Carychium mariae Paulucci, 1878

Weigand Marie-Carolin Götze Adrienne Jochum, Alexander M., 2012, Outdated but established?! Conchologically driven species delineations in microgastropods (Carychiidae, Carychium), Organisms Diversity & Evolution (New York, N. Y.) 12 (4), pp. 377-386 : 382-383

Morphospecies Carychium mariae Paulucci, 1878

The translucent, thin, uniform whitish shell “differs from all others by its more obese form” ( Paulucci 1878), which is ovate-conic and ranges from 1.6–1.8 mm in height and 0.8– 0.9 mm in width. The surface sculpture consists of prominent, fine, thread-like closely spaced, transverse striae coursing the 4–4 ½ convex whorls. The spire is more convex and less cylindrical than in C. tridentatum . The characteristic, sinuous parietal lamella resembles that of C. tridentatum in the slightly increased degree of undulation as well as its orientation in relation to the aperture opening. Our FE-SEM frontal, ventral and side observations and image data reveal neither new dimensions nor any distinguishable differences ( Zimmermann 1925; Watson and Verdcourt 1953; Lozek 1957; Pintér 1967; Kerney et al. 1979; Bank and Gittenberger 1985) ( Figs. 2 , 3 ). Finally, the eight most characteristic specimens identified as C. mariae within our study resemble those of investigated C. mariae syntypes ( Fig. 4 ).

Our conchological observations of the three Carychium morphospecies are in congruence with Bank and Gittenberger’ s (1985) conchological analyses of C. mariae (their figs. 9-14), C. tridentatum (their figs. 15-28) and C. minimum (their figs. 29-30) ( Table 3). These observations also underscore fossil analyses performed by Strauch (1977) in which he describes the degree of characteristic sinuosity of the parietal lamella in association to its placement on the columellar apparatus while viewing the shell ventrally. Although the three morphospecies in this study depict varying degrees of sinuosity from the posterior view, the concept is the same: flexure of the S-sinuate lamella varies with each individual shell and individual species.

DNA barcoding

The alignment of 96 COI sequences of Carychium mariae , C. minimum and C. tridentatum morphospecies and barcodes of the in- and outgroup taxa ( Table 2) has a total length of 655 base pairs. The resulting neighbor-joining tree shows a significant split between an evolutionary significant unit (ESU) including the eight most characteristic C. tridentatum specimens (ESU1) and another ESU including the eight most characteristic specimens of C. mariae and C. minimum (ESU2) (bootstrap support 100, Fig. 5a, b ). The averaged between-group genetic variability (ESU1/ESU2) is 5.9% with averaged within-group variabilities of 0.6% and 1.7% for ESU1 and ESU2, respectively. DNA barcoding of the ESUs using in- and outgroup barcode IDs ( Table 2) clearly identifies the specimens of ESU1 as C. tridentatum and all members of ESU2 as C. minimum with maximal genetic variability lower than 3.2% (barcoding gap for Carychiidae, Weigand et al. 2011 ) within both groups.

Figures

Fig. 2 FE-SEM results of conchological details of Carychium tridentatum, C. minimum and C. mariae morphospecies. Shells are arranged in the following order (left to right): ventral view, side view, dorsal view, columellar view. Locality information can be retrieved from Table 1

Fig. 3 FE-SEM image of typical morphospecies Carychium mariae Paulucci, 1878 (frontal view) from locality 5

Fig. 4 Two syntype specimens of Carychium mariae Paulucci, 1878. Depicted are syntypes stored in the Museo di Storia Naturale dell’Università di Firenze, Sezione di Zoologia de “La Specola” with collection number MZUF GC/11971; 6 sp.; Italy, Lombardy region (MN), Castel Goffredo; M. Paulucci. Additional syntypes (not shown) are MZUF GC/11985 (1 sp.), MZUF GC/13599 (32 sp.) and MZUF GC/ 13600 (202 sp.)

Fig. 5 a Range of conchological variability for the parameters shell height (x-axis) and the ratio shell height/width (y-axis). The eight most characteristic specimens per morphospecies are indicated by a circle (Carychium mariae), square (C. minimum) and triangle (C. tridentatum), respectively. Dark grey, more typical C. tridentatum specimens; light grey, more typical C. mariae specimens; typical C. minimum individuals are in between those two extremes. b Neighbor-joining