Auriculella gagneorum, Yeung & Slapcinsky & Strong & Kim & Hayes, 2020

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 gagneorum sp. nov. Figures 1F , 3K, L , 4F , 5F , 6A-C

Material examined.

Holotype: USA • 1, H = 4.7 mm, W = 3.4 mm, AH = 2.3 mm, AW = 1.8 mm, WH = 5.3 whorls; Honolulu County, Oahu, Waianae Mountains, Palawai Gulch; 710 m; 9 Feb. 2018; K. A. Hayes, N. W. Yeung, J. Slapcinsky; hand collected on Pisonia umbellifera ; GenBank: MT519824-MT519826, MT519866-MT519868, MT519889-MT519592; BPBM 285843.

Paratypes: USA - Honolulu County, Oahu, Waianae Mountains • 1; Puu Hapapa; 23 Jan 2013; D.T.A. Gary, K. Leung, D. R. Sischo, V. J. Costello; BPBM 285794 • 8; Puu Hapapa; 23 Jan 2013; D.T.A. Gary, K. Leung, D. R. Sischo, V. J. Costello; BPBM 285795 • 1; Palawai; 24 Dec 2014; D. R. Sischo and SEPP crew; BPBM 285799 • 3; Puu Hapapa; 24 Jan 2013; D.T.A. Gary, K. Leung, D. R. Sischo, V. J. Costello; BPBM 285796 • 2; Ekahanui; 17 Feb 2013; D.T.A. Gary, K. Leung, D. T. B. Ressler, V. J. Costello; BPBM 285797 • 1; Palawai; 24 Dec 2014; D. R. Sischo and SEPP crew; BPBM 285798 • 2; Palawai; 24 Dec 2014; D. R. Sischo and SEPP crew; BPBM 285800.

Other material: USA - Honolulu County, Oahu, Waianae Mountains • 37; Palikea Ridge; 12 October 1912; R. von Holt, Cooke; BPBM 24989 • 44; Palikea Ridge; 12 October 1912; von Holt, Cooke; BPBM 33011 • 27; Palikea Ridge; 12 October 1912; von Holt, Cooke; BPBM 33018 • 10; Palikea Ridge; 12 October 1912; von Holt, Cooke; BPBM 33006 • 3; Makua; 16 November 1913; Spalding; BPBM 34847 • 3; Palikea Ridge; 27 December 1914; Alice T. Cooke, C.M. Cooke; BPBM 38031 • 79; Palikea Ridge; 24 August 1922; R. von Holt, C.M. Cooke Jr., M.C. Neal; BPBM 59612 • 11; Napepeiauolelo; 25 March 1934; Meinecke, William H.; BPBM 127221 • 1; Palawai Gulch; 30 August 1935; D’Alte A. Welch, Glen W. Russ; BPBM 174037 • 15; Palawai Gulch; 30 August 1935; Glen W. Russ, D’Alte A. Welch; BPBM 174233 • 2; Palawai Gulch; 30 August 1935; D’Alte A. Welch, Glen W. Russ; BPBM 174141 • 3; Palawai Gulch; 30 August 1935; D’Alte A. Welch, Glen W. Russ; BPBM 174081 • 1; Manuwaikaalae Gulch; 28 March 1936; J. Winne, D’Alte A. Welch; BPBM 176456 • 2; Pohakea Gulch; 30 March 1936; J. Winne, D’Alte A. Welch; BPBM 176596 • 3; Pualii Gulch; 30 March 1936; J. Winne, D’Alte A. Welch; BPBM 176651 • 21; Pualii Gulch; 30 March 1936; J. Winne, D’Alte A. Welch; BPBM 176766 • 1; Kaaikukai Gulch; 03 April 1936; B. Bowen, D’Alte A. Welch; BPBM 176916 • 11; Kaaikukai; 03 April 1936; B. Bowen, D’Alte A. Welch; BPBM 176973 • 15; Palawai Gulch; 19 April 1936; J. Winne, D’Alte A. Welch; BPBM 177217 • 9; Palawai Gulch; 19 April 1936; J. Winne, D’Alte A. Welch; BPBM 177278 • 1; Kaaikukai Gulch; 05 May 1936; R. Yamaguchi, D’Alte A. Welch; BPBM 177468 • 1; Mount Kaala; 27 March 1937; F. Raymond Fosberg; BPBM 162712 • 11; Napepeiauolelo; 03 April 1938; William H. Meinecke, E. Meadows, Donald Anderson; BPBM 173979 • 9; Napepeiauolelo; 03 April 1938; William H. Meinecke, E. Meadows, Donald Anderson; BPBM 173980 • 2; Pualii Gulch; 03 April 1938; William H. Meinecke, E. Meadows,, Donald Anderson; BPBM 184885 • 5; Ekahanui Gulch; 16 September 1941; Rokuro Yamaguchi, Yoshio Kondo; BPBM 211563 • 2; Ekahanui Gulch; 16 September 1941; Rokuro Yamaguchi, Yoshio Kondo; BPBM 211678 • 6; Ekahanui Gulch; 16 September 1941; Rokuro Yamaguchi, Yoshio Kondo; BPBM 211723 • 5; Napepeiauolelo-Pualii Ridge; 15 October 1960; Yoshio Kondo, T.M. {T. Maa?}, George F. Arnemann, P.C. {Peter Char?}; BPBM 216123 • 2; Palawai Gulch; BPBM 183862 • 135; Palikea Ridge; R. von Holt, Cooke; BPBM 21823 • 17; Palikea Ridge; R. von Holt, Cooke; BPBM 21824 • 74; Palikea Ridge; Spalding; BPBM 22739 • 6; Palikea Ridge; Spalding; BPBM 19891 • 1; Palikea Ridge; Cooke; BPBM 16884.

