Carychium panamaense Jochum

Jochum, Adrienne, Ruthensteiner, Bernhard, Kampschulte, Marian, Martels, Gunhild, Kneubuehler, Jeannette & Favre, Adrien, 2018, Fulfilling the taxonomic consequence after DNA Barcoding: Carychiumpanamaense sp. n. (Eupulmonata, Ellobioidea, Carychiidae) from Panama is described using computed tomographic (CT) imaging, ZooKeys 795, pp. 1-12 : 4-8

Carychium panamaense Jochum sp. n. Figures 2, 3, 4

Carychium panamaense : Weigand et al., 2013: 3, fig. 1 48|C12; Seq. ID: BARCA142-12, BARCA143-12, BARCA144-12

Material examined.

Holotype (NMBE 554428/1 ex AJC 2383): Panama, Chiriquí Prov., Cerro Punta, La Amistad International Park, El Retoño Trail, near Las Nubes Ranger Station; 8.8934278°N, 82.6190528°W, elev. 2239 m, on moist broadleaf litter and twigs; 27 February 2018; leg. Adrien Favre.

Paratypes: locus typicus 3 damaged shells (NMBE 554429/3 ex AJC 2383); 7 specimens in ethanol (NMBE 554432 ex AJC 2382); 5 specimens in ethanol (SMF 349423 ex AJC 2382); 5 specimens in ethanol (MUPADI-Mol.-01-001 ex AJC 2382); 4 specimens in ethanol (ANSP A476441 ex AJC 2382); 5 specimens in ethanol (CM 159907 ex AJC 2382); 3 specimens in ethanol (UF 511987 ex. AJC 2382); data as for holotype.

Diagnosis.

Shell ca. 2 mm in height, transparent, elongate-pupiform with an oblique, ovate-shaped and unequally thickened peristome, with a palatal callus, pronounced parieto-columellar callus and a prominent parietal denticle. Internal coiling of the lamella about the columellar spindle is wide rather than tight.

Description.

Measurements are provided in Table 1. Shell minute, elongate pupiform, transparent when fresh, with about 4.1 convex whorls and a deeply incised suture; occasional, irregular striations or growth lines on the body whorl (see also Jochum et al. 2017, fig. 15). The shell is opaque with age and often superficially degraded with pock marks (due to acidity of the leaf litter). The protoconch is more nipple-like than bulbous. The teleoconch is smooth. Peristome is obliquely auriform, longer than wide, tending to be thinnest on the upper right-hand margin, where it slightly reflects from the body whorl and then curves into a relatively broad, shield-like aspect onto the body whorl (Figs 2A, E, 3A). The peristome is otherwise, uniform in thickness (Figs 2, 3) but becomes thinner towards the edges. A medium-sized parietal denticle is present, the base of which is in line horizontally with the widest, shield-like extension of the peristome onto the body whorl (Figs 2A, E, 3, 4F). Directly opposite the parietal denticle is a thickened palatal callus (Figs 2A, 4F). The lower left columellar margin has a prominently-thickened, parietal-columellar callus (Figs 2A, E, F, 3 A–C, 4F). In aperture facing-right perspective, the peristome is sheer with the body whorl (Fig. 4 G–H). The peristome curves back slightly at the base (Figs 2B, 4C) whereby, the layer of callus on the palatal side forms a small knob on the rim in the aperture facing-left (Fig. 2B) and dorsal (Fig. 4B) perspectives.

Internally, a widely spiraling, sinuous lamella starts at the top of the penultimate whorl (dorsal perspective) (Fig. 4B), which extends laterally in aperture facing-left and aperture facing-right perspectives (Fig. 4D, H). The degree of fullest sinuosity varies in the configuration of the lower primary lamella from an accentuated, oblique-elongated S-form (Fig. 2F) to a slightly curved aspect in the ventral perspective (Fig. 4F). The thick, upper curvature of the lamella forms the upper part of the elongated S shape (Fig. 2F). The general curvature of the lamella about the columella is wider than narrow along the entire length of the columellar spindle. Viewed from the umbilical perspective (Fig. 4J), the rim of the peristome is thin and widely flared. In live individuals, the outmost edge of the peristome appears white (Fig. 6D).

Differential diagnosis.

Differs from congeners presented in Jochum et al. (2017), imaged here (Figs 4 K–T, 5), by its apertural morphology and large apertural size: long, obliquely-auriform, widely-flared aspect of the thinly-rimmed peristome (seen best from umbilical perspective) (Fig. 4) and the wide coiling of the lamella about the columellar spindle. Although the peristome mostly resembles that of C. belizeense ( Jochum et al. 2017, fig. 11A, I), the generally broad, shield-like extension of the peristome onto the body whorl differentiates this species from C. belizeense as well as from its Southeastern USA, Caribbean and Central American congeners. Though the S-shaped configuration of the primary lamella (ventral view) (Fig. 2F) is closest to that of C. belizeense (Fig. 5), C. hardiei (Fig. 5) and C. zarzaae (Fig. 4P), the abapical onset of the lamella in the penultimate whorl and the general extant of sinuosity along the entire length of the columella in relation to the columellar spindle is unique to each species in both the ventral and dorsal perspectives. The tongue-like flexion of the primary lamella is a specific configuration occurring in three different perspectives within the shell of each of these species: C. hardiei (dorsal perspective) (Fig. 5), C. zarzaae (aperture side-left perspective) (Fig. 4R) and C. jardineanum (ventral perspective) (Fig. 5). This down-turned, tongue-like flexion is not at all present in C. panamaense sp. n. (Fig. 4). The configuration of the lamella in C. panamaense is spatulate (Fig. 4H) rather than tongue-like in form (Fig. 4R).

DNA barcode data can clearly delineate Carychium panamaense sp. n. from all other North American, Caribbean and Central American taxa ( Weigand et al. 2013, Jochum et al. 2017, fig. 3).

Etymology.

The new species is named after Panama, the Central American country of origin.

Distribution.

Only known from the type locality along the short distance, Retoño trail, ca. 50 m before the first river crossing, Parque International La Amistad, Chiriquí Prov., Panama.

Ecology.

In moist broadleaf forest litter and twigs ( Quercus and Lauraceae ) at the base of trees and palm trees in secondary tropical rainforest (Fig. 6 A–B).

Conservation.

In the flat area of the Retoño trail, where water accumulates under trees during rainfall, live Carychium panamaense sp. n. was found in relative abundance, suggesting that it has optimum ecological conditions to survive there. Carychium panamaense sp. n. is only known from Parque International La Amistad, Chiriquí, Panama, a Bi-National Biosphere Reserve (RBA) located between Panama and Costa Rica and designated a UNESCO World Heritage Site. Despite its being found in a Biosphere Reserve, on a global scale, its current distribution may well be limited to the immediate area of Retoño trail. In conjunction with the Guidelines for the IUCN Red List (IUCN Standards and petitions Subcommittee 2014), it is considered a Critically Endangered narrow range endemic (CR B1) and as such, warrants immediate conservation priority.

Remarks.

The type locality of the first recorded species of Carychium in Panama, C. zarzaae (Boquete), is approximately 97 km southeast of the type locality of C. panamaense sp. n. near the Las Nubes Ranger Station ( Chiriquí). From the site of its closest known Central American relative, C. costaricanum (San Gerardo de Dota, San José, Costa Rica) ( Weigand et al. 2013), the distance is 263 km.