Halongella schlumbergeri (Morlet, 1886a)

Pall-Gergely, Barna, Hunyadi, Andras, Ablett, Jonathan, Lương, Hao Văn, Fred Naggs, & Asami, Takahiro, 2015, Systematics of the family Plectopylidae in Vietnam with additional information on Chinese taxa (Gastropoda, Pulmonata, Stylommatophora), ZooKeys 473, pp. 1-118 : 48-62

Taxon classification Animalia Stylommatophora Plectopylidae

Halongella schlumbergeri (Morlet, 1886a) Figures 6 A–D, 9 M–N, 14 H–N, 26, 29 A–B, 29H, 30 G–I, 33 A–G, 36 D–F, 45B

Helix (Plectopylis) Schlumbergeri Morlet 1886a, Journal de Conchyliologie, 34: 259, 272-274., Plate 12., Figs 2 a–c. ["Baie d’Along et montagne de l’Éléphant”].

Helix (Plectopylis) Schlumbergeri Morlet 1886b, Diagnoses de mollusques terrestres et fluviatiles du Tonkin. 1-2.

Plectopylis Schlumbergeri , - Mabille 1887b, Bulletin de le Société Malacologique de France, 4: 101-102.

Plectopylis jovia Mabille 1887b, syn. n., Bulletin de le Société Malacologique de France, 4: 99-100. ["Circa locum dictum Halong"].

Helix schlumbergeri , - Tryon 1887, Manual of Conchology. 2 (3): 166, Plate 36., Figs 25-28.

Plectopylis Schlumbergeri , - Ancey 1888, Le Naturaliste, 2(10): 72.

Plectopylis jovia , - Pilsbry 1893, Manual of Conchology..., 2 (8): 156-157.

Plectopylis villedaryi , - Pilsbry 1893, Manual of Conchology..., 2 (8): 158., Plate 43., Figs 36-39.

Plectopylis jovia , - Pilsbry 1894, Manual of Conchology...: 146., Plate 40., Figs 1-4.

Plectopylis schlumbergeri , - Gude 1897b, Science Gossip, 4: 138., Figs 58 a–b. ["Halong Bay and Elephant Mountain, Tonkin"].

Plectopylis jovia , - Gude 1897b, Science Gossip, 4: 138-139., Figs 59 a–b. [ “Halong”].

Plectopylis schlumbergeri , - Gude 1899a, Science Gossip, 5: 332.

Plectopylis jovia , - Gude 1899a, Science Gossip, 5: 332.

Plectopylis (Endoplon) schlumbergeri , - Gude 1899c, Science Gossip, 4: 148.

Plectopylis (Endoplon) jovia , - Gude 1899c, Science Gossip, 4: 148.

Plectopylis (Endoplon) schlumbergeri , - Gude 1899d, Science Gossip, 6: 175.

Plectopylis (Endoplon) jovia , - Gude 1899d, Science Gossip, 6: 175.

Plectopylis (Endoplon) hirsuta Möllendorff 1901, syn. n., Nachrichtsblatt der Deutschen Malakozoologischen Gesellschaft, 33 (5/6): 114-115. ["in insula Bah-mun"].

Plectopylis Schlumbergeri , - Gude 1901a, Journal de Conchyliologie, 49: 199.

Plectopylis Villedaryi , - Gude 1901a, Journal de Conchyliologie, 49: 212. ["Llots de la baie d’Along”].

Plectopylis jovia , - Gude 1901b, Journal of Malacology, 8: 47-48., Figs 1 a–b.

Plectopylis schlumbergeri , - Gude 1901b, Journal of Malacology, 8: 47-48., Figs 2 a–b.

Plectopylis villedaryi , - Gude 1901b, Journal of Malacology, 8: 47-48., Figs 3 a–b.

Plectopylis pilsbryana Gude 1901c, syn. n., Journal of Malacology, 8: 110., ["Lang-Son, Bac-Ninh (Vathelet). Isles in Along Bay (Messager). Tonkin (Fruhstorfer)"].

Plectopylis (Endoplon) hirsuta , - Gude 1901c, Journal of Malacology, 8: 111-112., Figs 1 a–f. ["Island Bah-Mung"].

Plectopylis (Endoplon) jovia , - Gude 1901c, Journal of Malacology, 8: 111-112., Figs 1 a–f.

