Drymaeus currais, Simone & Belz & Gernet, 2020

Simone, Luiz Ricardo L., Belz, Carlos Eduardo & Gernet, Marcos de Vasconcellos, 2020, A new species of Drymaeus endemic from Currais Archipelago, Paraná, Brazil (Pulmonata, Bulimulidae), Papéis Avulsos de Zoologia 60, pp. 1-11 : 2-10

Drymaeus currais new species

( Figs. 1‑36 ) urn:lsid:zoobank.org:act:D17AD2E5-D03C-447A-95E0-DFAB83F34F12

Types: Holotype: MZSP 150548 ( Figs. 2-4 ) . Paratypes: MZSP 135683 (19 dissected specimens), LEBIO 577, 5 specimens, all from type locality.

Type locality: Brazil. Paraná ; off Pontal do Paraná, Currais Archipelago, Guapirá Island , 25°44′09.32″S, 48°21′55.34″W (Belz, Gernet & Colley col., 2015) .

Additional non‑type material examined from type locality: MZSP 29634 , 2 dissected specimens (01.xii.1988) ; MZSP 135684 , 3 specimens, MZSP 135685 , 13 specimens, MZSP 136031 , 2 specimens, MZSP 136032 , 5 specimens, MZSP 143544 , 3 specimens (26.iii.2015) .

Etymology: The epithet is in apposition, as a reference to the location of occurrence, derived from Currais Archipelago.

Diagnosis: shell conical, aperture ample, weakly deflect- ed. Color white-cream, mostly with strong axial, dark brown spots; peri-umbilical area lacking spots; some rare specimens uniformly yellowish beige. Secondary ureter closed only in posterior 2/3, furrow-like in third preceding pneumostome. Pulmonary vases particularly dense, mainly on third preceding pneumostome. Anus external to pneumostome, opened directly outside. Aperture of salivary glands lateral in middle level of buccal cavity. Intrinsic pair of odontophore muscles m7 originating in cartilages close to m6; presence of odontophore pairs m1a and m3. Sigmoid intestinal loop relatively short. Penis slender and long, lacking clear inner chambers. Inner spermoduct of spermoviduct protected by tall fold. Seminal receptacle small, with additional elongated diverticulum called genital appendix. Albumen gland duct single, elongated. Pleural ganglia inconspicuous.

Description

Shell: ( Figs. 1-9 ) adult shell around 35 mm, conical-oval; apex bluntly acuminated; greatest width on last whorl; width ~1/2 shell length. Basal color white to pale-cream; pattern of dark-brown spots arranged in irregular axial bands, slightly more concentrated in middle region of whorls; peri-umbilical area flanked by area lacking spots ( Figs. 2-6 ); dark spots absent in ~10% of specimens, being purely yellowish-cream ( Figs. 7-8 ). Spire angle ~55°. Protoconch of 2 whorls, ~6% of total shell length, uniformly sculptured by delicate reticulate pattern ( Fig. 9 ), with ~25 spiral lines in last whorl; transition to teleoconch clear, slightly prosocline ( Fig. 9 : arrow).Teleoconch smooth, except for growth lines, of ~4 whorls. Whorls profile slightly convex. Suture well-marked, slightly oblique (diagonal) to columellar axis. Aperture prosocline (~20° from longitudinal general axis) ( Fig. 3 ), oval; ~50% of shell length, ~60% of shell width. Peristome slightly reflected, especially on columellar region, partially covering umbilicus ( Figs. 2, 5, 7 ). Body whorl ~1/2 shell length. Umbilicus narrow.

Head‑foot: of usual shape. Color uniformly clear. Columellar muscle thick, 1.8 whorls in length.

