Triphora scylla, Fernandes, Maurício R. & Pimenta, Alexandre D., 2015

Fernandes, Maurício R. & Pimenta, Alexandre D., 2015, Five new species and two records of Triphorinae (Caenogastropoda, Triphoridae) from Brazil, Zootaxa 4012 (3), pp. 493-513 : 509-511

Triphora scylla sp. nov.

( Figure 8 )

Type material. Holotype: MZSP 119013, J. Coltro coll., iv/1992. Paratypes: Brazil: Rio Grande do Norte state: MNRJ 26242, BPot 2-MR44 [2]; MNRJ 26243, BPot 1-MR41 [2]. Bahia state: MNRJ 32959, 15º33’44”S, 38º44’23”W, 38 m, 2011 [1]. Espírito Santo state: MNRJ 30749, 19º25’37”S, 39º22’22”W, 43 m, x/2003 [2]; MZSP 119014, type locality, J. Coltro coll., iv/1992 [1]; IBUFRJ 7568, 20º47’S, 40º26’W, 26/viii/1979 [1]; MNRJ 31043 [2], MNRJ 31056 [1]: 20º47’S, 40º34’W, iii/2010; MNRJ 33023, 20º47’S, 40º34’W, ix/2007 [4]. Rio de Janeiro state: MNRJ 18593, HAB 13-H3 [1]; IBUFRJ 19594, REVIZEE C1-D3 [1].

Other material examined. Brazil: Maranhão state: IBUFRJ 17368, Banco Álvaro, Parcel Manoel Luís, 18/ vii/1977 [1]. Rio Grande do Norte state: MNRJ 31637, BPot 2-MR42 [8]; MNRJ 31642, BPot 1-MR43 [10]; MNRJ 31644, BPot 1-MR41 [2]; MNRJ 31645, BPot 1-MR44 [3]; MNRJ 31648, BPot 2-MR44 [5]; MNRJ 31650, BPot 1-MR42 [9]; MNRJ 31651, BPot 1-MR45 [2]; MNRJ 32058, BPot 1-MR32 [1]. Bahia state: IBUFRJ 19520, REVIZEE C5-13R [1]; MNRJ 33815, 18º07’24”S, 38º21’00”W, 55 m, 21/ix/1995 [2]. Espírito Santo state: IBUFRJ 19463, REVIZEE C1-C65 [1]; IBUFRJ 19497, REVIZEE C1-C65 [1]; MNRJ 30718, 19º25’34”S, 39º22’16”, 42 m, x/2003 [1]; MORG 52249, REVIZEE C1-VV22 [1]; IBUFRJ 19544, REVIZEE C1-VV21 [1]; IBUFRJ 19521, 20º47’S, 40º26’W, 29/viii/1979 [1]; MNRJ 31034 [1], MNRJ 31045 [1], MNRJ 31094 [1]: 20º47’S, 40º34’W, iii/2010; IBUFRJ 19514, 21º15’S, 40º20’W, 28/viii/1979 [1]. Rio de Janeiro state: MNRJ 17943, HAB 13-H3 [1].

Type locality. Exit of Guarapari canal, Guarapari, Espírito Santo state, Brazil.

Etymology. The specific name refers to the monster Scylla , from Greek Mythology. Epithet as a noun in apposition.

Diagnosis. Reticulated embryonic shell; median spiral cord emerges between the end of sixth to the end of tenth teleoconch whorl; teleoconch with two white initial whorls, remainder with background light brown to dark cream, dark inter-nodular spaces, whitened nodules; adapical and median spiral cords darker than abapical one.