Plectopylis Schlumbergeri , - Dautzenberg & Fischer 1905a, Journal de Conchyliologie, 53: 93.

Plectopylis jovia , - Dautzenberg & Fischer 1905a, Journal de Conchyliologie, 53: 93.

Plectopylis Villedaryi , - Dautzenberg & Fischer 1905a, Journal de Conchyliologie, 53: 93.

Gudeodiscus schlumbergeri , - Páll-Gergely & Hunyadi 2013, Archiv für Molluskenkunde 142 (1): 8.

Gudeodiscus pilsbryana , - Páll-Gergely & Hunyadi 2013, Archiv für Molluskenkunde, 142 (1): 8.

Gudeodiscus jovius , - Páll-Gergely & Hunyadi 2013, Archiv für Molluskenkunde, 142 (1): 8.

Gudeodiscus hirsutus , - Páll-Gergely & Hunyadi 2013, Archiv für Molluskenkunde, 142 (1): 8.

Types examined.

Llots de la Baie d’Along, leg. Messager (n. 23.), MNHN IM-2010-12119. (cited in Journal de Conchyliologie, 49: 212. as villedaryi ); Tonkin, Halong, leg. l’Abbé Vathelet, MNHN 24580 (one adult and one juvenile syntypes of jovia , Figure 6B); Tonkin, NHMUK 1922.8.29.52 (holotype of pilsbryana , Figure 6C); Tonkin, MNHN 24582 (2 syntypes of schlumbergeri , Figure 6A); Tonkin, Bah-Mun, coll. Möllendorff ex Fruhstorfer, SMF 9277 (lectotype of hirsuta , Figure 6D); same data, SMF 9278 (2 paralectotypes of hirsuta ).

Museum material examined.

