Alvania herosae n. sp.

(Figs 7; 8; 9; 10; 11; 12; 13; 49A; 53B, C; Tables 1; 2)

urn:lsid:zoobank.org:act: B6F4656A-8D02-4150-9DBD-0CB4BEEB55BB

Alvania sp. 2 – Boutet et al. 2020: 239.

TYPE MATERIAL. — Holotype. Australes • dd (height 2.02 mm, width 1.10 mm, Figs 7; 9B; 53B); Rapa, East of Tupuaki Bay, Atelier RAPA Stn 21; 27°34’12”S, 144°20’34”W; 5 m; 12.XI.2002; blocks of dead coral on a sandy bottom; MNHN-IM-2000-38704 .

Paratypes. Australes • 116 dd (morph A), 17 lv (morph A); same locality data as holotype; MNHN-IM-2000-38705.

TYPE LOCALITY. — Australes. Rapa, East of Tupuaki Bay, Stn 21; 27°34’12”S, 144°20’34”W; 5 m; blocks of dead coral on a sandy bottom, Atelier RAPA 12.XI.2002.

OTHER MATERIAL EXAMINED. — Australes • 129 dd (morph A); Marotiri, BENTHAUS Stn DW1885; 27°52’1”S, 143°33’0”W; 700-800 m; 6.XI.2002; MNHN • 7 dd (morph A); Marotiri, BENTHAUS Stn DW1886; 27°51’0”S, 143°31’58”W; 620-1000 m; 6.XI.2002; MNHN • 40 dd (morph A), 13 dd (morph B); E of Rapa, BENTHAUS Stn DW1889; 27°37’1”S, 144°16’1”W; 600- 620 m; 7.XI.2002; MNHN • 1 dd (morph B); Rapa; 27°36’57”S, 144°19’48”W; coll. MB • 41 dd (morph A); Rapa, Ahurei Bay; 27°36’57”S, 144°19’48”W; 1 m; coll. JL • 4 dd (morph A), 2 dd (morph B); Rapa, Ahurei Bay; 27°36’57”S, 144°19’48”W; 1 m; coll. MB • 15 dd (morph A); Rapa, Ahurei Bay, Atelier RAPA Stn 77; 27°37’12”S, 144°19’48”W; intertidal; 5.XI.2002; near wharf; MNHN • 8 dd (morph A), 22 dd (morph B); Rapa, Akatamiro Bay, Atelier RAPA Stn 94; 27°34’37”S, 144°21’25”W; intertidal; 5.XII.2002; MNHN • 31 dd (morph A), 1 lv (morph A), 7 dd (morph B); Rapa, Akatanui Bay, Atelier RAPA Stn 13; 27°36’7”S, 144°18’53”W; 2 m; 8.XI.2002; sandy pockets; MNHN • 1 dd (morph B); Rapa, Akatanui Bay, Atelier RAPA Stn 81; 27°35’52”S, 144°18’28”W; intertidal; 9.XI.2002; rocks; MNHN • 71 dd (morph A), 8 dd (morph B); Rapa, Anarua Bay, Atelier RAPA Stn 41; 27°36’18”S, 144°22’40”W; 5 m; 25.XI.2002; corals on sandy bottom; MNHN • 4 dd (morph A), 4 dd (morph B); Rapa, Anarua Bay, Atelier RAPA Stn 87; 27°36’25”S, 144°22’37”W; intertidal; 25.XI.2002; entry of cave; MNHN • 2 dd (morph A), 10 dd (morph B); Rapa, Anatakuri Bay, Atelier RAPA Stn 69; 27°37’47”S, 144°18’43”W; 3-4 m; 19.XI.2002; coarse sand and algae; MNHN • 1 dd (morph A), 14 dd (morph B); Rapa, Anatakuri Nako Bay, Atelier RAPA Stn 25; 27°38’24”S, 144°18’53”W; 3 m; 13.XI.2002; blocks of dead coral on sand; MNHN • 2 dd (morph A), 1 dd (morph B), 1 dd (intermediate