Mantle organs: ( Figs. 23-26 ) mantle border thick, lacking pigments. Pneumostome (pn) protected by ventral, right simple flap (mf), with ~1/5 of aperture length. Dorsal fold about double of ventral flap, ~1.5-times longer. Pneumostome (pn) ~1/9 of aperture length, bearing air entrance, urinary escape ( Fig. 24 : ua) in left-anterior side ( Fig. 23 : pn), and anus in right-posterior side, separated by transverse fold ( Fig. 23 : an). Lung of 1.5 whorls in length, ~tice longer than wide. Pulmonary vessels conspicuous all along right side ( Fig. 24 ), mostly bearing transverse, rather perpendicular vessels, clustered, sometimes bifurcating or anastomosing; in left side of pulmonary vein (cv), visible vessels only in anterior third, occupying right ~half of this area, constituted by transverse vessels of similar fashion as right side, but inserting in longitudinal vessel ( Fig. 24 : vp), in such anterior end converge with anterior end of pulmonary vessel as part of collar vessel ( Fig. 26 : co). Remaining regions of lung almost smooth, with imbricated vessels of difficult visualization. Pulmonary vein (cv) running longitudinally between middle and right thirds of pallial cavity roof, somewhat equidistant from rectum all along its length. Reno-pericardial area triangular, located posteriorly at middle level of posterior end, occupying ~25% of cavity length and ~70% of its width (details below). Rectum (rt) and ureter (ur) narrow, running along right edge. Urinary aperture very elongated ( Figs. 24 , 13 : ua), occupying ~1/3 of ureter length; its posterior end slightly round- ed, its anterior end just left from anus, T-shaped, being its left branch longer and anteriorly protected by special fold ( Fig. 26 : pn).

Visceral mass: ( Fig. 25 ) ~3.5 whorls in length. Both digestive gland lobes pale greenish beige in color. Anterior lobe (da) flattened,occupying~1/4 of visceral volume,located just posteriorly to pallial cavity, continuous to kidney. Posterior lobe (dg) with 2.5 spiral whorls, with ~45% of visceral volume. Stomach with ~1/8 of visceral volume, located between both digestive gland lobes, about one whorl posterior to pallial cavity (st). Digestive tubes (described below) surrounding anterior lobe of digestive gland. Gonad clearly multi-lobed, greenish-cream color, encased between posterior lobe of digestive gland and columella, occupying ~1/10 of visceral volume.

Circulatory and excretory systems: ( Figs. 13 , 24, 25 ) Pericardium (pc) ~3-times as long as wide, located longitudinally between middle and left thirds of posterior end of pallial roof; occupying ~5% of lung area. Auricle (au) located anteriorly, as continuation from pulmonary vein (cv), slightly larger than ventricle (ve). Kidney (ki) simple, mostly solid, dorso-ventrally flattened; size reported above; somewhat triangular, width ~2/3 of length; inner lobe constituted by longitudinal,tall folds converging anteriorly to middle axis of structure ( Fig. 13 ). Nephropore small, longitudinal slit in anterior-left corner,turned right ( Figs. 24, 25 : ne). Primary and secondary ureter complete and closed (tubular); primary ureter (up) lying on right edge of kidney towards posterior and right, after forming strong curve, running afterwards anteriorly, as secondary ureter (ur) along entire left edge of rectum, except for longitudinal urinary aperture of ~1/3 of its length (ua) (details above).

Digestive system: ( Figs. 25 , 27, 28 ) Arrangement of foregut essentially same as that described for Drymaeus castilhensis ( Simone & Amaral, 2018: 171-172, figs. 41-44) except for: m1v, ventral pair of jugal muscle inserted in middle region of ventral haemocoel surface just posteri- or to buccal mass, running anteriorly, insertion in mouth close to median line; m1a, small pair of lateral jugal muscles, originated in lateral surface of haemocoel, running short distance, inserting in latero-posterior region of buccal mass; m2, pair of retractor muscles of buccal mass slightly narrower and 1.5-times longer; m3, pair of superficial muscles running transversally along postero-lateral surface of buccal mass, from dorso-lateral region to region close to radular nucleus at m2 insertion; m10, pair of ventral protractor muscles of buccal mass slightly thinner and narrower; circular muscles of oral tube (mc) not so developed. Radular sac short, not extending beyond odontophore. Jaw plate ( Fig. 10 : jw) with medial slightly constriction, ~12 pairs of transverse folds medially narrow, gradually becoming wider towards lateral. Radular nucleus inlaid inside odontophore.