Tonkin, That-Khé, coll. Dosch ex Rolle ex Messager, SMF 341737/2; Tonkin, ex Fruhstorfer, SMF 150132/2; Tonkin, Tafel Insel, ex Fruhstorfer, H. 126, SMF 150131/2; Tonkin, Isle de la Table, coll. Ehrmann ex Webb, W. F., SMF 150130/3; Tonkin, Isle de la Table, coll. Ehrmann ex Webb, W. F., SMF 150124/1; Tonkin, coll. Ehrmann ex Fruhstorfer, H., SMF 150123/1; Tonkin, rochers de Kuy-Dong-Kay, coll. Jaeckel, S. H., SMF 207677/2; Tonkin, Isle de la Table, SMF 207678/1; Tonkin, rochers de Nuy-Dong-Nay, coll. Schlickum 3969 ex Staid (?), SMF 277560/2; Tonkin, Than-Moi, coll. Jaeckel, S. H., SMF 207670/4; Tonkin, rochers de Nuy-Dong-Nuy, coll. Pfeiffer, K. L. ex Sundler, October 1940, SMF 102825/2; Tonkin, Ile de la Table, Baie d’Along, SMF 294868/2; Tonkin, coll. Dosch ex Rolle, SMF 172096/2; Tonkin, Ile de la Table, coll. Dosch ex Rolle ex Webb, SMF 172094/2; Tonkin, Ile des Merveilles, coll. Möllendorff ex Fruhstorfer 130, SMF 150129/2; Tonkin, Hai-fong, coll. Möllendorff ex Fruhstrofer, SMF 150128/1; Hongay, leg. Drimmer, 09.11.1986. ex Kovács, Gy., HNHM 67079/2; Hongay, leg. Drimmer, 09.11.1986., HNHM 78324/4; Nuy Dong Nay, leg. Drimmer, HNHM 67068/1; Tonkin: Roches de Nuy-Dong-Nay HNHM 37877/2; Tonkin, coll. Mansuy, MNHN-IM-2012-2260/4; Tonkin, coll. Sayer 1969, MNHN-IM-2012-2261/1; Tonkin, leg. abbe Wathelet, MNHN-IM-2012-2262/3; Baie d’Along, Ile de le Table, coll. Lavezzari ex Bernays, MNHN-IM-2012-2264/3; Tonkin, coll. Balansa 1887, MNHN-IM-2012-2269/4; Baie d’Halong, excoll. labo. de Géologie de la Sorbonne ( entrée 1952), MNHN-IM-2012-2271/2; Baie d’Halong, coll. Staadt, 1969, MNHN-IM-2012-2280/1 juvenile shell; Baie d’Along, Ile de la Table, MNHN-IM-2012-2289/3; Tonkin, coll. Staadt 1969, MNHN- IM- 2012-2291/24; Tonkin, coll. Balansa 1887, MNHN-IM-2012-2294/4; Halong, MNHN-IM-2012-2295/2; Grotte des Merveilles, coll. Saurin, MNHN-IM-2012-2299/7; Tonkin, coll. Letellier, 1949, MNHN-IM-2012-2304/1; Halong Bay, leg. Messager, MNHN-IM-2012-2316/1; Halong Bay, leg. Messager, MNHN-IM-2012-2317/4; Halong Bay, leg. Messager, MNHN-IM-2012-2322/4; No locality, leg. V. Demange, 29.01.1931, coll. Staadt, 1969, MNHN-IM-2012-2329/298; Tonkin, coll. Denis, MNHN-IM-2012-2332/6; Rochers de Nuy-Dong-Nay, MNHN-IM-2012-2481/529; Tonkin, coll. Staadt. 1969, MNHN-IM-2012-2444/366; Dong-Trien, coll. Blaise, 1902, MNHN-IM-2012-2347/1; Dong-Trien, coll. Blaise, 1903, MNHN-IM-2012-2348/1; Ile de la Table, coll. Staadt, 1969, MNHN-IM-2012-2350/4; Ile Krieu, coll. Blaise, MNHN-IM-2012-2362/2 juvenile shells; Lang-Son, coll. Letellier, 1949, MNHN-IM-2012-2366/1; Ile de la Table, coll. Demange, MNHN-IM-2012-2367/5; Dong-Trieu, coll. Blaise, MN HN-IM- 2012-2368/2; Halong Bay, leg. Messager, MNHN-IM-2012-2369/3; Halong Bay, leg. Messager, MNHN-IM-2012-2370/3; Halong Bay, leg. Messager, MNHN-IM-2012-2375/6; Tonkin, coll. Fischer, ex Crosse, MNHN-IM-2012-2380/2; Ilots de la Baie d’Along, leg. Messager, MNHN-IM-2012-2381/2; Tonkin, leg. Messager, MNHN-IM-2012-2388/1; Tonkin, coll. Lucas, Acc. no. 2351, NHMUK 20130622/2; Hanoi, Ile de la Table, coll. Biggs, H.E.J. ex Tomlin, 1931, Acc. no. 2258, NHMUK 20130623/8; Tonkin, coll. Salisbury ex Beddome, NHMUK 20130624/1; Tonkin, Ile de la Table, NHMUK 20130625/4; Tonkin, Ile de la Table, NHMUK 1901.12.12.211-212/2; Tonkin, Ile des Merveilles, NHMUK 1901.12.12.232-233/2; Tonquin, NHMUK 1889.9.23.1. (2 shells); Tonkin, Bah-Mun, coll. Dosch ex Rolle, SMF 172085/2 (" hirsuta "); Tonkin, Bah-Mun, coll. Ehrmann ex Fruhstorfer, SMF 150137/2 (" hirsuta "); Bah-Mun, leg. Fruhstorfer, 29.10.1900, RBINS/2 (" hirsuta "); Golfe de Tonkin, coll. Achat Boubée, MNHN-IM-2012-2307/1 (" hirsuta "); Tonkin, coll. Salisbury ex Beddome, NHMUK 20110254/1 (" hirsuta "); Tonkin, coll. Rolle, 4/11/01-25, NHMUK 20110264/3 (" hirsuta "); Tonkin, NHMUK 1916.3.16.10/1 (" hirsuta "); Tonkin, Bah-Mun, NHMUK 1901.12.23.32-34/3 (" hirsuta "); Tonkin, That-Khé, coll. Werner ex Rolle, NHMW 75000/E/7814/2; Tonkin, That-Khé, coll. Klemm, NHMW 79000/K/17484/3; Golf de Tonking, Ile de la Table, coll. Edlauer, NHMW 75000/E/14744/2; Tonkin, Ile Table, coll. Rušnov, NHMW 92583/2; Ile de la Table, Ban Valong (?), coll. Oberwimmer ex Caziot, NHMW 71640/O/9650/2; Tonkin, Ile de la Table, NHMW 92582/2; Tonkin, coll. Fruhstorfer, NHMW 40849/1; Tonkin, That-Ke, coll. Wagner ex Messager, NHMW 103351/2 (mixed sample with dautzenbergi ); Tonkin, NHMW 46025/1 (" hirsutus "); Cha-Ban, Baie d’Along, Tonkin, coll.Steenberg, ZMUC-GAS-1814/2.