form); Rapa, Anatakuri Nako Bay, Atelier RAPA Stn 64; 27°38’24”S, 144°18’53”W; 1.5-2 m; 16.XI.2002; fine muddy sand; MNHN • 5 dd (morph A); Rapa, E of Area, Atelier RAPA Stn 54; 27°36’35”S, 144°19’19”W; 12-20 m; 5.XI.2002; yellow mud, corals on the slopes; MNHN • 9 dd (morph A); Rapa, Haurei Bay, Atelier RAPA Stn 43; 27°36’46”S, 144°18’18”W; 45 m; 26.XI.2002; muddy bottom at the foot base of a drop-off; MNHN • 23 dd (morph A); Rapa, Haurei Bay, Atelier RAPA Stn 47; 27°36’43”S, 144°19’4”W; 33 m; 29.XI.2002; corals on muddy bottom; MNHN • 232 dd (morph A); Rapa, Hiri Bay; 27°37’19”S, 144°22’4”W; 3-5 m; coll. JL • 2 dd (morph A); Rapa, Hiri Bay; 27°37’19”S, 144°22’4”W; 3-5 m; coll. MB • 60 dd (morph A), 1 lv (morph A), 10 dd (morph B); Rapa, Hiri Bay, Atelier RAPA Stn 9; 27°37’19”S, 144°22’12”W; 3-24 m; 6.XI.2002; amidst corals; MNHN • 31 dd (morph A), 27 lv (morph A), 57 dd (morph B), 14 lv (morph B); Rapa, N of Anatakuri Bay, Atelier RAPA Stn 38; 27°37’22”S, 144°18’25”W; 2 m; 22.XI.2002; sediment under a large rock; MNHN • 104 dd (morph A), 105 lv (morph A), 37 dd (morph B); Rapa, N of Aturapa I., Atelier RAPA Stn 29; 27°34’19”S, 144°20’59”W; 2-4 m; 15.XI.2002; dead coral; MNHN • 102 dd (morph A); Rapa, N of Rapa Iti I., Atelier RAPA Stn 11; 27°37’12”S, 144°18’10”W; 2 m; 7.XI.2002; sandy pockets amidst slabs of dead coral; MNHN • 39 dd (morph A), 22 dd (morph B); Rapa, Nord of Pukitarava, Atelier RAPA Stn 14; 27°35’49”S, 144°13’37”W; 2 m; 8.XI.2002; dead coral blocks on sand; MNHN • 14 dd (morph A); Rapa, NW of Tauna I., Atelier RAPA Stn 44; 27°36’18”S, 144°18’10”W; 30 m; 27.XI.2002; drop-off with muddy bottoms; MNHN • 146 dd (morph A); Rapa, off Ahurei Bay, Atelier RAPA Stn 6; 27°36’46”S, 144°16’40”W; 42 m; 5.XI.2002; live and dead corals; MNHN • 102 dd (morph A), 5 dd (morph B); Rapa, off Cape Rukuaga, Atelier RAPA Stn 22; 27°33’54”S, 144°21’43”W; 18-22 m; 13.XI.2002; corals on rocky bottom; MNHN • 133 dd (morph A), 2 dd (morph B); Rapa, off Pointe Rukuaga, Atelier RAPA Stn 48; 27°34’4”S, 144°22’4”W; 36 m; 30.XI.2002; plateau with silty sand; MNHN • 85 dd (morph A), 5 dd (morph B); Rapa, Pake Bay, Atelier RAPA Stn 61; 27°37’1”S, 144°18’36”W; 10-15 m; 11-14.XI.2002; sandy mud and coral; MNHN • 7 dd (morph A), 20 dd (morph B); Rapa, Pariati Bay, Atelier Rapa Stn 67; 27°34’40”S, 144°21’43”W; 3-4 m; 18.XI.2002; muddy sand and seaweed; MNHN • 167 dd (morph A), 15 lv (morph A); Rapa, Pointe Kauira, Atelier RAPA Stn 36; 27°33’28”S, 