Radula ( Figs.14-22 ) as long as odontophore;with rachidi- an teeth,and~55 pairs of lateral teeth;no clear distinction between lateral and marginal teeth ( Figs. 18, 19, 21, 22 ); all teeth with relative long and flattened base, locat- ed closely from neighboring rows; central set of cusps rather small, located in anterior end of base. Rachidian tooth ( Figs. 15, 16, 20 : arrow) small, relatively reduced, ~half of neighboring teeth, ~1/70 of radular width; base ~3-times longer than wide, flattened, barely rectangular; central cusp with ~1/2 of base’s size, tip blunt; pair of basal cusps with ~1/5 of central cusp’s size ( Fig. 16 ). Lateral teeth similar to rachidian,except in being ~twice larger, asymmetrical, arched towards lateral region, cutting edge ~1.5-times larger than that of rachidian; lateral teeth gradually weakly decreasing towards lateral; set of cusps with ~1/2 of length of base; central cusp bluntly pointed; basal cusps strongly asymmetrical, outer basal cusp almost as large as central cusp in more central teeth, almost originating from base ( Fig. 16 ), gradually becoming smaller and sometimes separated from central cusp ( Fig. 15 ); inner cusp ~3-4-times smaller than lateral cusp. Marginal teeth starting with no clear boundary with lateral teeth; shaped similarly to lateral teeth, except for being weakly smaller and with set of cusps broader and slightly less pointed ( Figs. 17-19, 21-22 ); inner basal cusp gradually becoming as large as outer basal cusp and bifid, dividing in two cusps ( Figs. 17, 21, 22 ); teeth becom- ing very narrow in margins ( Fig. 19 ). Each radular row slightly arched disposed from both sides from rachidian ( Fig. 14 ).

Salivary glands covering esophagus in its region preceding its anterior 1/6 ( Fig. 25 : sg), forming two elongat- ed, white, thin masses. Each salivary duct differentiable in anterior side of glands, relatively broad, with ~1/10 esophageal width ( Figs. 25 , 27, 28 : sd). Salivary duct running in both sides of esophageal origin ( Figs. 27, 28 : sd), penetrating buccal mass wall in region close to buccal ganglia ( Fig. 27 : sd), running immersed in buccal dorsal wall along ~1/4 its length ( Fig. 28 : sd). Salivary ducts opening wide, in middle level of dorsal folds, on their middle side ( Fig. 28 : sa).

Esophagus 1 whorl long, with thin, flaccid walls lacking clear subdivisions ( Fig. 25 : es). Stomach ( Fig. 25 : st) relatively narrow, curved, not bulged; position and size described above (visceral mass);gastric walls thin,flaccid; inner surface smooth. Esophageal insertion on posterior side, intestinal origin on anterior side, both close to columella. Duct to anterior lobe of digestive gland located at some distance from stomach, highly branched, covering adjacent intestinal origin and loop ( Fig. 25 : dd-right). Duct to posterior lobe of digestive gland located short distance from esophageal insertion ( Fig. 25 : dd-left). Intestine ~half of width of esophageal insertion, all along its length,including narrow sigmoid loop in anterior lobe of digestive gland ( Fig. 25 : in). Rectum and anus position described above (pallial cavity) ( Fig. 24 : rt, an). Anus sessile, as slit in right end of mantle edge directly turned outside, but still inside pneumostome ( Fig. 23 ); inner surface with 8-10 longitudinal, simple folds ( Fig. 26 : an).

