Auriculella perpusilla E. Smith, 1873

Yeung, Norine W., Slapcinsky, John, Strong, Ellen E., Kim, Jaynee R. & Hayes, Kenneth A., 2020, Overlooked but not forgotten: the first new extant species of Hawaiian land snail described in 60 years, Auriculella gagneorum sp. nov. (Achatinellidae, Auriculellinae), ZooKeys 950, pp. 1-31 : 1

Auriculella perpusilla E. Smith, 1873 Figures 1C , 3E, F , 4C , 5C

Auriculella perpusilla E. Smith in Gulick & Smith, 1873: 87, pl. 10, fig. 26; Pilsbry and Cooke 1915: 91-92, pl. 25, figs 1, 2; Cowie et al. 1995: 77; Johnson 1996: 193; Severns 2011: 210, pl. 82, fig. 3.

Type material.

Holotype: USA • 1; shell crushed; H = 4 mm, W = 2 ⅔ mm (according to original description); Honolulu County, Oahu, Koolau Mountains; 1918; John T. Gulick leg.; MCZ 39912.

Type locality.

“Kohalu” (sic, Kahaluu) on Oahu.

Diagnosis.

Shell. Shell sinistral with inflated whorls, H = 4.4 ± 0.26 mm, W = 3.0 ± 0.15 mm, WH = 5.0 ± 0.14, AH = 2.1 ± 0.14 mm, AW = 1.5 ± 0.11 mm (N = 50; Table 2f ). Columella in juveniles with a strong lamella that is reduced and covered by a thickening of the inner edge of the lip in adults. Some adults show a short projection or angulation where the columellar lamella was located. Parietal lamella is smooth and not undulate, extending 0.3 whorls into the aperture, and sometimes bears a weak angulation at mid-point. Shell color is pale tan or dark brown, with or without a single peripheral color band of pale tan or dark brown (Fig. 3F ).

Reproductive system. Phallus retractor muscle relatively short, attached apically to a long epiphallus, which is nearly ⅓ the length of the phallus (Fig. 4C ). Appendix is nearly equal in length to the phallus. Appendix slightly over half the diameter of the phallus at its attachment, narrowing abruptly at ⅓ its length and remaining narrow to its terminus. Apical ⅔ of the phallus is broad, basal ⅓ narrows abruptly and remains narrow to the junction with the short atrium. Vagina is long and nearly half the length of the phallus.

Radula . Radula with an irregular rachidian flanked on either side by rastriform marginal teeth, as diagnostic of the family (Fig. 5C ). Each tooth has a long narrow base that expands slowly for ¾ of the length of the tooth before reaching the forward curving cusps, which comprise the remaining ¼ of the tooth. There are three long cusps at mesocone, endocone, and ectocone positions with two or more alternating larger and smaller cusps intercalated between them. There are roughly 127 teeth per row (N = 5; Table 2 ).

Distribution and ecology.

Auriculella perpusilla is endemic to Oahu’s Koolau Mountain Range (Fig. 1C ), recorded from across the range at elevations of 61 m to 1066 m. The species is arboreal and found on vegetation, including: Antidesma pulvinatum , Cordyline fruticosa , Freycinetia arborea , Kadua affinis , Lobelia sp., Metrosideros polymorpha , Myrsine sp., Psidium guajava , Psychotria kaduana , Syzygium sandwicense , Touchardia latifolia , and on unspecified ferns, tree trunks, and dead leaves. Recent observations are restricted to Tantalus (southern Koolau Mountains; Fig. 1C ).

Remarks.

No holotype was designated in the original description which included a single figure and provided a single set of measurements: height 4 mm width 2 ⅔ mm. The shell donated by Gulick is MCZ 39912 and is labeled holotype. Pilsbry and Cooke (1915: 91) indicated that only a single shell existed; "The single specimen collected by Mr. Gulick and described by Mr. Smith, is unfortunately broken." Consequently, MCZ 39912 is the holotype by monotypy.

Unlike A. minuta , A. perpusilla is sinistral and the columella does not bear an axially oriented ridge like the one found in A. perversa . The palatal lamella is smooth and not undulate like A. gagneorum sp. nov. The epiphallus is long unlike the poorly defined epiphallus of A. perversa or the short but well-defined epiphallus of A. minuta and A. gagneorum sp. nov. The appendix narrows abruptly at approximately ⅓ its length unlike A. gagneorum sp. nov.

Figures

Figure 1. Distributional map of Auriculella spp. A Auriculella auricula B Auriculella minuta C Auriculella perpusilla D Auriculella perversa E Auriculella tenella and F Auriculella gagneorum sp. nov. Dark grey circle = historical; light grey triangle = since 2010.

Figure 3. Comparative shell morphology of A Auriculella auricula neotype BPBM 18709 B Auriculella auricula shell variation (left to right) BPBM 12651, BPBM 12666 C Auriculella minuta lectotype BPBM 42377 D Auriculella minuta shell variation (left to right) BPBM 12804, paralectotype MCZ 73037 E Auriculella perpusilla holotype MCZ 39912 F Auriculella perpusilla (left to right) BPBM 285806, BPBM 134341 (2 spm), BPBM 134280 white one, BPBM 122643, BPBM 13443 G Auriculella perversa lectotype BPBM 42384, 3 shells H Auriculella perversa shell variation (left to right) paralectotype ANSP 91817 I Auriculella tenella lectotype BPBM 18943 J Auriculella tenella shell variation paralectotype BPBM 109679 K Auriculella gagneorum sp. nov. holotype (BPBM 285843) and L Auriculella gagneorum sp. nov. paratypes, left to right (BPBM 285797, 285794, 285795, 285798). Scale bar: 5 mm.

Figure 4. Comparative reproductive anatomy of A Auriculella auricula BPBM 119141 B Auriculella minuta BPBM 99146 C Auriculella perpusilla BPBM 93626 D Auriculella perversa BPBM 97904 E Auriculella tenella BPBM 211034 F Auriculella gagneorum sp. nov. paratype BPBM 285800. Abbreviatons for reproductive structures are: AG = albumen gland; AP = penial appendix; BC = bursa copulatrix; EP = epiphallus; GP = gonopore; P = penis; OV = free oviduct; PG = prostate gland; PR = penial retractor muscle; UT = uterus; VD = vas deferens. Scale bar: 1 mm.

Figure 5. Comparative radular morphology of A A. auricula B A. minuta C A. perpusilla D A. perversa E A. tenella F A. gagneorum sp. nov. Scale bar: 10 μm.