144°20’49”W; 27 m; 21.XI.2002; corals, mostly alive; MNHN • 4 dd (morph A), 1 dd (morph B); Rapa, Pointe Komiré, Atelier RAPA Stn 10; 27°34’47”S, 144°22’47”W; 16-18 m; 7.XI.2002; rocks covered with brown algae; MNHN • 291 dd (morph A), 53 lv (morph A); Rapa, Pointe Mei, Atelier RAPA Stn 30; 27°38’13”S, 144°18’10”W; 16-20 m; 16-18. XI.2002; drop-off with dead corals; MNHN • 565 dd (morph A), 3 lv (morph A), 4 dd (morph B); Rapa, Pointe Mei, Atelier RAPA Stn 31; 27°38’13”S, 144°18’10”W; 6 m; 16.XI.2002; rocks; MNHN (1 coated for SEM) • 56 dd (morph A), 11 dd (morph B); Rapa, Pointe Taekateke, Atelier RAPA Stn 28; 27°38’24”S, 144°20’34”W; 30 m; 15.XI.2002; rocky blocks with algal cover; MNHN • 36 dd (morph A); Rapa, Pointe Teruametitoi, Atelier RAPA Stn 33; 27°34’47”S, 144°18’36”W; 30 m; 19.XI.2002; dead corals; MNHN • 3 dd (morph B); Rapa, Rapa Iti, Atelier RAPA Stn 83; 27°37’19”S, 144°18’7”W; intertidal; 12-13.XI.2002; MNHN • 23 dd (morph A); Rapa, Rarapai I., Atelier RAPA Stn 4; 27°34’19”S, 144°21’36”W 8; 18 m; 4.XI.2002; rocky blocks covered with brown algae; MNHN • 72 dd (morph A), 13 dd (morph B); Rapa, S of Anatakuri Bay, Atelier RAPA Stn 19; 27°37’40”S, 144°18’43”W; 3 m; 11.XI.2002; coral blocks on sandy bottom; MNHN • 88 dd (morph A), 12 dd (morph B); Rapa, S of Tarakoi I., Atelier RAPA Stn 5; 27°5’34”S, 144°18’28”W; 8 m; 4.XI.2002; dead corals with algae, muddy-sandy pockets; MNHN • 2 dd (morph A); Rapa, SE of Pointe Tematapu, Atelier RAPA Stn 34; 27°34’47”S, 144°19’1”W; 2-8 m; 19.XI.2002; slope in a large cave, muddy bottom; MNHN • 60 dd (morph A), 7 lv (morph A), 5 dd (morph B), 2 lv (morph B); Rapa, SE of Pointe Tematapu, Atelier RAPA Stn 35; 27°34’47”S, 144°19’1”W; 2 m; 20.XI.2002; pebbles at cave exit; MNHN • 7 dd (morph A); Rapa, SE of Tauna I., Atelier RAPA Stn 8; 27°36’28”S, 144°17’41”W; 52-57 m; 06-22.XI.2002; rocky bottoms with sandy pockets; MNHN • 1 dd (morph A), 4 dd (morph B); Rapa, SW of Pointe Gotenaonao, Atelier RAPA Stn 27; 27°38’41”S, 144°19’11”W; 6 m; 14.XI.2002; rocks with algae cover; MNHN • 3 dd (morph A), 3 dd (morph B); Rapa, SW of Rarapai I., Atelier RAPA Stn 17; 27°34’37”S, 144°22’40”W; 9 m; 10.XI.2002; rocky boulders on sandy bottom; MNHN • 51 dd (morph B); Rapa, Vavai, Atelier RAPA Stn 20; 27°35’23”S, 144°23’16”W; 5 m; 12.XI.2002; coral blocks on sand bottom; MNHN • 470 dd (morph A), 3 lv (morph A), 22 dd (morph B); Rapa, Vavai, Atelier RAPA Stn 32; 27°34’58”S, 144°22’40”W; 15-20 