Hystricella echinulata (R. T. Lowe, 1831)

Mattia, Willy De, Neiber, Marco T. & Groh, Klaus, 2018, Revision of the genus-group Hystricella R. T. Lowe, 1855 from Porto Santo (Madeira Archipelago), with descriptions of new recent and fossil taxa (Gastropoda, Helicoidea, Geomitridae), ZooKeys 732, pp. 1-125 : 18-22

Hystricella echinulata (R. T. Lowe, 1831) Figs 77-78, 79-82, 83-93, 94

List of synonyms.

1831 Helix echinulata R. T. Lowe: 57, pl. 6 fig. 19.

1846 Helix echinulata - L. Pfeiffer: 140, pl. 91 figs 1-4.

1847 Helix echinulata - L. Pfeiffer in L. Pfeiffer 1847-1848: 190.

1854 Helix echinulata - Reeve in Reeve 1851-1854: pl. 142 figs 9-10.

1854 Helix echinulata - Albers: 36, pl. 9 figs 1-4.

1855 Helix ( Hystricella ) echinulata - R. T. Lowe: 186.

1867 Helix (Octephila) bicarinata var. α echinulata - Paiva: 45.

1878 Helix (Hystricella) echinulata - Wollaston: 160-161.

1950 Discula (Hystricella) echinulata - Mandahl-Barth: 31, 55.

1983 Discula (Hystricella) echinulata - Waldén: 267.

2002 Geomitra echinulata - Bank et al.: 124.

2008 Hystricella echinulata - Seddon: 79, pl. 29 fig. D (and cf. E [under H. bicarinata ]), map 178.

2011 Hystricella echinulata - Seddon: e.T6727A12801253.

Type material.

NHM 1968.586, lectotype (herewith designated) of Helix echinulata R. T. Lowe, 1831 ex coll. R. T. Lowe. For the original figure of Helix echinulata R. T. Lowe, 1831 from R. T. Lowe (1831: pl. 6 fig. 19) and the lectotype of H. echinulata R. T. Lowe, 1831, W = 4.9 mm, Phot. B. Faria, D RAM, see Figs 77 and 78.

Further material examined.

All from Porto Santo, ANSP H 11829/1, Ribeiro do Pedregal, 33°06'10"N / 16°19'25"W, 35 m, leg. K. Groh & J. Hemmen, Jul. 11 1983; ANSP H 11828/16, CKG/5, Pico do Ninho do Guincho, 33°06'07"N / 16°18'51"W, 100 m, leg. K. Groh & J. Hemmen, Jul. 11 1983; CKG/1, Ribeiro do Golfeiras E Camacha, 33°05'47"N / 16°19'33"W, 170 m, leg. K. & C. Groh, Oct. 25 1980; ANSP H 11831/3, CKG/1, CMN/1, SW slope of Lombo Branco, under stones, 33°05'46"N / 16°18'46"W to 33°05'38"N / 16°18'13"W, 150-400 m, leg. K. Groh & J. Hemmen, Jul. 8 1983; ANSP H 11830/4, Terra Chã, top, 33°05'46"N / 16°18'14"W, 360 m, leg. J. Gerber, K. Groh & J. Hemmen, Aug. 14 1985; CFW 11162/5, Pico Branco, Terra Chã (350 m E of Pico Branco), 33°05'39"N / 16°17'58"W, 340 m, leg. F. Walther, Mar. 31 2017; CWDM/19, CMN/5, Terra Chã, near the "Casa Forestal", under stones in pine wood. 33°05"39"N/ 16°20'00"W, 340 m, leg. W. De Mattia & J. Macor, May 2014; CWDM/6, Terra Chã-Pico Branco ridge, under stones, 33°05'38"N / 16°18'01"W, 335 m, leg. W. De Mattia & J. Macor, May 2015; ANSP H 11833/3, summit of Pico Branco, 33°05'38"N / 16°18'14"W, 450 m, leg. K. Groh & J. Hemmen, Jul. 8 1983; ANSP H 11836/15 [sub H. leacockiana ], Pico Branco, 33°05'38"N / 16°18'14"W, above 350 m, leg. J. Gerber, K. Groh & J. Hemmen, Aug. 14 1985; CKG/16, Terra Chã, top, 33°05'36"N / 16°18'14"W, 360 m, leg. J. Gerber, K. Groh & J. Hemmen, Aug. 14 1985; CKG/2, Terra Chã, 33°05'31"N / 16°18'16"W to 33°05'38"N / 16°18'13"W, 320-400 m, leg. K. Groh & J. Hemmen, Jul. 8 1983; CWDM/14, path to Pico Branco, eastern steep part of path to Pico Branco, under stones, 33°05'29"N / 16°18'14"W, 320 m, leg. W. De Mattia & J. Macor, May 2014; CFW 11148/<10, SW slope of Pico Branco ca. 250 m SW of the top, 33°05'29"N / 16°18'13"W, 310 m, leg. F. Walther & E. M. Gryl, Mar. 31 2017; ANSP H 11826/7, approx. 1 km N Serra de Dentro, 33°05'24"N / 16°18'27"W, 165 m, leg. J. & C. Hemmen, Jan. 6 1981; ZMH 24292/1, Madeira Archipelago, without exact locality data, ex coll. Altonaer Museum, ex coll. O. Semper, ex coll. Dohrn; ZMH 24291/1, Porto Santo, without exact locality data, ex coll. Museum Klagenfurt.

