Friday, February 21, 2020

[Mollusca • 2020] Craspedotropis gretathunbergae • A New Species of Cyclophoridae (Gastropoda: Caenogastropoda), discovered and described on A Field Course to Kuala Belalong Rainforest, Brunei

Craspedotropis gretathunbergae 
Schilthuizen, Lim, van Peursen, Alfano, Jenging, et al., 2020

Terrestrial Caenogastropoda form an important but threatened component of the Borneo tropical rainforest malacofauna, where the group is nearly as rich in species as the Stylommatophora. They are, however, more sensitive to drought, temperature extremes and forest degradation.

New information:
On a field course at Kuala Belalong Field Studies Centre in Brunei Darussalam (Borneo), a new caenogastropod species, belonging to the genus Craspedotropis, was discovered by the course participants. The participants decided to name the species Craspedotropis gretathunbergae n. sp., in honour of the climate change activist Greta Thunberg, as caenogastropod land snails, such as this species, are likely to suffer because of climate change.

Keywords: Land snails, Borneo, lowland dipterocarp rainforest, new species

Figure 1. Craspedotropis gretathunbergae n. sp., holotype (IBER-UBD 7.00141), shell in apertural view. Photo by Pierre Escoubas.

Figure 2. Active individual of Craspedotropis gretathunbergae n. sp. (paratype, IBER-UBD 7.00142), taken from a video file (Suppl. material 1). Image by Pierre Escoubas.

Figure 3. Craspedotropis gretathunbergae n. sp. (paratype, IBER-UBD 7.00143) a, shell with operculum in apertural view. b, detail of the body whorl in lateral view. c, detail of the shell in umbilical view.

Craspedotropis gretathunbergae, sp. n.

Nomenclature: Craspedotropis Blanford 1864 sensu Vermeulen (1999). 
Type species: Craspedotropis cuspidata (Benson 1851)

Diagnosis: Amongst the Bornean cyclophorids, Craspedotropis gretathunbergae n. sp. is most similar to C. borneensis (Godwin Austen 1889), which, however, is somewhat less slender, has 7 - 9 spiral ribs and more broadly reflected apertural lip. In addition, the operculum of C. borneensis has raised whorl margins, which is not the case in C. gretathunbergae n. sp. Other Asian species, with which the new species may be confused, are: (i) Cyathopoma conoideum Sykes 1898, which has a more slender shell and the spiral ribs arranged in a different pattern, with the second rib located just above the suture; (ii) C. sivagherrianum Beddome 1875, which is smaller, has 7 spiral ribs and a nearly closed umbilicus; (iii) C. beddomeanum Nevill 1881, which has more (7 - 8) and more prominent, spiral ribs, more globular whorls and a rounder aperture; (iv) C. procerum Blanford 1868, which is stockier, has 9 - 12 spiral ribs and a peristome that is strongly thickened by folds.

Etymology: We name this species in honour of the young climate activist Greta Thunberg, because caenogastropod microsnails from tropical rainforests, like this new species, are very sensitive to the droughts and temperature extremes that are likely to be more frequent as climate change continues. Via mutual contacts, we have approached Ms. Thunberg and learned that she would be 'delighted' to have this species named after her.

Following Recommendation 51C of the Code (ICZN 1999), if it is desired that authorship of the name be included as part of the name, instead of listing all authors, the species can be referred to as Craspedotropis gretathunbergae Schilthuizen et al., 2019, provided that all authors of the name are cited in full elsewhere in the same work, either in the text or in a bibliographic reference.

Distribution: Borneo: Brunei Darussalam: Temburong District: Ulu Temburong lowland rainforest.

Ecology: In tropical mixed dipterocarp lowland rainforest. All individuals were found alive at the foot of a steep hill-slope, next to a river bank, foraging at night on the upper surfaces of green leaves of understorey plants, up to 1 m above ground level.

Taxon discussion: 
The generic classification of minute cyclophorids in Southeast Asia is somewhat confused. The genera Craspedotropis Blanford 1864, Cyathopoma Blanford 1861 Blanford and Blanford 1861, Jerdonia Blanford 1861 (Blanford and Blanford 1861; sometimes considered a subgenus of Cyathopoma) and Ditropopsis Smith 1897 appear poorly defined and may be partly overlapping or synonymous (Vermeulen et al. 2015, Vermeulen 1999). In its general shell form (a tall conical shell with spiral ribs), the present species is similar to several species of Cyathopoma (e.g. the South Asian C. conoideum Sykes 1898, C. sivagherrianum Beddome 1875, C. beddomeanum Nevill 1881 and C. procerum Blanford 1868) and Craspedotropis, especially C. borneensis (Godwin Austen 1889), known from Sarawak. Given the geographical proximity of the latter, we have tentatively placed the new species in the same genus, Craspedotropis.

All work described in this paper (fieldwork, morphological study, microphotography, taxonomic description and diagnosis) was carried out in a field centre with basic equipment and no internet access, by untrained ‘citizen scientists’ guided by expert scientists, on a 10-day taxon expedition. While we are aware that this way of working has its limitations in terms of the quality of the output (for example, we were unable to perform dissections or to do extensive literature searches), the benefits include rapid species discovery and on-site processing of materials.

 Menno Schilthuizen, Jonathan P. Lim, Anthonie D. P. van Peursen, Massimiliano Alfano, Awang Bikas Jenging, Daniele Cicuzza, Alexandre Escoubas, Pierre Escoubas, Ulmar Grafe, Jamil Ja, Peter Koomen, Aleks Krotoski, Denise Lavezzari, Laura Lim, Rudie Maarschall, Ferry Slik, Derek Steele, Dennis Teck Wah Ting, Ine van Zeeland and Iva Njunjić. 2020. Craspedotropis gretathunbergae, A New Species of Cyclophoridae (Gastropoda: Caenogastropoda), discovered and described on A Field Course to Kuala Belalong Rainforest, Brunei.  Biodiversity Data Journal. 8: e47484. DOI: 10.3897/BDJ.8.e47484