m; 18.XI.2002; coral; MNHN • 1 dd (morph B); Rapa, W of Pointe Aukura, Atelier RAPA Stn 15; 27°38’6”S, 144°21’7”W; 20 m; 9.XI.2002; sandy pockets amidst large rocky blocks; MNHN • 85 dd (morph A), 90 dd (morph B); Rapa, W of Rapa Iti I.; 27°37’15”S, 144°18’3”W; 24 m; coll. JL • 61 dd (morph A), 1 dd (morph B); Rapa, W of Tauna I., Atelier RAPA Stn 16; 27°36’18”S, 144°18’25”W; 5 m; 9.XI.2002; corals, mostly dead; MNHN • 2 dd (morph A); Rapa, wharf of Area, Atelier RAPA Stn 70; 27°36’35”S, 144°19’11”W 5; 15-20 m; 20.XI.2002; muddy pockets and corals; MNHN • 4 dd (morph A); Récif Neilson, BENTHAUS Stn DW1914; 27°4’1”S, 146°4’1”W; 150 m; 11. XI.2002; MNHN • 1 dd (morph A); Récif Neilson, BENTHAUS Stn DW1924; 27°1’1”S, 146°4’58”W; 340-800 m; 12.XI.2002; MNHN • 1 dd (morph A); Banc Président Thiers, BENTHAUS Stn DW1927; 24°38’59”S, 146°1’37”W; 105- 95 m; 13.XI.2002; MNHN • 13 dd (morph A); Banc Président Thiers, BENTHAUS Stn DW1932; 24°40’58”S, 146°1’58”W; 500-800 m; 14.XI.2002; MNHN • 10 dd (morph A); Banc Président Thiers, BENTHAUS Stn DW1933; 24°40’58”S, 146°1’1”W; 500-850 m; 14.XI.2002; MNHN • 3 dd (morph A); Banc Président Thiers, BENTHAUS Stn DW1937; 24°40’1”S, 145°55’58”W; 469-500 m; 14.XI.2002; MNHN • 5 dd (morph A); Raivavae; 23°51’0”S, 147°38’34”W; from reef flat (1 m) to 20 m; coll. JL • 11 dd (morph A); Tubuai; 23°20’38”S, 149°28’33”W; beached; coll. MB • 9 dd (morph A); Tubuai, BENTHAUS Stn DW1962; 23°21’0”S, 149°33’0”W; 470- 800 m; 19.XI.2002; MNHN • 36 dd (morph A); Tubuai, Mataura; 23°22’4”S, 149°32’2”W; 1 m; coll. JL • 11 dd (morph A); Tubuai, Mataura; 23°22’1”S, 149°31’40”W; beached; coll. MB • 2 dd (morph A); Banc Arago, BENTHAUS Stn DW1975; 23°23’59”S, 150°43’58”W; 600-691 m; 20.XI.2002; MNHN • 3 dd (morph A), 1 dd (morph B); E coast of Rurutu, BENTHAUS Stn DW 2003; 22°28’1”S, 151°18’36”W 7; 250-330 m; 24.XI.2002; MNHN • 20 dd (morph A); Rurutu, Vitaria; 22°28’44”S, 151°21’14”W; 1 m; fringing reef platform of Vitaria; coll. JL • 18 dd (morph A); Rurutu, Morerai; 22°26’56”S, 151°20’9”W; 51 m; coll. JL • 19 dd (morph A); S of Rurutu BENTHAUS Stn DW2010; 22°31’58”S, 151°20’59”W; 520-950 m; 24.XI.2002; MNHN • 15 dd (morph A); Rimatara; 22°38’45”S, 152°47’23”W; 1 m; reef flat; coll. JL • 115 dd (morph A); Rimatara, BENTHAUS Stn DW 2020; 22°37’1”S, 152°49’1”W; 920-930 m; 25.XI.2002; MNHN • 39 dd (A, 7 of which large size); Rimatara, BENTHAUS Stn DW2021; 22°37’1”S, 152°49’1”W; 1200-1226 m; 25.XI.2002; MNHN.

