Parashiela ambulata Laseron 1956
Creators: name: Amati, Bruno
name: Giulio, Andrea Di
name: Oliverio, Marco
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Littorinimorpha
Rissoidae
Parashiela
Parashiela ambulata

description: Parashiela ambulata Laseron, 1956
(Figs 24 A-C; 25; 26; 50; 51B; 53I; Tables 4; 5; 6)
Parashiela ambulata Laseron, 1956: 439, fig. 145.
Parashiela beetsi Ladd, 1966: 64, pl. 12, figs 8, 9.
? Parashiela beetsi – Tröndlé & Boutet 2009: 17.
? Parashiela beetsi – Salvat & Tröndlé 2017: 238.
Parashiela sp. 1 – Boutet et al. 2020: 240.
TYPE MATERIAL. — Parashiela ambulata Laseron, 1956. Holotype. Australia • dd (Fig. 24A, B); Great Barrier Reef, Michaelmas Cay; 16°36’0”S, 145°58’58”E; V.1926; T. Iredale & G. P. Whitley leg., Great Barrier Reef Boring Expedition; AMS-C.102467.
Paratypes. Australia • 10 dd (Fig. 24D, E); Great Barrier Reef, Michaelmas Cay; same data as holotype; AMS-C.109001.
Parashiela beetsi Ladd, 1966. Holotype. Marshall Islands • dd; Eniwetok Atoll, Atomic Energy Commission drill-hole F-8-C; 1952; drill-hole on the atoll, 5.8-6.7 m (19-22 feet); USNM 648368.
Paratype. Marshall Islands • dd; Eniwetok Atoll; same data as holotype; USNM 648369.
TYPE LOCALITY. — Parashiela ambulata. Australia: Queensland, Michaelmas Cay. Parashiela beetsi. Marshall Islands: Eniwetok Atoll.
OTHER MATERIAL EXAMINED. — Australes • 1 dd; Banc Mac Donald, BENTHAUS Stn DW1875; 28°58’58”S, 140°15’0”W; 110-150 m; 4.XI.2002; MNHN • 1 dd; Banc Mac Donald, BENTHAUS Stn DW1877; 28°58’58”S, 140°15’0”W; 59- 150 m; 4.XI.2002; MNHN • 1 dd; Marotiri, BENTHAUS Stn DW1886; 27°51’0”S, 143°31’58”W; 620-1000 m; 6.XI.2002; MNHN • 30 dd; Rapa, Ahurei Bay; 27°36’57”S, 144°19’48”W; 1 m; coll. JL • 1 dd, 1 lv; Rapa, Akatanui Bay, Atelier RAPA Stn 13; 27°36’7”S, 144°18’53”W; 2 m; 8.XI.2002; sandy pockets; MNHN • 1 lv; Rapa, Anarua Ba, Atelier RAPA Stn 72; 27°36’35”S, 144°22’12”W 8; 5-10 m; 25.XI.2002; fine compact sand with algae; MNHN • 15 dd, 38 lv; 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 • 11 lv; 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 lv; Rapa, E of Tupuaki Bay, Atelier RAPA Stn 21; 27°34’12”S, 144°20’34”W; 5 m; 12.XI.2002; slabs of dead corals on sandy bottom; MNHN • 32 dd, 4 lv; 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 • 4 dd; 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 • 34 dd; Rapa, Hiri Bay; 27°37’19”S, 144°22’4”W; 3-5 m; coll. JL • 3 dd, 161 lv; Rapa, Hiri Bay, Atelier RAPA Stn 9; 27°37’19”S, 144°22’12”W; 3-24 m; 6.XI.2002; amidst corals; MNHN • 12 dd, 5 lv; Rapa, N of Anatakuri Bay, Atelier RAPA Stn 38; 27°37’22”S, 144°18’0”W 7; 2 m; 22.XI.2002; sediment under a large rock; MNHN • 5 dd, 24 lv; Rapa, N of Aturapa I., Atelier RAPA Stn 29; 27°34’19”S, 144°20’59”W; 4- 2 m; 15.XI.2002; dead coral; MNHN • 5 lv; Rapa, N of Rapa Iti I., Atelier RAPA Stn 11; 27°37’12”S, 144°18’0”W; 2 m; 7.XI.2002; sandy pockets amidst slabs of dead coral; MNHN • 1 lv; 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 • 92 dd; 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 • 5 dd; 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 • 55 lv; Rapa, off Ahurei Bay, Atelier RAPA Stn 6; 27°36’46”S, 144°16’12”W; 42 m; 5.XI.2002; live and dead corals; MNHN • 76 lv; 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 • 250 dd; 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 • 1 dd; 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 • 175 lv; Rapa, Pointe Kauira, Atelier RAPA Stn 36; 27°33’28”S, 144°20’49”W; 27 m; 21.XI.2002; corals, mostly alive; MNHN • 2 dd, 1 lv; 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 • 77 dd, 44 lv; 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 • 44 lv; Rapa, Pointe Mei, Atelier RAPA Stn 31; 27°38’13”S, 144°18’10”W; 6 m; 16.XI.2002; rocks; MNHN • 54 lv; 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 • 2 dd, 5 lv; Rapa, Pointe Tematapu, Atelier RAPA Stn 2; 27°34.4’S, 144°19.0’W; 29 m; 1.XI.2002; corals, mostly dead; MNHN • 58 lv; Rapa, Pointe Teruametitoi, Atelier RAPA Stn 33; 27°34’47”S, 144°18’36”W; 30 m; 19.XI.2002; dead corals; MNHN • 48 dd; Rapa, Rarapai I., Atelier RAPA Stn 4; 27°34’19”S, 144°22’4”W; 18 m; 4.XI.2002; rocky blocks covered with brown algae; MNHN • 4 dd; 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 • 66 lv; 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 • 12 dd, 1 lv; 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 • 12 dd; 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 • 3 lv; Rapa, SW of Pointe Gotenaonao, Atelier RAPA Stn 27; 27°38’41”S, 144°19’11”W; 6 m; 14.XI.2002; pebble blocks with algae cover; MNHN • 8 dd; 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 • 5 dd, 286 lv; Rapa, Vavai, Atelier RAPA Stn 32; 27°34’58”S, 144°22’40”W; 15-20 m; 18.XI.2002; coral; MNHN • 2 lv; 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 • 30 dd; Rapa, W of Rapa Iti I.; 27°37’15”S, 144°18’3”W; coll. JL • 3 dd; Rapa, W of Rapa Iti I.; 27°37’15”S, 144°18’3”W; 24 m; coll. MB • 44 lv; 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 • 1 dd; Récif Neilson, BENTHAUS Stn DW1914; 27°4’1”S, 146°4’1”W; 150 m; 11.XI.2002; MNHN • 3 dd; Banc Président Thiers, BENTHAUS Stn DW1932; 24°40’58”S, 146°1’58”W; 500-800 m; 14.XI.2002; MNHN • 1 dd; Banc Président Thiers, BENTHAUS Stn DW1933; 24°40’58”S, 146°1’1”W; 500-850 m; 14.XI.2002; MNHN • 94 dd; Raivavae, Motu; 23°53’20”S, 147°37’1”W; 1 m; reef edge; coll. JL • 1 dd; Tubuai, BENTHAUS Stn DW1961; 23°21’0”S, 149°34’1”W; 470-800 m; 19.XI.2002; MNHN • 4 dd; Tubuai, BENTHAUS Stn DW1962; 23°21’0”S, 149°33’0”W; 470-800 m; 19.XI.2002; MNHN • 18 dd; S of Rurutu, BENTHAUS Stn DW2010; 22°31’58”S, 151°20’59”W; 520-950 m; 24.XI.2002; MNHN • 1 dd; North coast of Rurutu BENTHAUS Stn DW 1998; 22°25’1”S, 151°22’1”W; 250- 302 m; 23.XI.2002; MNHN • 2 dd; Rimatara, BENTHAUS Stn DW 2020; 22°37’1”S, 152°49’1”W; 920-930 m; 25.XI.2002; MNHN • 1 dd; Rimatara, BENTHAUS Stn DW2021; 22°37’1”S, 152°49’1”W; 1200-1226 m; 25.XI.2002; MNHN. Tuamotu • 1 dd; Moruroa; 21°46’37”S, 138°53’31”W; beached; on the sea-line; coll. MB • 10 dd; Makemo, Passe Arikitamiro; 16°37’15”S, 143°33’50”W; 20 m, 45 m, 47 m, 54 m; coll. JL • 10 dd; Makemo, Passe Arikitamiro, Nake; 16°37’1”S, 143°33’43”W; <1 m; reef edge; coll. JL • 10 dd; Makemo, Pouheva; 16°37’22”S, 143°35’34”W; reef edge; coll. JL • 10 dd; Katiu; 16°21’50”S, 144°21’21”W; <1 m; reef edge; coll. JL • 10 dd; Raroia; 16°2’9”S, 142°28’37”W; <1 m; reef edge; coll. JL.
Gambier • 5 dd; Mangareva, Rikitea; 23°7’8”S, 134°57’36”W 4; 1 m; coll. JL • 5 dd; Mangareva Taku; 23°5’13”S, 134°58’11”W; 1 m; coll. JL • 4 dd; Gatavake; 23°6’50”S, 134°58’55”W; 1-3 m; coll. JL • 4 dd; Totegegi; 23°5’2”S, 134°52’58”W; 1-3 m; coll. JL • 4 dd; Tenoko; 23°4’26”S, 135°0’35”W; 1-3 m; coll. JL • 4 dd; Taraururoa; 23°6’25”S, 134°51’43”W; 1-3 m; coll. JL.