Genital system: ( Figs. 29-34 ) gonad position described above (visceral mass), composed of 4-5 lobes with minute digitiform acini ( Fig. 29 : go). Hermaphroditic duct ( Figs. 29 , 19 : hd) narrow and weakly coiled in both ends, gradually becoming very wider (up to 5-times wider) and more intensely coiled in middle third ( Fig. 29 : hd); inserting in left side of receptacle’s base ( Fig. 32 : hd). Seminal receptacle ( Figs. 29 , 32 : sr) relatively small, sac-like, ~twice longer than wide, with ~twice hermaphroditic duct width. Fertilization complex simple, located at narrow and elongated base of seminal receptacle ( Fig. 32 ) as duct of seminal receptacle; ~as long as length of receptacle. Presence of genital appendix ( Figs. 29 , 32 : ga), as wide as terminal width of hermaphrodite duct, inserted just posterior to it in seminal receptacle’s base; weakly coiled, ~3-times longer than receptacle. Fertilization complex totally immersed in albumen gland ( Fig. 32 ), inserting in posterior end of spermoviduct, in base of albumen gland duct ( Fig. 32 : ad) relatively wide, simple, ~3-times wider than receptacle’s duct. Albumen gland ( Figs. 29 , 32 : ag) solid, white, elliptical, 1.5-times larger than gonad (~1/3 whorl). Albumen gland duct subterminal, connected to distal end of spermoviduct ( Fig. 32 : ad), in lateral, large albumen chamber ( Fig. 32 : ac); widely connected to distal end of spermoviduct. Spermoviduct (eo) of ~1.5 whorl in length, slightly narrower than albumen gland, ca. 20-times longer than wide; intensely coiled and difficulty to rectify. Prostate gland occupy- ing ~1/4 of spermoviduct surface and ~1/5 its volume ( Fig. 33 : pt). Uterus occupying ~3/4 of spermoviduct space, external walls thick-glandular ( Figs. 29, 31 , 32 : ut), inner surface completely covered by ample transverse folds. Sperm grove simple in posterior 2/3 of spermoviduct ( Fig. 33 : sp), protected ventrally by tall fold; abruptly becoming tubular becoming, as vas deferens in anteri- or end of spermoviduct ( Fig. 31 : vd). Free oviduct short, ~1/20 of spermoviduct length, Vagina ~1/10 spermoviduct length ( Figs. 29, 31 : vg); inner surface simple, with 4-5 longitudinal, low, wide folds ( Fig. 31 : vg). Bursa copulatrix ~2/3 of spermoviduct length; bursa duct as wide as adjacent spermoviduct in its origin ( Fig. 31 ), gradually narrowing towards posterior end ( Fig. 29 : bd); bursa oval, ~1/5 of albumen gland size ( Fig. 29 : bc), located encased between pericardium and adjacent intestinal loop. Some specimens with 4-5 elongated, simple spermatophores in bursa duct’s base ( Figs. 11, 12 , 29 : sm). Penis ~1/2 of spermoviduct length, ~2/3 its anterior width ( Fig. 29 : pe); penis muscle inserting terminally,very short ( Fig. 29 : pm). Epiphallus ~1/8 penis’ length, located as short terminal continuation of penis ( Figs. 29 , 34 : eh), inner surface with narrow, irregular longitudinal folds, located close from each other, uniformly sized ( Fig. 34 : eh). Vas deferens inserted subterminally in penis tip ( Figs.29 , 34 : vd). Internal penial surface lacking clear sub-chambers ( Fig. 34 : pe); short smooth middle region posterior region with 5-6 longitudinal, narrow, low folds; anterior region with pair of larger folds ( Fig. 34 ). Penis shield occupying basal ~1/4 of penis length ( Figs. 29, 30 : ps); vas deferens piercing its walls close to its base ( Fig.30 ).Genital pore round,simple.

Central nervous system: ( Figs. 35, 36 ) cerebral ganglia located dorsally in middle level of buccal mass, pedal

ganglia located more posteriorly. Pair of cerebral ganglia (ce) widely fused with each other; cerebral commissure invisible; each ganglion about as wide as adjacent esophageal section ( Fig. 25 : nr); several wide nerves originating in cerebral antero-lateral region. No clear cerebral node or gland.Two pairs of parallel connectives between cerebral ganglia and pedal ganglia. Pair of pedal ganglia (pp) forming single mass located opposite to cerebral ganglia, slightly larger sized than cerebral ganglia. No differentiable individual pedal ganglion detectable.

