Trochida

Simone, Luiz Ricardo L., 2024, New species, misidentifications and problematic taxonomy of some Atlantic South American marine mollusks: a review, Papéis Avulsos de Zoologia 64, pp. 1-104 : 8-11

Order Trochida Superfamily Trochoidea

Family Calliostomatidae Genus Calliostoma Swainson, 1840

Calliostoma soror Simone & Dornellas , new species ( Figs. 5-6 ) https://zoobank.org/ CDE3E0AC-2CEB-47BA-998B-EEDB2896B840

Types: Holotype MZSP 121819 , spm . Paratypes: MZSP 166230 , 1 shell with same data as holotype, MZSP114401 , 1 shell from type locality (Abbate col., 15.vii.2013) ; BRAZIL. Espírito Santo; Trindade (Oceanic) Island, Enseada do Lixo ( Paredão ), 20°31′29.8″S 29°19′43.9″W, 15.4 m, MZSP 121827 , 1 shell (J.B. MendonÇa col., 04.xi.2014), Andradas , 20°28′47.69″S 29°18′24.03″W, MZSP 104811 , 1 shell (C.H. Guimarães col., 23.i.2012), coast between Andradas and Tartagugas, 20°30′11.85″S 29°19′11.79″W, MZSP 136531 , 1 spm (J.B. MendonÇa col., 05.xi.2013) .

Type locality: BRAZIL. Espírito Santo ; Trindade Island, Farol , 20°29′52.3″S 29°19′15.6″W [Joel Braga MendonÇa col., 08.iv.2014] .

Diagnosis: Trindade species with ~ 10 mm of adult shell and suture well-marked. Sculptured by spiral cords composed of successive nodes; cords interspaces smooth, equivalent to cords width. Umbilicus mostly closed. Epipodium with papillated edge, and 5 tentacles in left side,with tentacle 2 bifid. Osphradium small. Radula with narrow and tall rachidian, with sharp pointed, curved tip; robust lateral teeth.

Description: Shell ( Figs. 5 A-E, H-M, 6A-D) about 10 mm; trochiform, as tall as wide. Walls thick, iridescent inside ( Fig. 5A, K ). Color light orange-brown; with small brown spots, as wide as spiral cords, relatively densely distributed in some specimens, joined with some axial white bands ( Fig. 5 H-J), similar pattern, but more scantly distributed in other specimens ( Fig. 6 A-C); white bands absent with scanty brown minute spots in other specimens ( Fig. 5 A-C), up to some specimens practically unicolor ( Fig.5 K-M),with only some scanty spots in inferior surface; umbilicus always white ( Figs. 5C, J, M , 6C ). Protoconch usually dark brown, protruded, with 1 whorl, of ~ 0.5 mm; first 0.5 whorl smooth, last 0.5 whorl with strong, successive axial threads ( Figs. 5D, E , 6D ). Spire with angle ~70, teleoconch of ~7 convex whorls; suture relatively deep, performing angle ~150°. Sculpture of punctuated spiral cords, 7 in penultimate whorl; smooth interspaces, with same width as cords; each cord composed of successive, aligned hemispheric punctuations, very evident in most specimens ( Fig. 5 A-E, K-L), but in rare cases cords slightly smooth in last whorl, being punctuated in spire and in inferior surface ( Fig. 6 A-C); last whorl with ~25 spiral cords.Aperture rounded,occupying ~45% of shell width, ~36% of shell height; prosogyre, ~30° with longitudinal axis. Outer lip with cutting edge, undulating reflecting spiral sculpture. Inner lip with strong vertical rafter as edge, flanked by shallow ( Fig. 5A, H ) to relatively deep ( Figs. 5K , 6A ) furrow; remaining as smooth callus. Umbilicus usually totally occluded by callus ( Fig. 5C, J ) more rarely with shallow concavity ( Fig. 5M ), still rarer with deeper concavity ( Fig. 6C ).