Society Islands • 18 dd; Tahiti, Arue, Banc du Dolphin; 17°29’49”S, 149°30’3”W; 18-20 m; coll. JL • 18 dd; Tahiti, Arue; 17°31’15”S, 149°31’33”W; 1 m; reef flat behind tomb of King Pomare V; coll. JL • 20 dd; Tahiti, Arue, platier de Vaipoopo; 17°35’41”S, 149°36’50”W; <1 m; coll. JL • 18 dd; Tahiti, Faille d’Arue; 17°31’1”S, 149°31’30”W; 17-48 m; coll. JL • 18 dd; Tahiti, Papeete, Motu Uta; 17°31’51”S, 149°34’51”W; 20 m; wreck, behind breakwater; coll. JL • 18 dd; Tahiti, Tautira; 17°44’27”S, 149°9’46”W; 1-50 m; reef crest; coll. JL • 18 dd; Tahiti, Matavai Bay; 17°31’1”S, 149°30’35”W; 16-25 m, 27 m; coll. JL • 18 dd; Tahiti, Punaauia, La Source; 17°36’7”S, 149°37’15”W; 16 m, 20 m, 30 m; coll. JL • 18 dd; Tahiti, Tiarei; 17°32’34”S, 149°20’27”W; <1 m; reef flat; coll. JL • 18 dd; Tahiti, Paea; 17°41’16”S, 149°35’34”W; 20 m; coll. JL • 18 dd; Tahiti, Mahae 17°33’57”S, 149°19’22”W; <1 m; reef flat; coll. JL • 20 dd; Tahiti, Hitia’a; 17°32’20”S, 149°21’36”W; <1 m; reef edge; coll. JL • 20 dd; Tahiti, Papenoo; 17°30’32”S, 149°25’58”W; <1 m; fringing reef flat; coll. JL • 20 dd; Tahiti, Mahina, Pointe Vénus; 17°29’42”S, 149°29’24”W; 1 m; coll. JL • 4 dd; Tahiti; coll. JL • 1 dd; Tahiti, Papara lagoon; 17°45’28”S, 149°31’22”W; <1 m; coastal reef flat, in coarse sand; coll. MB • 1 dd; Tahiti, Papara lagoon; 17°45’28”S, 149°31’22”W; <1 m; coastal reef flat, in coarse sand; coll. MB • 20 dd; Tetiaroa; 17°1’19”S, 149°36’3”W; 15 m; reef edge; coll. JL • 20 dd; Motu One; 15°48’21”S, 154°30’39”W; 1 m; reef edge; coll. JL.
DISTRIBUTION. — Parashiela ambulata is reported in the Indo-West Pacific from the northern part of Australia to Japan, through the Indian Ocean to the Red Sea (van Gemert 2016: 7). Nearly 2000 specimens of this species have been isolated in the material examined, from the Australes (Banc Mac Donald, Marotiri, Rapa, Récif Neilson, Banc Président Thiers, Tubuai, Rurutu, Rimatara), Tuamotu (Moruroa, Makemo, Katiu, Raroia), Gambier, Society Islands (Tahiti, Tetiaroa, Motu One), with 881 live specimen collected at 2-57 m depth (Fig. 51A).
Parashiela ambulata Laseron, 1956 is sympatric with P. obesula n. sp. in the Australes (Rurutu); with P. expansilabrum n. sp. in the Australes (Rurutu), Tuamotu (Makemo), Society (Tahiti); with P. rimatara n. sp. in the Australes (Rimatara); with P. rotundata n. sp. in the Society (Tahiti) and Tuamotu (Makemo) (Table 5).
DIAGNOSIS. — Parashiela large for the genus, height <2.0 mm, ovate-conic. Protoconch multispiral. Teleoconch with one strong, spiral cordlet, and strong axial ribs extending to the base. Microsculpture of spirally arranged microgranules. Peristome duplicated, almost circular, outer lip orthocline or slightly prosocline, with varix. Non-umbilicate or with narrow fissure. Colouration variable: uniform from white to brown or with spots or bands. For the soft parts see Ponder (1985).
DESCRIPTION (BASED ON POLYNESIAN SPECIMENS)
Shell (Figs 25; 26)
Large for the genus, height 0.85-1.90 mm, height/width ratio 1.53-1.91, rather solid, ovate-conical.
