Koreozospeum nodongense Lee, Prozorova & Jochum

Jochum, Adrienne, Prozorova, Larisa, Sharyi-ool, Mariana & Pall-Gergely, Barna, 2015, A new member of troglobitic Carychiidae, Koreozospeumnodongense gen. et sp. n. (Gastropoda, Eupulmonata, Ellobioidea) is described from Korea, ZooKeys 517, pp. 39-57 : 43-46

Taxon classification Animalia Pulmonata Carychiidae

Koreozospeum nodongense Lee, Prozorova & Jochum sp. n. Figures 3, 4, 5, 6, 7, 8, 9, 10, 11

" Carychium " sp. Min, Lee, Koh and Je, Mollusks in Korea. Min Molluscan Research Institute, Seoul, Korea. 566 pp., 342−343, fig. 1080. 2004

" Zospeum " sp. Prozorova, Lee and Zasypkina, Korean Journal of Soil Zoology 15(1−2): 1−4, figs 1-3. 2011

Material.

Type material. Holotype (NMBE 534197/1): South Korea, North Chungcheong Province, Danyang County, Nodong cave, 36°57.186'N, 128°22.938'E, alt. ca. 271 m, moist muddy walls in cave, 13.01.2000, leg. Jun-Sang Lee.

Paratypes: locus typicus: 3 fragments (NMBE 534361/2), data as the holotype; 1 broken shell (IBSS FEB RAS 7787), ibid.; 5 shells, 1 broken (ZIN RAS 1), ibid.

Diagnosis.

Shell small, thin, ovate-conic, smooth, fine spiral rows of interconnected pits constant throughout teleoconch, plicate apertural lip may or my not be present (side profile).

Description.

Koreozospeum nodongense sp. n. is characterized by a very small, alabastrine, ovate conical shell with 5 regular, moderately increasing whorls. The penultimate whorl is slightly angularly shouldered at the uppermost extension of the peristome in left and right profile positions (Fig. 3 B–C). Peristome oblong, auriform, oblique to shell axis, partially adnate to ultimate whorl, otherwise slightly detached (Fig. 3K), more or less thickened (Fig. 3A, D–E); the lip is folded back onto the body whorl and thickly plicate 3/4 of the lip side-view height (Figs 3C, 4B, E); deep umbilical notch (Figs 3 H–I) with wrinkles projecting into notch behind peristome region (Fig. 4D); robust columellar lamella running into the shell interior (Figs 3A, D–E, 5 I–K). The protoconch is obtuse and shows a pattern of spiral interconnected pits (Fig. 4); the teleoconch bears tightly spaced irregular spiral striae of densely interconnected pits (Figs 4, 9) and shows a marbled surface pattern of faint, horizontally-elongated chevrons intercalating with each successive whorl (Fig. 5 A, C). Suture irregular and shallow, bordered by white marginal zone at each increasing abapical whorl (Figs 3C, F, 4). Interior perspectives show a parietal structure consisting of a partially discontinuous lamellar ridge on the roof of the penultimate whorl (Fig. 4 I–K), which then develops into the uniformly shaped annular lamella running directly under the penultimate whorl into the aperture. The columella is moderately slender, clavate (Fig. 5 G–H) with a single, annular lamella (Fig. 5 G–L).

Measurements

(in mm). Holotype (NMBE 534197/1) (Figs 3 A–G, 7): H = 1.72; SW = 1.19; HLWH = 1.13; PH =.78; PD =.69; SA = 68.6; W = 5.65; WD =.81. See also Table 1.

Etymology.

The new species is named after Nodong cave, the type locality.

Type locality.

South Korea, North Chungcheong Province, Danyang County, Nodong cave, 36°57.186'N, 128°22.938'E, alt. ca. 270 m, moist muddy walls in cave.

Distribution.

Only known from the type locality.

Ecology.

Suggested mix of volcanic elements in cave mud of Nodong cave.

Conservation status.

A cursory search through the Internet indicates that the region harboring caves encompassed within the administrative boundaries of Danyang County is greatly threatened. Due to the abundance of limestone in the area, cement factories are big industries there. Of more immediate threat, however, is the frequent human traffic that the caves of Nodong, Gosu and Cheondong receive in light of their popularity as tourist attractions. To exacerbate concerns, a newly built stairway into the deepest, darkest sections of the cave has made Nodong more accessible ( Lee 2012). Since Koreozospeum nodongense sp. n. is known to live in only one locality and the area is potentially declining due to human encroachment, this species is Critically Endangered (CR) under IUCN criteria ( IUCN 2014).

Remarks.

Koreozospeum nodongense sp. n. appears to be polymorphic in regards to the configuration of a plicate versus non-plicate apertural lip (side view). This elaboration of the lip was apparent in two shells (NMBE 534197/1; ZIN RAS 1) of the five examined shells (1 juvenile with undeveloped lip). We have little doubt that the plicate and non-plicate specimens co-occurring at Nondong cave are conspecific. Prozorova et al. (2011) initially examined the paratype specimen (IBSS FEB RAS 7787) using SEM (Fig. 4). This work revealed microstructural pitting on the protoconch in sync with the concentric pitting pattern reported by Jochum (2011) as a consistent character for the worldwide members of the extant Carychiidae . Protoconch pitting is also known in Eastern European carychiid fossils examined via SEM ( Strauch 1977, Stworzewicz 1999, Harzhauser et al. 2014a, 2014b, Jochum et al. 2015). In congruence with the findings of Prozorova et al. (2011), the fragments of Koreozospeum nodongense sp. n. here show tightly spaced irregular spiral striae of densely interconnected pits with some occasional, non-pitted patchy zones over the entire teleoconch (Fig. 9). This dense pattern of total teleoconch pitting is also found in Zospeum isselianum Pollonera, 1887 and Zospeum bellesi Gittenberger, 1973 (Jochum, unpublished data).

The SEM-EDX analysis (Fig. 10 A–B) of the surface structure located in the central zone of the fragment edge and the internal surface of the shell shows varying concentrations of the same elements, including calcium (Ca), aluminum (Al), silicon (Si), oxygen (O) and carbon (C) for these two separate regions of the shell. A band (Fig. 11A) of likely volcanic origin of the mud (i.e. lava and alkali basalt) is indicated on the surface of one of the shell fragments. This band contains fractions of the elements calcium (Ca), aluminum (Al), silicon (Si), oxygen (O), carbon (C), iron (Fe), zinc (Zn), chromium (Cr), chlorine (Cl), magnesium (Mg) and potassium (K). The non-banded region of shell (Fig. 11B) shows varying concentrations of calcium (Ca), aluminum (Al), silicon (Si), oxygen (O), carbon (C) and iron (Fe).

Interestingly for Koreozospeum nodongense sp. n. is that the trace elements, aluminum (Al) and silicon (Si), might potentially be involved in the biomineralization process of the shell matrix. It is not clearly discernable whether or not they are intrinsic to the shell or represent contaminants from the substrate. Further study, independent of this work, involving major- and trace element analysis coupled with isotope geochemical analysis might suggest the relatively large variability of elements found in our SEM-EDX analyses to be due to the heterogeneous nature of different magmas mixing at different stages of their evolution in historic volcanic eruptions in South Korea ( Brenna et al. 2012). Eroded lava particulates and ash may well constitute the sediment overlying the Ordovician limestone of Danyang County.