smallest Hawaiian snails, the minute (<4 mm in shell height) Pupillidae, but these snails are not the smallest in the Hawaiian Islands.  Punctidae are commonly called “dot snails” because many are about 1 mm in shell
diameter, resembling little dots. They have a Holarctic distribution but with only one
currently recognized monotypic genus in Hawaii. But as we have seen, land snails
globally, and particularly in Hawaii, are ripe with cryptic species and the Hawaiian
Punctidae may harbor as many as nine undescribed species in the Bishop Museum
Malacology collection (Solem 1983). Their relationship to the majority of other
pulmonates remains uncertain, but in their phylogenetics analyses Wade et al (2006)
recovered a well supported clade containing the Charopidae, Otoconchidae and
Punctidae.  Based on our recent surveys and preliminary molecular analyses,
we have three native punctids and a nonnative species that had been previously mistaken to be a Hawaiian punctid, Paralaoma servilis (Fig 1B; Christensen et al. 2012). Most of these species
were recorded in high elevation forests but in low densities (<5 individuals at a given
site). Due to their size, these snails are often difficult to find and additional surveys and
assessments need to be made to update their taxonomy, distributions and conservation
status.

Family: Punctidae
Genus: Punctum
Number of recognized species: 1
Number of species found in recent surveys: 3 (2 undescribed)
Historical distribution: Oahu, Hawaii
Current distribution: Kauai, Oahu, Maui, Molokai, Hawaii
Conservation status: Threatened

    The Endodontidae, endemic and highly diverse in the Pacific islands, are restricted to
Polynesia, Lau Archipelago, and Palau (Solem 1976, 1990). In Hawaii, there are 33
recognized species with more than 200 undescribed taxa in the Bishop Museum
Malacology collection (Solem 1990). Endodontids have been thought of as the most
primitive 'higher' pulmonates (clade Sigmurethra) based on morphology (Solem 1983,
Tillier 1989), leading Bouchet & Rocroi (2005) to place them with the Punctidae in the
sigmurethran superfamily Punctoidea. However, they were not included in the molecular
analyses of Wade et al (2006), who found no support for this hypothesis (sensu
Bouchet & Rocroi 2005).

    Endodontids are highly threatened (Solem 1990, Sartori et al 2013, 2014) and in
Hawaii, all but three species are likely extinct. Solem (1990) reported that no live
Endodonta were collected on the main Hawaiian Islands since 1940 and the only
species left in this genus is on Nihoa along with a Cookeconcha species. He reported a
few Cookeconcha individuals alive in 1962 and M. Hadfield found only a couple in the
1980s, both in the Waianae Mountains of Oahu. Solem concluded that all low and midelevation
species, which accounts for the majority of the diversity, were extinct by 1960
and the remaining (< 5%) are confined in high elevation refugia. Meyer (2006) reported
the rediscovery of a remnant population of Coohkeconcha in the Waianae Mountains of
Oahu. Our recent surveys, have confirmed the persistence, although in small
populations, of Endodonta sp. on Nihoa and two Cookeconcha spp. (Waianae
Mountains, Oahu). Unfortunately, the Cookeconcha species reported from Nihoa in the
1980s was not found (Conant et al. 1983).

    Unlike the highly endangered Amastridae and Achatinellinae, there are currently no
captive rearing efforts for the remaining Hawaiian Endodontids. Unless there are
management plans in place to protect these remaining species, this family will likely be
extirpated from Hawaii in the next decade, and we will have lost another of these
evolutionary treasures. Along with them go the stories they tell about the history of
these islands and the fauna that have come to inhabit them.

Family: Endodontidae
Genus: Cookeconcha, Endodonta, Nesophila, Protoendodonta
Number of recognized species: 33
Number of species found in recent surveys: 3 (2 of which are undescribed)
Historical distribution: Kauai, Oahu, Maui, Lanai, Molokai, Hawaii, Northwestern
Hawaiian Islands
Current distribution: Oahu, Nihoa
Conservation status: Threatened

References

Bouchet, P. & Rocroi, J.P.  2005. Classification and nomenclator of gastropod families.
Malacologia 47: 1397.

Christensen, C.C., Yeung, N.W., & Hayes, K.A. 2012. First records of Paralaoma
servilis (Shuttleworth, 1852) (Gastropoda: Pulmonata: Punctidae) in the Hawaiian
Islands. Bishop Museum Occasional Papers 112: 37.

Conant, S., Christensen, C.C., Conant, P., Gagne, W., & Goff, M.L. 1983. The unique
terrestrial biota of the Northwestern Hawaiian Islands. Proc. Symp. Resource Invest.
Northwestern Hawaiian Islands, 2527 May 1983:7794.  Sea Grant Coli. Prog.
University of Hawaii, Honolulu.

Cowie, R.H., Evenhuis, N.L. & Christensen, C.C. 1995. Catalog of the native land and
freshwater molluscs of the Hawaiian Islands. Backhuys Publishers, Leiden. vi + 248
pp.

Meyer III, W.M. 2006. Records of rare grounddwelling
land snails on O ‘ahu. Bishop Museum Occasional Papers 88: 5758.

Solem, A. 1983. Endodontoid land snails from Pacific islands (Mollusca: Pulmonata:
Sigmurethra). Part II. Families Punctidae and Charopidae. Zoogeography. Field
Museum of Natural History, Chicago. [ix] + 336 p.

Solem, A. 1990. How many Hawaiian land snail species are left? and what we can do
for them. Bishop Museum Occasional Papers 30: 2740.

Tillier, S. 1989. Comparative morphology, phylogeny and classification of land slugs and
snails (Gastropoda: Pulmonata: Stylommatophora). Malacologia 30: 1303.

Sartori, A.F., Gargominy, O. & Fontaine, B. 2012. Anthropogenic extinction of Pacific
land snails: a case study of Rurutu, French Polynesia, with description of eight new
species of endodontids (Pulmonata). Zootaxa 3640: 343372.

Sartori, A.F., Gargominy, O. & Fontaine, B. 2014. Radiation and decline of endodontid
land snails in Makatea, French Polynesia. Zootaxa 3772.1: 168.

Wade, C.M., Mordan, P.B. & Naggs, F. 2006. Evolutionary relationships among the
Pulmonate land snails and slugs (Pulmonata: Stylommatophora). Biological Journal of
the Linnean Society 87: 593610.

Figure 1: Representatives of the Hawaiian Punctoidea A) native Punctum sp., B) nonnative
Paralaoma servilis C) Endodonta sp. D) Cookeconcha hystricella adult and
juvenile. Scale bar = 1 mm.