Protoconch (Fig. 25F, G)
Multispiral of 1.30-1.80 whorls, height 0.212 -0.260 mm, nucleus diameter 0.067 -0.087 mm, first half whorl diameter 0.100 - 0.160 mm, maximum diameter 0.237 - 0.280 mm; protoconch I with 5 very thin spiral chains of microgranules, protoconch II with a thin spiral cordlet on the lower third. Protoconch I and II boundary very weak. Protoconch-teleoconch boundary marked, with a sinusigera notch (Fig. 25F).
Teleoconch
Teleoconch of 3.15-3.90 convex whorls with a keel, adapical on the first whorl, then central on the remaining whorls. Axial sculpture on the last whorl of 10-39 thin ribs prosocline, reaching the base and entering the umbilical fissure. Interspaces about twice as wide as the axial ribs. Small rounded tubercles at the intersections. Microsculpture of dense threads, made of fused microgranules (Fig. 25E). Umbilical fissure absent or very narrow. Aperture ovate-piriform height 0.52-0.63 mm, height/aperture height ratio 2.38-2.93, peristome duplicate; outer lip prosocline, slightly sinuous, internally smooth, expanded and strongly thickened, by numerous and appressed growth striae, columellar lip bent medially.
Colour
Uniform white to brown, with or without spiral bands, or spots, or blotches.
Operculum and soft parts
Operculum as for the genus. For the morphology of soft parts see Ponder (1985).
VARIABILITY
Specimens from Polynesia are rather variable, in the colouration (see Fig. 26 A-L), in the number and strength of the axial sculpture (10-39 ribs) (see also Hasegawa 2006b: 109) and in size: minimum adult height 0.85 mm (from Society, Tahiti), maximum 1.90 mm (from Australes, Rapa). Frequently the number and strength of axial ribs vary in different whorls of the same specimen (see Table 4 and Appendix 9).
REMARKS
The type series of 11 specimens (holotype AMS-C.102467 and 10 paratypes AMS-C.109001), includes some not completely adult specimens with faint lip thickening. Laseron (1956: 439), while describing the species, merged features of the holotype with variation in the type series; among the characters of a single specimen (likely the holotype) he gave a height of 1.6 mm, lack of a thick labial varix, and 14 ribs on the body whorl and about 16 on the penultimate whorl, and the original drawing shows a very faint lip thickening; the paratype in Fig. 24D, E has 14 ribs on the body whorl and 16 on the penultimate whorl. We suspect that there might have been an unfortunate swap of specimens and that the specimen currently marked as ‘holotype’ (Fig. 24A, B) 1.8 mm high, with a well thickened lip, is not the one selected by Laseron. This seems to be confirmed by Ladd (1966: 64, pl. 12, figs 8, 9) who diagnosed his Parashiela beetsi from P. ambulata basically due to the different conformation of the lip: double peristome thickened to form a low varix in P. beetsi, simple peristome not thickened in P. ambulata.
It is possible that a complex of species is hidden under the name P. ambulata. This species is reported from a remarkably wide geographic range (from Red Sea to Polynesia: see e.g. Ponder 1985: 51, 153, fig.29, 104A-G; Ekawa 1991: 42, pl. 1, figs 1, 7; 1993: 79, pl. 2, figs 16-17; Hasegawa 2000: 151, pl. 75, fig. 11, two figures; 2006: 109, fig 5A, B; Blatterer & Blatterer 2019: 119, fig. 3a, b). Additionally, we have examined two specimens of Parashiela from Cape Verde (Eastern Atlantic Ocean; coll. Carlo Smriglio, Roma) (Fig. 27A, B) very similar to the types of P. ambulata (Fig. 23 A-E). Criscione et al. (2016) sequenced two specimens morphologically ascribable to P. ambulata, from the Society Islands and Fiji, respectively, with a resulting not negligible genetic divergence. The numerous specimens examined by us from the Australes, Tuamotu, Gambier and Society, are not morphologically separable from P. ambulata Laseron, 1956, but also showed a remarkable variability. We therefore use Parashiela ambulata for the Polynesian material, conservatively, pending additional comparative studies, ideally including genetic data.
See under P. expansilabrum n. sp. and P. rimatara n. sp. for detailed comparisons.
description: Published as part of Amati, Bruno, Giulio, Andrea Di & Oliverio, Marco, 2023, Shallow-water Rissoidae of the genera Alvania Risso 1826 Haurakia Iredale 1915 Parashiela Laseron 1956 Simulamerelina Ponder 1985 and Subestea Cotton 1944 Gastropoda Caenogastropoda Rissooidea from French Polynesia with the description of a new deep-water genus, pp. 803-892 in Zoosystema 45 (25) on pages 837-843, DOI: 10.5252/zoosystema2023v45a25, http://zenodo.org/record/10458066