Spixia coltrorum, Simone, 2012

Simone, Luiz Ricardo L., 2012, Taxonomical Study On A Sample Of Pulmonates From Santa Maria Da Vitória, Bahia, Brazil, With Description Of A New Genus And Four New Species (Mollusca: Orthalicidae And Megalobulimidae), Papéis Avulsos de Zoologia 52 (36), pp. 431-439 : 431-439

Spixia coltrorum new species

( Figs. 9-14 )

Types: Holotype MZSP 103920 .

Paratypes: MZSP 103922 , 2 shells ; MZSP 103921 , 1 shell , USNM, 1 shell; MNRJ, 1 shell; MZSP 103923 , 8 shells; all from type locality .

Type locality: BRAZIL. Bahia; Santa Maria da Vitória , ~ 13°24’S, 44°12’W, ~ 460 m of elevation (Coltro col., i/2012) .

Diagnosis: Shell with superior half clearly narrower than inferior half, in a non-uniform growth. Sculpture of delicate, uniform axial riblets, opaque surface.

Peristome partially projected, with 4 teeth of somewhat same size and equidistant.

Description: Shell up to 45 mm; outline somewhat turriform, elongated; width ~36% of length ( Figs. 9-11 ). Color white, with scanty axial pale brown spots randomly distributed in last whorls. Protoconch of 2 rounded whorls, sculptured by delicate reticulate of spiral and axial lyre; each cord very narrow and low, separated from each other by distance equivalent to 3-times its width; both spiral and axial cords predominating or a weak predominance of axial cords ( Fig. 13 ); limit with teleoconch unclear; mostly eroded and absent amongst specimens ( Fig. 11 ). Teleoconch of more than 8 whorls; whorls profile almost straight, weakly convex; suture weakly deep. Sculpture a series of delicate and uniform axial riblets, ~ 110 in penultimate whorl. Superior half of spire clearly narrower than inferior half, marked by a somewhat abrupt increase, whorls not uniformly growing ( Figs. 9-10 ). Last whorl uniform with preceding whorls, marked by pair of grooves 1/6 whorl preceding peristome, corresponding to teeth of outer lip; anterior most groove weakly deeper than posterior groove ( Fig. 12 ). Peristome oval, deflected, with ~32% of shell length and ~73% of shell width; weakly prosogyre ( Fig. 10 ). Outer lip arched, with short straight middle region; inner lip strongly concave, superior half weakly convex, covered by thin callus with similar width than remaining peristome. Peristome with 4 teeth of somewhat similar size and equidistant from each other ( Figs. 9, 11 ); parietal tooth located approximately at middle region of callus; palatal tooth located just anterior to middle inflexure of inner lip, this tooth largest; two teeth in outer lip, one located in its middle level, another located slightly at right from anterior corner, this tooth being smallest. Umbilicus opened, narrow, partially covered by inferior half of inner lip, flanked by blunt oblique fold running parallel to furrow of anterior peristome tooth ( Figs. 12, 14 ).

Measurements (in mm): Holotype: 40.0 by 16.0; Paratype MZSP 103921: 40.6 by 16.2.

Distribution: Known only for type locality.

Habitat: Caatinga environment.

Material examined: Types.

Etymology: The specific epithet is in honor of the Coltro brothers, José and Marcus, who contribute greatly with study material, including the present one.

Discussion: The genus Spixia so far comprised four species ( Simone, 2006:172), all of relatively large size, and with entire, rounded peristome, possessing 4 well-developed teeth, which characterizes the genus. From the species, the most similar is Spixia striata (Spix, 1827) , from which S. coltrorum differs by wider umbilicus, opaque surface, more acuminate spire, and by proportionally larger aperture. A single species was never figured, S. hillairii (Gray in Pfeiffer, 1845), but according to the description, S. coltrorum differs by the white peristome ( S. hillairii has it pink), in having more teleoconch whorls ( S. hillairii has 6.5 whorls), and in lacking so developed sculpture ( Pfeiffer, 1845:84). S. coltrorum differs from S. charpentieri Pfeiffer, 1850 in being larger, in having sharper pointed aspire, narrower protoconch, and in lacking fifth tooth in outer lip. S. coltrorum still differs from S. paraguayana (Ancey, 1892) by less developed peristome, by paler color, and by less developed axial sculpture.

The interesting axial brown spots somewhat randomly disposed in the spire ( Figs. 9-11 ) is a current feature amongst the odontostomines, and well developed in S. coltrorum . One of the main features of the species, the different growth between superior and inferior halves of the spire, is very clear in holotype ( Figs. 9-10 ), while it is not so clear in other species ( Fig. 11 ). Other interesting finding is the loss of the protoconch in most specimens ( Fig. 11 ). From the examined ones, only 3 of them possess preserved protoconch. The structure is fractured in the remaining specimens, with a calcified scar.

Figures

FIGURES 1‑14: Shell of types: 1-8) Kora corallina new species; 1) Holotype, apertural view (H 43.4 mm); 2) Same, right view; 3) Same, dorsal view; 4) Same, detail of sculpture of penultimate whorl; 5) Same, detail of apical region, frontal-slightly apical view; 6) Same, detail of umbilicus, anterior-slightly left view; 7) Paratype MZSP 103911, frontal view (H 42.9 mm); 8) Paratype MZSP 103912, frontal view (H 48.9 mm); 9-14) Spixia coltrorum new species; 9) Holotype, apertural view (H 40.0 mm); 10) Same, right view; 11) Paratype MZSP 103921, frontal view (H 40.6 mm); 12) Same, anterior view; 13) Holotype, detail of apical region in profile; 14) Paratype MZSP 103921, detail of umbilicus, anterior-slightly left view.