Gambier • 6 dd (morph A); Mangareva, Rikitea; 23°6’39”S, 134°58’1”W; beached; coll. JL.

DISTRIBUTION AND SYMPATRY. — Alvania herosae n. sp. is known from the South Pacific Ocean, in the Australes chain (Marotiri, Rapa, Récif Neilson, Banc Président Thiers, Raivavae, Tubuai, Banc Arago, Rurutu, Rimatara) and Gambier with 203 live specimens collected in 2-24 m depth (Fig. 49A).

Empty but fresh shells are usually collected from 0 to 57 m depth; shells from deeper samples (95-1226 m depth), usually in bad conditions, are probably drifted down from upper bottoms.

Alvania herosae n. sp. is sympatric in the Australes (Rapa) with Alvania prosocostata n. sp. and Alvania uapou n. sp.; in the Gambier with Alvania prosocostata n. sp. (Table 2).

ETYMOLOGY. — Named after Virginie Héros (MNHN, Paris), who participated in the Atelier RAPA expedition, for her indefatigable, long lasting, and always graciously helpful work on the MNHN collections.

DIAGNOSIS. — Alvania small for the genus (height c. 2 mm), with rather robust shell; protoconch paucispiral; teleoconch morphologically very variable; at least two extreme morphotypes observed (morph A and morph B), with rare intermediate forms. Colouration very variable: uniform, banded or with coloured blotches.

DESCRIPTION OF HOLOTYPE

Shell (Figs 7; 9B; 53B)

Small for the genus, height 2.02 mm, width 1.10 mm, height/ width ratio 1.84, ovate-conical.

Protoconch (Fig. 7D, E)

Paucispiral, of 1.25 whorls, height 0.225 mm, nucleus diameter 0.112 mm, first half whorl diameter 0.200 mm, maximum diameter 0.300 mm; sculptured by microtubercles, many fused and spirally arranged, well separated on the nucleus and just before the protoconch/teleoconch boundary (Fig. 7D, E). Protoconch-teleoconch boundary well marked (Fig. 7D, E).

Teleoconch

Of 3.75 convex whorls, with suture impressed, little canaliculated. Axial sculpture on the last whorl of 18 orthocline ribs in the upper whorls, slightly prosocline on the last, thinner than interspaces, gradually vanishing at the base. Spiral sculpture finer than axial, of equidistant cordlets, 9 on last whorl, 5 above the aperture and 4 on the base.

Cord III and V starting immediately after the protoconch-teleoconch boundary; immediately afterwards cords I and II developing almost simultaneously, cord II formed subsequently. On the last lap 5 equidistant cords of same size.

Small, rounded tubercles at the intersections of the sculptures. Microsculpture of spiral microstriae on the entire surface, crossing the growth lines (Fig. 7D, E). Umbilical fissure absent. Aperture piriform, height 0.8 mm, height/aperture height ratio 2.53, peristome continuous, outer varix large, sharp lip, internally smooth, slightly prosocline.

Colour

Colouration of teleoconch yellowish-white with quadrangular spots arranged on the spiral cordlets; some light brown spots scattered on the teleoconch, inner lip with some lighter spots. Columellar area brownish; a darker subsutural spot on the outer lip.

Operculum and soft parts

Operculum typical for the genus, width 0.425 mm, length 0.625 mm in a specimen 1.75 mm high.

Soft parts unknown.

VARIABILITY

Two morphotypes are present named here ‘A’ and ‘B’, which we provisionally and conservatively regard as representing a single very variable species, because intermediates have been observed (Fig. 9), although very rarely. We have selected as holotype a specimen of morph ‘A’ (as well as all paratypes). The extreme specimens of the two morphs differ rather consistently in the strength and different genesis of the spiral cordlets.

In morph ‘A’ (corresponding to the holotype), all cordlets are of the same strength; cordlets III and V appear immediately after the protoconch-teleoconch boundary; then, the remaining cordlets (I, II, IV).

In morph ‘B’, cordlets III and IV appear immediately after the protoconch-teleoconch boundary and are stronger than the rest; subsequently and gradually, the smaller cordlets I and II are formed. Less frequently cordlets III and V appear immediately after the protoconch-teleoconch boundary; subsequently cordlets I, II and IV appear.