Distribution: Endemic from Guapirá Island, Currais Archipelago ( Fig. 1 ).

Habitat: The animals were found in a shaded area, inhabiting both the trunks and the abaxial part of the leaves of the tree vegetation of the Ombrophiles Dense Forest that covers the island. They were also located in the bromeliads of the rocky shores that are part of the pioneer rupicolous vegetation.

Measurements: (length and width in mm) Holotype MZSP 150548 ( Figs. 2-4 ): 29.6 by 10.6; paratypes MZSP 135683: #1 ( Figs. 5-6 ), 30.7 by 14.5; #2 ( Figs.7-8 ), 25.2 by 12.7.

Figures

Figure 1.Map of Paraná coastal area,showing the Currais archipelago location and its profile in highlight. Occurrence of specimens in the larger island (eastone).A living crawling specimen also shown (shell length ~20 mm).

Figures2-8. Drymaeuscurrais sp.nov.shell oftypes;(2-4)HolotypeMZSP150548(L29.6),frontal,rightand dorsalview.(5-8)ParatypesMZSP135683.(5-6)Frontal and dorsal view (L 30.7 mm).

Figures 9-13. Drymaeus currais sp. nov. shell and anatomical details.(9) Protoconch of paratype MZSP 135683#3 (young specimen of 14.2 mm), arrow showing transition with teleoconch.Scale =1 mm.(10) Anterior region of mouth,ventral view,integument removed.Scale = 0.5 mm.(11) Duct of bursa sectioned longitudinally,showing4 spermatophoresinside.Scale =1 mm.(12)Isolatedspermatophore.Scale =1 mm.(13)Reno-pericardialarea,ventral view,ventral wallofkidney opened along its left edge and deflected right (upwards) to show inner tissue,ventral pericardial wall deflected left (downwards).Scale = 1 mm.

Figures 14-22. Drymaeus currais sp. nov.radulae in SEM; (14) Holotype,wide view.Scale = 200 µm. (15) Same,higher magnification.Scale = 30 µm. (16) Same, higher magnification. Scale = 20 µm. (17) Detail of lateral region.Scale = 20 µm. (18) Same, lower magnification. Scale = 50 µm. (19) Detail of marginal region. Scale = 50 µm. (20) Paratype MZSP 135683, detail of central region. Scale = 20 µm. (21) Detail of lateral-marginal region, middle region folded.Scale = 50 µm. (22) Same,higher magnification.Scale = 20 µm.Arrows showing rachidian column.

Figures 23-26. Drymaeus currais sp.nov.anatomy;(23) Mantle border as in situ,frontal view.(24) Pallial(pulmonary) cavity,ventral inner view,inner mantle fold deflected upwards. (25) Digestive tubes and some adjacent structures, mainly from visceral mass and posterior region of pulmonary cavity, buccal mass in dorsal view, remaining ventral view, nephrostome (ne) seen by translucency. (26) Anterior-right region of pulmonary cavity, ventral-inner view, inner mantle fold (mf) sectioned and deflectedupwards.Scales = 2 mm.

Figures 27-31. Drymaeus currais sp.nov.anatomy; (27) Foregut, left view. (28) Buccal mass, ventral view, odontophore (od) partially sectioned and deflected to left, right buccal ganglion (bg) and salivary duct (sd) (right in Fig.) insertion seen by translucency.(29) Genital system, dorsal view,partially uncoiled, some spermatophores (sm) seen by translucency.(30) Penis,detail of its proximal region,penis sheath (ps) partially sectioned.(31) Genital ducts,detail of its anterior region, some structures sectioned longitudinally.Scales = 2 mm.

Figures 32-36.Drymaeuscurrais sp.nov.anatomy;(32) Middle region of genital system,ventral view,some structures seen if albumen gland(ag)was transparent. (33) Spermoviduct, transverse section in its middle level. (34) Penis, ventral view, opened longitudinally. (35) Nerve ring, dorsal view. (36) Same, ventral view. Scales = 2 mm.