Operculum ( Fig. 5F, G ): Rounded, highly multispiral, nucleus central; margin flexiclaudent, fragile; inner surface glossy. Head-foot of ~½ whorl ( Fig. 6 F-G), head as wide as foot; ommatophores (om) elongated, with dark eye at tip; cephalic tentacles (te) located just dorsal to ommatophores, tapering uniformly. Snout (sn) of ⅙ whorl. Foot large (~75% of head-foot volume), pigmented by light brown, with small white spots; cephalic flaps (cf) relatively small, simple; epipodium as short fold, with papillated edge ( Fig. 6H : ep), bearing 4 right, and 5 left epipodial tentacles ( Figs. 6F : 1-5, G: 1-4), each tentacle simple, tapering uniformly up to pointed tip, anterior tentacle as largest; second left tentacle small, white, bifid. Columellar muscle (cm) of 1.5 whorl, right posterior side slightly longer ( Fig. 6H ). Opercular pad ( Fig. 6H : op) in middle level of dorsal foot surface.

Pallial cavity of ~ ⅕ whorl ( Fig. 6E ). Gill very elongat- ed, posterior half of uniform width, anterior half tapering gradually up to bluntly pointed tip. Gill suspensory stalk (gs) with almost half of gill length. Osphradium (os) small, located in base of gill suspensory stalk. Rectum (rt) narrow, simple, full of fecal matter. Anus (an) siphoned (non-sessile), located posterior from mantle edge, close to right limit of mantle cavity.

Radula ( Fig. 6 I-K) about twice odontophore length. Rachidian occupying ~10% of radular ribbon width, ~twice longer than wide; stem rectangular; tip strongly curved inwards, tapering up to sharp pointed tip, having minute secondary cusps at both edges. Lateral teeth as 5 pairs ( Fig. 6J ), base wide, oval, ~ ⅓ of rachidian width; abrupt diminishing in long, flattened rod, as long as rachidian; narrow, arched inwards, tip sharp pointed; distal half of this rod with both edges bearing aligned small secondary cusps, each secondary cusp barb-like, minute, very narrow and pointed. Marginal teeth with ~35 pairs ( Fig. 6I, K ), mote central teeth ~twice longer than rachidian, ~ ⅓ its width; elongated, ~10-times longer than wide; basal 80% weakly arched, tip 20% strongly arched inwards,slightly broader, with both edged bearing 12-15 pairs of secondary cusps, each cusp triangular, ~3-times longer than wide in base, located close from each other; marginal row strongly arched, teeth gradually diminishing towards edges, more marginal teeth ~ ⅓ size of more central teeth; inner set of cusps slightly longer than outer set of cusps.

Etymology: The specific epithet is based on the Latin word soror , meaning sister, in allusion in being sister species of C. depictum Dall, 1927 from the mainland coast.

Distribution: Endemic of Brazilian oceanic islands of Trindade and Martin Vaz.

Habitat: on rocks, from intertidal up to ~ 10 m, usually found by diving.

Measurements (W, H in mm): Holotype MZSP 121819 ( Fig. 5 A-C):8.3 by 8.3. Paratypes:MZSP 121827 ( Fig. 5 H-J): 9.9 by 10.0; 114401 ( Fig. 5 K-M): 7.7 by 7.9; 104811 ( Fig. 6 A-C): 10.5 by 9.3.

Additional material examined: BRAZIL. Espírito Santo; Trindade(Oceanic)Island, PontadaCalheta, 20°30′18.72″S 29°18′31.67″W, MZSP 136733 , 4 spm (J.B. MendonÇa col., 25.vi.2015), 20°30′28.3″S 29°18′38.8″W, MZSP 104780 , 4 shells (C.H. Guimarães col., 10.ii.2012), Tartaruga, 20°31′03.93″S 29°18′08.45″W, MZSP 104150 , 1 shell (C.H. Guimarães col., 27.ii.2012), Andradas , 20°30′45.7″S 29°18′21.9″W, MZSP 140568 , 6 shells (J.B. MendonÇa col., 21.vii.2013), 20°28′47.69″S 29°18′24.03″W, MZSP 105364 , 1 spm (06.ii.2012), Enseada do Lixo , 20°31′43.5″S 29°19′28.1″W, MZSP 105380 , 1 shell (21.ix.2012), Farrilhões, 20°31′22.4″S 29°19′52.0″W, MZSP 115734 , 2 spm (08.vii.2013), off E of, 20°30′15″S 29°18′22″W, 8 m, MZSP 101197 , 1 shell (23.vii.2011) ; Ilha de Martin Vaz, West coast, 20°28′32.32″S 28°52′00.38″W (23.vii.2013), MZSP 115412 , 4 shells, MZSP 115403 , 1 spm .