Variation in morph ‘A’ includes:

Rare specimens from Rimatara (see Figs 10; 12; Table 1), have 3 cordlets starting after the protoconch-teleoconch boundary (I, III, V), subsequently followed by cordlets II and IV. A single specimen from Rimatara (Fig. 11) has 4 cordlets (I, III, V, VII) starting after the protoconch-teleoconch boundary, subsequently followed by cordlets II, IV and VI. Not infrequently the suprasutural cordlet is more protruding than the others (Fig. 13C, E). The axial ribs can be more obsolete, making the spiral sculpture more evident (Fig. 13H). Number and strength of the teeth inside the outer lip vary in proportion to the number of spiral cordlets on the last whorl. Maximum adult height 3.05 mm, minimum 1.05 mm. The protoconch is also variable in the aggregation of the tubercles (Figs 7D, E; 8D, E; 10D; 11C, D; 12D, E). Colouration very variable: uniform white, brown, orange or with a whitish, yellowish or light brown background and a series of more or less large whitish spots or blotches; whitish-yellowish background with two darker bands, subsutural and basal, always with a brownish columellar area; pale yellow background with reddish spiral cordlets; white with short spiral lines on the reddish cordlets; brown with the first whorls white; white with subsutural quadrangular blotches.

Variation in morph ‘B’ includes:

Maximum height 2.5 mm; minimum height 1.6 mm. The colouration is also variable: uniform white or brown, or uniform yellowish with brownish columellar zone, whitish-yellowish background with two darker bands, subsutural and basal, always with brownish columellar zone; light brownish with white tubercles (See Table 1 and Appendices 2; 3).

REMARKS

The species is characterized by an extreme variability in the sculptures (number and strength of the elements) and in the colouration (see Variability; Figs 9; 13 and Table 1).

The morph ‘A’ of A. herosae n. sp. recalls the drawing and, in part, the original description of Alvania denseclathrata (Thiele, 1925) n. comb. from southern Africa in 80 m (Thiele 1925: 81, pl. 6, fig. 11) (here Fig. 11A, B and Fig. 2G). Specimens of the type series of Rissoa denseclathrata Thiele, 1925 (lectotype and nine paralectotypes ZMB/Ma.64984) (Fig. 2 A-G) have a similar paucispiral protoconch, sculptured by microtubercles, and are of the same size (height c. 2 mm) with a dense axial and spiral sculpture. However, A. denseclathrata n. comb. differs from A. herosae n. sp. in its thinner and more flexuose axial ribs; more numerous spiral cordlets on the last whorl (16 vs 8-12 in Alvania herosae n. sp.); whitish vs highly variable colour in Alvania herosae n. sp.; hint of umbilical fissure, absent in Alvania herosae n. sp.; absence of tubercles at the intersection of the sculpture.

Alvania albachiarae Perugia, 2021, from Masirah Island (Oman) (Perugia 2021: 1, 6, pl. 1, fig. D-F), differs from Alvania herosae n. sp. in its axial ribs reaching the base and forming evident tubercles at the intersection with all the spirals vs axial ribs interrupted before the base leaving smooth spiral on the base in Alvania herosae n. sp.

The morph ‘B’ of A. herosae n. sp. recalls the drawing and, in part, the original description of Alvania proditoris (Thiele, 1925) n. comb. from Agulhas Bank, South Africa (Thiele 1925: 46, pl. 6, fig. 9) (here Fig. 8 A-C and Fig. 3G). Specimens of the type series of Rissoa proditoris Thiele, 1925 (lectotype and nine paralectotypes, ZMB/Moll. n. 64965) (Fig. 3 A-G) have a protoconch with 9 spiral cordlets vs scattered tubercles in Alvania herosae n. sp.; orthocline vs prosocline outer lip; two major spiral cordlets, and one much thinner subsutural cordlet on the last whorl vs two main cordlets and two additional thinner subsutural cordlets In A. herosae n. sp.

Alvania lusoria (Yokoyama, 1926), from the Pliocene of Sado Island, Japan (Yokoyama 1926: 273, pl. 33, fig.18), differs from A. herosae n. sp. in its less protruding first protoconch whorl; in the smaller and strongly prosocline aperture, only slightly prosocline in A. herosae n. sp.; in the fewer spiral cordlets on the last whorl (6 vs 7-10 in A. herosae n. sp. morph ‘B’); in the non-varicose vs varicose outer lip.