Partula lutaensis, Sischo & Hadfield, 2021

Sischo, David R. & Hadfield, Michael G., 2021, The tree snail on Rota Island, Northern Mariana Islands, long identified as Partula gibba (Partulidae), is a different species, ZooKeys 1037, pp. 105-118 : 105

publication ID

https://dx.doi.org/10.3897/zookeys.1037.56303

publication LSID

lsid:zoobank.org:pub:CE4FE521-0DEC-485F-863E-32CB91BAAA67

persistent identifier

https://treatment.plazi.org/id/65D4AC75-488B-4A29-9773-5E0F5FB25449

taxon LSID

lsid:zoobank.org:act:65D4AC75-488B-4A29-9773-5E0F5FB25449

treatment provided by

ZooKeys by Pensoft

scientific name

Partula lutaensis
status

sp. nov.

Partula lutaensis sp. nov.

Type material.

Holotype. Bishop Museum BPBM 284888 Fig. 3 View Figure 3 . Entire specimen collected by Jill Liske-Clark, 20/11/2014 from type locality. Paratypes. BPBM 284889, 2 specimens collected by Jill Liske-Clark, 20/11/2014, from type locality, and BPBM 284890, 3 specimens collected by Jill Liske-Clark, same date, from a second location on Rota Island, Commonwealth of the Northern Mariana Islands.

Type locality.

Rota Island, Commonwealth of the Northern Mariana Islands (CNMI).

Diagnosis.

Shell. Shell dextral, moderately thin, ovate-conic, slightly perforate; umbilicus open; whorls moderately convex, suture adpressed; aperture ovate-elongate, slightly oblique; outer lip reflexed, thick, glossy; parietal lip glossy with light or dark coloration; color of embryonic whorls and post-embryonic whorls variable from shades of brown, buff, white and yellow with prominent white subsutural band; Measurements (N = 48 specimens from five lots in BPBM collections from Rota): height (= length) 15.98 mm, s.d. 0.75 mm; width, 10.64 mm, s.d., 0.24 mm. See Figure 4 View Figure 4 for examples of shell color variation. Shell greatly resembles those of Partula gibba on Guam and Saipan ( Crampton 1925).

Distinguishing shells of P. lutaensis from those of P. langfordi .

Shell length of P. langfordi (M = 13.83 mm, s.d. = 0.37 mm, N = 47) was significantly shorter than the length of P. lutaensis sp. nov. (M = 15.98 mm, s.d. = 0.75 mm, N = 48), t(82) = -13.91, P <0.001. Similarly, shell width of P. langfordi (M = 9.74 mm, s.d = 0.36 mm) was significantly less than that of P. lutaensis sp. nov. (M = 10.64 mm, s.d = 0.24 mm), t(90) = -8.02, P <0.001 (Fig. 5 View Figure 5 ).

Male reproductive system.

The male reproductive system of Partula gibba figured by Kondo (1955, 1970) and Gerlach (2016) is highly variable. In specimens we examined (Fig. 6A View Figure 6 ), the vas deferens entered the penis very near its top, leaving the upper portion of the penis, attached to the retractor muscle and called the caecum by Gerlach (2016), to be very short. In specimens of P. radiolata , the entry of the vas deferens was about 1/5 to 1/4 of the length of the penis below the retractor-muscle attachment (Fig. 6B View Figure 6 ). However, the male duct was distinctive in P. lutaensis sp. nov. by the bulge or shoulder at the top of an expanded caecum, proximal to the vas deferens. In the male system of P. lutaensis sp. nov., the attachment of the vas deferens was consistently more distal than in either P. gibba or P. radiolata (Fig. 6C View Figure 6 ); the insertion was close to 1/3 of the length of the penis below the retractor-muscle attachment. In no other regard were there any distinctive differences among the penial structures of these three species. The lower attachment of the vas deferens to the retractor muscle in both P. lutaensis sp. nov. and P. radiolata is concordant with their placement as sister taxa in phylogenetic reconstructions of the group. Kondo (1970) found no differences between the male reproductive tract of P. langfordi and P. gibba . We include a modified version of his drawing with ours for comparison (Fig. 6D View Figure 6 ).

Ecology.

Type and paratype specimens were found on Epiprenmum aureum and Tectaria crenata (J. Liske-Clark, Northern Mariana Department of Fish and Wildlife, personal communication).

Etymology.

The specific epithet Partula lutaensis recognizes Luta, the indigenous Chamorro name for the island of Rota.

Kingdom

Animalia

Phylum

Mollusca

Class

Gastropoda

Order

Stylommatophora

Family

Partulidae

Genus

Partula