New material examined.

20081119A Hải Phòng Province, Hải Phòng City, Cát Bà Isl., Cát Bà Nat. Park, beyond Mây Bầu, ca 160 m, 20°47.763'N, 107°00.758'E, leg. Ohara, K. 19.11.2008., PGB/2, OK/13; 20071122B same data, leg. Okubo, K., 22.11.2007., PGB/2; 20071122A Hải Phòng Province, Hải Phòng city, Cát Bà Island, Cát Bà Nat. Park, near pass in front of Mây Bầu, ca 100 m, 20°47.81769'N, 107°00.42256'E, leg. Ohara, K., 22.11.2007., OK/4, PGB/1; 20081118A Quảng Ninh Province, Hạ Long Bay, Đầu Gỗ Isl., near Đầu Gỗ Cave, ca 15 m, 20°54.696'N, 107°01.069'E, leg. Ohara, K., 18.11.2008., OK/14, PGB/2; GS25 Quảng Ninh Prov ince, Hạ Long Bay, Đầu Gỗ Cave, N. Đầu Gỗ Island, in leaf litter in limestone crackings, leg. Grego, J., 08.04.2012., PGB/1 broken specimen; 20071122C Hải Phòng City, Cát Bà Island, Cát Bà N.P., beyond Mây Bầu peak, 165 m, 20°47.70504'N, 107°00.85709'E, leg. Ohara, K., 22.11.2007., PGB/1; MAA7 Quảng Ninh Province, Hạ Long Bay Area, Áng Dù Island, 20°47.61'N, 107°08.05'E, coll. Maassen, W.J.M., 15.09.2003., PGB/2, WM/8; MAA8 Hải Phòng Province, Cát Bà Island, half way path lake Ao Ek and Park HQ, 20°47.45'N, 107°00.00'E, leg. Vermeulen, J., coll. Maassen, W.J.M., 27.09.2003. (2 shells); MAA11 Quảng Ninh Province, Hạ Long Bay Area, Tiên Ông Cave on Hang Trai? Island, collected near the entrance of the cave, 20°48.96'N, 107°07.33'E, coll. Maassen, W.J.M. 06.09.2003., (1 shell).; no code Quảng Ninh Province, Hạ Long Bay area, Cây Chanh Island, Cống Đỏ area, 20°52.56'N, 107°11.14'E, leg. Hemmen, Ch. & J., 2003, PGB/2 shells+1jb; MAA5 same data, coll. Maassen, W.J.M., 13.09.2003., PGB/2, WM/14; MAA2 Quảng Ninh Province, Hạ Long Bay Area, Cống Đỏ Isl., NE coast, 20°52.44'N, 107°12.10'E, leg. Vermeulen, J., 03.10.2003., coll. Maassen, W.J.M., WM/2; MAA3 Quảng Ninh Prov ince, Hạ Long Bay Area, unnamed island in Cống Đỏ area, 20°52.47'N, 107°11.72'E, coll. Maassen, W.J.M., 03.10.2003., PGB/1, WM/3); MAA4 Quảng Ninh Province, unnamed island in Đảo Mới Temper area, 20°55.69'N, 107°09.40'E, coll. Maassen, W.J.M., 13.09.2003., PGB/2, WM/18; MAA6 Quảng Ninh Province, Hạ Long Bay Area, Phao Trong Island, 20°49.80'N, 107°08.32'E, coll. Maassen, W.J.M., 11.09.2003., PGB/1, WM/5; 2012/26 Hải Phòng Province, Ðảo Cát Bà (island), Cát Bà Nat. Park, 500 m from the entrance towards Ao Ếch, 60 m, 20°47.945'N, 106°59.653'E, leg. Hunyadi, A., 22.05.2012., HA/1+2jb; 2012/28 Hải Phòng Province, Ðảo Cát Bà, Cát Bà