Locus typicus.

Hab. in monte "Pico Branco" dicto Insulae Portus Sti.

Original description.

From Lowe 1831: H. testa parvula, conoidea, sub-pyramidata, depressiuscula, supra planulata, perforata, carinata, tota scaberrima, fusca, suprà fasciata: spira pyramidata elevata; sutura distincta, impressa; anfractibus convexis; ultimi carina acuta, distincta, supra marginata sc. sulco expressa vel exarata; omnibus granulis distinctissimis, conferitis, asperrimis scobinatis et quasi echinulatis; umbilicus parvo, sub-spirali, aperto; apertura rotundata; peristomate continuo, circinato, disjuncto, reflexo. Axis 2 lin. Diam. 2½. Anfr. 6.

Diagnostic features of the shell.

Shell as in the genus description. The main diagnostic feature is the presence of only one keel along the body whorl. The overall shape of the shell of H. echinulata is always conical but not scalariform as in H. bicarinata . The whorls are rounded and lack the typical “shoulder”. The sutures are deep, but less deeply marked than in H. bicarinata (see Figs 79-82).

Measurements.

D 5.2 ± 0.3 mm (range 4.6-5.8 mm); H 4.8 ± 0.5 mm (range 4.3-5.0 mm); FW 2.5 ± 0.2 mm; PA 42.6 ± 8.3; DU 0.5 ± 0.08 mm; NT 23 ± 9; NW 5.6 ± 0.1 (n = 40). Ratio D/H 1.1; ratio FW/H 0.5.

Body.

Body as in the genus description. The colour of the head and the neck is somewhat darker than in H. bicarinata .

Genital anatomy.

As in the genus description. Main diagnostic features are as follows. The free oviduct is usually very short and four times shorter than the vagina. The penial flagellum is usually as long as the epiphallus. It has a remarkably cylindrical shape and a blunt apex. Its internal walls are completely smooth, without any papillae. The genital atrium is always elongated. See Figs 83-93.

Ecology.

Hystricella echinulata is recorded from low (20 m a.s.l.) to relatively high altitudes (450 m a.s.l.). Except for the slightly higher altitudinal range, this species shares the same ecology as H. bicarinata ; it is commonly found under volcanic rocks scattered on grassland in open fields that are usually sloping. It has also been found in cracks and crevices or among scree on steep slopes.

Distribution.

Hystricella echinulata is endemic to the island of Porto Santo (Madeiran Archipelago, Portugal). The species is restricted to the northeastern, mountainous part of the island and present only in the Pico Branco-Terra Chã massif area. It is commonly found along Faja Pequena and the ridge and the south-exposed slope eastwards of Terra Chã (Fig. 94). No populations are known from the offshore islets.

Comparison and comments.

See under H. bicarinata and/or the section on putative hybrids of H. bicarinata and H. echinulata above.

Status and conservation.

According to Seddon (2011b) the species is Least Concern (LC), but in our opinion, the species should be considered as Endangered (EN B1a, b(i, ii, iv), 2a, b(i, ii, iv)) because its area of occupancy and extent of occurrence is less than 8 km2 and because it is mostly restricted to the highest elevations in the north-eastern part of Porto Santo and only occurs at scattered and isolated places with suitably humid microclimates. Mayor threats to the species include an observed decline of suitable habitats, extent of occurrence and area of occupancy over the past 30 years, i.e. as the result of longer drought periods which are possibly associated with effects of climate change, an increase of fire incidents, grazing by goats and to a lesser extent also hiking as tourism is increasing on Porto Santo. As most of the known localities are concentrated in the Pico Branco-Terra Chã area in the north-easternmost part of Porto Santo (Fig. 94), we consider that the species is not present at more than five locations.