Description. Shell sinistral, elongated, conical, profile rectilinear to slightly curvilinear, reaching 6.66 mm in length, 1.80 mm in width. Light brown to golden protoconch; teleoconch with about two white initial whorls, remainder whorls with background light brown to dark cream, dark inter-nodular spaces, whitened nodules; adapical and median spiral cords darker than abapical one, especially on nodules; base with same color as background of shell. Protoconch conical, 0.41–0.54 mm in length, 0.34–0.40 mm in width, with 4.5 to 5 convex whorls; embryonic shell dome-shaped, with reticulated sculpture; larval shell with two spiral cords, adapical one weakening and disappearing in the last whorl; about 30 almost rectilinear to slightly sigmoid axial ribs. Teleoconch with up to 13 whorls; two spiral cords (adapical and abapical) on the first whorl, abapical one continuous with that of protoconch; median spiral cord emerges close to adapical cord, between end of sixth and end of tenth whorl, reaching same size as abapical cord (adapical one slightly more pronounced than others in late whorls) after 1 to 2.5 whorls; 16 to 19 almost orthocline to slightly opisthocline axial ribs; rounded nodules of medium size; distinct but little developed suture, with a small sutural cord; moderately to weakly nodulose subperipheral cord, weakly nodulose to wavy adapical basal cord, wavy abapical basal cord; two small supranumerical cords may develop, one between median and abapical spiral cords, the other between abapical and subperipheral cords; aperture ovate; anterior canal directed backward/downward, moderately small and open, but crossed in its base by projection of outer lip; posterior canal as a large notch, not detached from aperture.

Remarks. Triphora scylla sp. nov. varies greatly relative to the emergence and strengthening of the median spiral cord on the teleoconch, as it can emerge between the end of the sixth and the end of the tenth whorl, reaching the same size of the abapical cord after one to 2.5 whorls ( Fig. 8 F). Length of protoconch also varied considerably (0.41–0.54 mm). All other features were consistent between shells, disregarding different maximum size attained at the adult stage.

The color pattern of T. scylla is similar to that of Similiphora intermedia ( C. B. Adams, 1850) , a very common species in the western Atlantic (e.g., Rolán & Fernández-Garcés 1995; Redfern 2013), with the predominance of brown bands over the adapical and median spiral cords on the teleoconch; however, the distinction between darker internodular spaces and lighter nodules is much more evident in T. scylla ( Fig. 8 A–C). In addition, there are differences in the emergence of the median spiral cord on the teleoconch (end of sixth to end of tenth whorl in T. scylla ; fourth or fifth whorl in S. intermedia ), number of protoconch whorls (4.5 to 5 in T. scylla , Fig. 8 I; about six in S. intermedia ), embryonic shell sculpture (reticulated in T. scylla , Fig. 8 J; with granules in S. intermedia ) and which spiral cord weakens in the last larval shell whorl (adapical cord in T. scylla , Fig. 8 I; abapical cord in S. intermedia ).

Triphora scylla can be differentiated from Nanaphora leei by the elongated shell profile, more heterogeneous coloration between spiral cords on the teleoconch ( Fig. 8 A–C), less nodulose subperipheral and basal cords ( Fig. 8 H) and nodules with a reduced size ( Fig. 8 F). One of the shells illustrated by Redfern (2013: fig. 368A) as Monophorus ateralbus resembles T. scylla , but differs in having a slightly ovoid shape (elongated in T. scylla ) and an even more heterogeneous coloration between adapical/median (brown) and abapical (white) spiral cords than T. scylla .

The embryonic shell sculpture of T. scylla is reticulated, thus superficially resembling the cruciform tubercles of the genus Monophorus Grillo, 1877 . The genera Nanaphora and Sagenotriphora Marshall, 1983 also possess reticulated embryonic shells, however their typical species have a curvilinear shell profile, almost ovoid, instead of the elongated shape of T. scylla ; in addition, T. scylla has a later emergence of the median spiral cord on the teleoconch, especially when comparing with Sagenotriphora . In this case, it is preferable to maintain T. scylla in Triphora s. l., awaiting knowledge of the species’ anatomy and morphology.

Geographic distribution. Brazil: Maranhão, Rio Grande do Norte, Bahia to Rio de Janeiro.

Bathymetric distribution. Subtidal to 80 m.

Figures

FIGURE 8. Triphora scylla sp. nov. A. MZSP 119013, holotype, 6.27 mm long. B. IBUFRJ 7568, paratype, 4.00 mm long. C. MNRJ 18593, paratype, 4.41 mm long. D, F, H, same shell as C. E, G, I – K, same shell as B. Scale bars: A – E, 1 mm; F – H, 500 µm; I, K, 100 µm; J, 50 µm.