Nat. Park, Ao Ếch 500 m towards Mây Bầu, 60 m, leg. Hunyadi, A., 22.05.2012., HA/25+1jb; 2012/32 Quảng Ninh Province, Đèo Bụt (pass) 1 km towards Cẩm Phả, right side of the road, 10 m, 20°58.680'N, 107°11.089'E, leg. Hunyadi, A., 23.05.2012., HA/11+1jb; 2012/34 Quảng Ninh Province, ÐảoTrà Bản (island), Cảng Bản Sen (harbour) 1.5 km towards Cảng Tân Lập (harbour), right side of the road, 30 m, 20°56.943'N, 107°29.772'E, leg. Hunyadi, A., 24.05.2012., HA/84+3jb; 2012/35 Quảng Ninh Province, ÐảoTrà Bản (island), Cảng Bản Sen (harbour) towards the Cảng Tân Lập (harbour) cross, 200 m, right side of the road, 35 m, 20°56.456'N, 107°29.870'E, leg. Hunyadi, A., 24.05.2012., HA/12; Vn11-172 Hải Phòng Province, Cát Bà Island, behind cemetery of Gia Luận village, 20°50.092'N, 106°58.560'E, leg. Hemmen, Ch. & J., 10.04.2011., HE/6 (anatomically examined); Vn11-173 Hải Phòng Province, Cát Bà Island, at km 4 road Gia Luận village to Cát Bà village, 20°49.991'N, 106°58.382'E, leg. Hemmen, Ch. & J., 10.04.2011., HE/11, PGB/1 (in ethanol); Vn11-174 Hải Phòng Province, Cát Bà Island, between Hiền Hào and Cát Bà village near Xuân Đán, 20°45.479'N, 106°58.556'E, leg. Hemmen, Ch. & J., 10.04.2011., HE/8; Vn11-175 Hải Phòng Province, Cát Bà Island, between Hiền Hào and entrance of Cát Bà N.P. (road over Hiền Hào), 20°47.681'N, 106°59.068'E, leg. Hemmen, Ch. & J., 11.04.2011., HE/4; Vn11-38A Hải Phòng Province, Cát Bà Island, Hoa Cương Cave (=Dong Da Hoang?), near Gia Luận, ca. 30 m, 20°50.268'N, 106°59.019'E, leg. Hemmen, Ch. & J., 10.04.2011., HE/5; Vn11-165 Quảng Ninh Province, ca. 8.3 km west of Cẩm Phả ca 200 m right of road 18 (no GPS-data), leg. Hemmen, Ch. & J., 03.04.2011., HE/1; VERM1 Cát Bà, Hải Phòng Province, Cát Bà Island, path from Nat. Park HQ to lake Ao Ek, 20°47.45'N, 107°00.45'E, Pri mary forest on limestone. Mainly handpicked. leg. Vermeulen, J.J. & Whitten, A.J., 25.09.1998, NHMUK 19991447/4; VERM3 Hạ Long Quảng Ninh Province, Hạ Long-Cẩm Phả area. Limestone hill S of Hạ Long, with marked regrowth and bamboo thickets, 20°57.00'N, 107°04.43'E, handpicked + soil sample, leg. Vermeulen, J.J. & Whitten, A.J., 28.09.1998 ex Vermeulen, nr. 6527, NHMUK 19991445/3; 20071122D Hải Phòng Province, Hải Phòng City, Cát Bà Island, Cát Bà Nat. Park, between Cát Bà N.P., ranger st. and Quan Y, GPS not recorded, leg. Ohara, K, Okubo, K. & Otani, J. U., 22.11.2007., coll PGB (in ethanol, anatomically examined).