Remarks: the present species I coauthored with Ana Paula S. Dornellas [Universidade Federal de Sergipe, E-mail: [e-mail]], a Vetigastropoda specialist. Calliostoma soror is only similar to C. depictum in the Brazilian region,as both species have deep suture,relatively small size, and the shell color pattern. Calliostoma soror possibly is derived from an isolated C. depictum population that reached the remote Trindade Island, or both species are derived from the same calliostomatids branch. Calliostoma depictum was recently reviewed, including anatomical aspects, which facilitates the present comparison ( Dornellas & Simone, 2013). Only some details distinguish both species. Calliostoma soror has its shell with the spiral cords entirely composed of successive nodes, this does not occur in C. depictum , except for its first whorls, but the nodes fuse with each other, producing smooth spiral cords at least in the last two worlds ( Dornellas & Simone,2013); C.soror has punctuated spiral cords um to the last whorl. A single exception was found ( Fig. 6 A-C), but the smooth spiral cords are restricted to last whorl and to superior region only.The spiral arrangement of nodes in C. soror in first whorls are coarser and fewer than that of C. depictum , in the third whorl, for example, C. soror has 4 spiral cords, while C. depictum has 5. The suture of C. soror is usually shallower, while that of C. depictum usually is deeper.The umbilicus of C. soror is closed in most specimens ( Fig. 5C, J ), slightly opened umbilicus is exceptional; wile C. depictum the umbilicus is always deep. Related to the anatomy, C. soror differs in having 5 epipodial tentacles in left side, with the tentacle 2 bifid ( Fig. 6F ), while C. depictum has 4 epipodial tentacles in both sides. The epipodium edge is entirely papillated in C. soror ( Fig. 6H : ep), while it is smooth in C. depictum . The projected portion of the gill and of the anus of C. soror ( Fig. 6E : an, gs) are longer than those of C. depictum . The osphradium of C. soror ( Fig. 6E : os) is very small if compared to that of C. depictum ( Dornellas & Simone, 2013: fig. 79). The radula of C. soror ( Fig. 6 I-K) adds more distinctions if compared to that of C.depictum ( Dornellas & Simone, 2013: figs. 48-50); the rachidian of C. soror is much narrower and longer, with a terminal tip much more pointed than that of the other species; the lateral teeth of C. soror are more robust, while those of C. depictum are almost filiform; the marginal teeth are similar in shape, but differ in number, being mush more abundant, ~50 pairs. There is no other Calliostoma species in which C. soror can be confused.

Figures

Figure 5. Calliostoma soror shells and operculum of type specimens:(A-G) Holotype MZSP 121819 (W 8.3 mm); (A) frontal view; (B) apical view; (C) inferior view; (D) detail of apex, apical view, scale: = 0.5 mm; (E) same, profile; (F) operculum, holotype, outer view (W 3.5 mm); (G) same, inner view; (H-J) paratype MZSP 121827 (W 9.9 mm), frontal,apical and inferior views;(K-M) paratype MZSP 114401(W 7.7 mm),frontal,apical and inferior views.

Figure 6.Calliostoma soror shells and anatomy of type specimens:(A-C) paratype MZSP 104811 (W 10.5 mm), frontal,apical and inferior views;(D) detail of apex of paratype MZSP 114401, apical view,scale: = 0.5 mm; (E-H) holotype details of anatomy, scales:= 1 mm; (E) pallial roof, ventral-inner view; (F) head-foot,left view;(G) same,right view; (H) same,ventral view;(I-K) holotype radula in SEM;(I) detail of right side,scale:= 100 µm;(J) detail of central region,scale:= 30 µm; (K) detail of marginal region,scale:= 100 µm.