Diagnosis.

Shell medium-sized to very large, thick shelled, almost smooth or with very fine periostracal ribs; apertural lip well-developed; apertural fold long, more or less equally long in its total length, connected to the callus. Parietal wall with missing or short anterior lamella (always distant from the upper plica) and well-developed posterior lamella; palatal plicae depressed Z-shaped.

Measurements

(in mm). D = 16.6-17.1, H = 8.3-8.5 (n=2, MAA5); D = 17.4-19.9, H = 7.9-9.2 (n=2, MAA4); D = 16.1-19.8, H = 7-9.4 (n=2, MAA6); D = 23.1-23.4, H = 10.8-11 (n=2, 20081119A); D = 24.8-25.6, H = 11.7-13 (n=4, Vn11- 174); D = 26-28.1, H = 12.8-13.1 (n=3, Vn11-175); D = 16.9-17.4, H = 8.2-8.4 (n=3, NHMUK 20110264, " hirsuta "); D = 16.5-17.3, H = 8.1-8.5 (n=3, NHMUK 1901.12.23.32-34, " hirsuta ") (see also Figure 44).

Differential diagnosis.

Gudeodiscus dautzenbergi and some populations of Gudeodiscus villedaryi resemble Halongella schlumbergeri in terms of general, but the inner lamellae are entirely different, namely, Gudeodiscus dautzenbergi and Gudeodiscus villedaryi have strong, well-developed anterior lamella with an anteriorly elongated lower “leg”, whereas most Halongella schlumbergeri shells lack the anterior lamella. It is possible to distinguish Halongella schlumbergeri from the other two species without breaking the shell, on the basis of the long apertural fold reaching the callus, which is short in Gudeodiscus dautzenbergi and Gudeodiscus villedaryi , and has an elevated “knob” part in some distance from the callus. See also under Halongella fruhstorferi .

Intraspecific diversity.

The species is very variable in terms of shell size and the formation of plicae and lamellae on the parietal wall.

Description of the genitalia.

Two specimens were examined anatomically each from one of two different samples. “Specimen1”: Hải Phòng Province, Cát Bà Island, behind cemetery of Gia Luận village, 20°50.092'N, 106°58.560'E, leg. Hemmen, Ch. & J., 10.04.2011. (with embryo in its uterus, Figures 26, 29H, 33B, F); “Specimen2”: Hải Phòng Province, Hải Phòng City, Cát Bà Island, Cát Bà Nat. Park, between Cát Bà N.P., ranger st. and Quan Y, GPS not recorded, leg. Ohara, K, Okubo, K. & Otani, J. U., 22.11.2007. (without embryo in its uterus, Figures 29 A–B, 30 G–I, 33A, C–E, G).

Penis relatively long, slimmer proximally and slightly thicker distally; inner wall with several (16-18) parallel running folds (Figures 29 A–B); between the folds flat, T-shaped calcareous granules were found (both specimens had granules between the folds, see Figures 30 G–I); epiphallus of similar length to the penis, proximally thicker than distally; its inner wall with six parallel folds; on the distal portion of the epiphallus the longitudinal folds have several perpendicular projections which overlap with those of the neighbouring fold (Figures 29H); penial caecum absent, the retractor muscle inserts on the penis-epiphallus transition. Vagina long, with a weak vaginal bulb; it is attached to the body wall with several filaments of connective tissue; inner wall of the vagina with 6-11 parallel, rather regular longitudinal folds; in “Specimen2” there are several, translucent calcareous granules on the folds; the granules have a widened base portion which attaches to the folds, and an apical part with some (1-10) pointed needles (Figure 33A, C–E, G); “Specimen1” had tiny rounded granules ( “sand”) in the vagina lumen, not attached to the vagina wall (Figure 33F); stalk of the gametolytic sac with conspicuously thickened gametolytic sac is longer than the much slimmer diverticulum.

Radula.

See Table 6 and Figures 36 D–F.

Distribution

(see Figures 40 and 44). The species has only been recorded in the Hạ Long Bay area (Hải Phòng and Quảng Ninh provinces).

Remarks.

Gude (1901b) figured specimens of all three “species”: schlumbergeri , jovia and villedaryi (later re-named pilsbryana ). His observations were based on one specimen from each “species”. He wrote the following: "A comparison of these three species has shown that that they are very closely allied, and that there is no difference of diagnostic value between the armature. They differ, however, in external aspect sufficiently to rank as separate forms. Plectopylis jovia is the largest of the three, while Plectopylis villedaryi is the smallest, Plectopylis schlumbergeri being intermediate in size." The additional differences mentioned by Gude, namely the strength of the callus, direction and small differences in the shape of the palatal and parietal lamellae and plicae are not sufficient to separate species. We had the possibility to observe and measure a number of shells collected in the Hạ Long Bay Area and provided with exact GPS data. The outer shell characters exhibit little variation other than in size. Therefore, we suggest synonymising the three species under one name.

The shell differences between Plectopylis schlumbergeri (and its synonyms) and Plectopylis hirsuta , namely the short or missing anterior lamella in schlumbergeri and the relatively “normal” anterior lamella of hirsuta are considered to be very minor. This trait shows clinal variation across shells assigned to hirsuta and schlumbergeri (and its synonyms). We therefore synonymize Plectopylis hirsuta with Halongella schlumbergeri .