Type locality.

Palawai Gulch, Waianae Mountains, Honolulu County, Oahu

Diagnosis.

Shell. Shell sinistral with inflated whorls, H = 4.8 ± 0.3 mm, W = 3.2 ± 0.2 mm, WH = 5.4 ± 0.4, AH = 2.3 ± 0.1 mm, AW = 1.7 ± 0.1 mm (Table 2 ). Columella in juveniles with a strong lamella that is reduced and covered by a thickening of the inner edge of the lip in adults. Adults do not show a short projection or angular edge where the columellar lamella was located. Parietal lamella is often undulate, usually with three peaks, extending 0.2 to 0.5 whorls into the aperture. Shell color is white, pale tan or dark brown, with or without irregularly placed axial bands of brown, or with a single peripheral band of pale tan or dark brown. Specimens occasionally pale tan with two poorly defined dark bands on either side of a pale tan peripheral band.

Reproductive system. Phallus retractor muscle long, attached apically to a short but well-defined epiphallus (Fig. 4F ). Appendix slightly longer than the phallus. Appendix ⅔ the diameter of the phallus at its attachment, tapering gently to ⅓ its length, then remaining narrow to its terminus. Apical ¾ of the phallus is broad, tapering slightly both apically and basally, basal ¼ narrows slightly above junction with the short atrium. Vagina is short.

Radula . Radula with an irregular rachidian flanked on either side by rastriform marginal teeth, as diagnostic of the family (Fig. 5F ). 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. Number of teeth per row range from 135 to 153 (N = 3; Table 2 ).

Distribution and ecology.

Auriculella gagneorum sp. nov. is endemic to Oahu’s Waianae Mountain Range and was recorded as a potentially new species primarily from the southern Waianae Mountain Range, with several populations in the northern part of the range (Fig. 1F ). The species is arboreal and has been found on Antidesma platyphyllum , Broussaisia arguta , Lantana sp., Melicope anisate , Myrsine lessertiana , and occasionally on unspecified ferns and dead leaves. The last known record of this species prior to recent surveys was by Yoshio Kondo, T. Maa, George F. Arnemann, and Peter Char in 1960. From 2013 to 2018 we recorded extant populations of this species from three locations in the southern Waianae Mountains.

Remarks.

The shell is sinistral unlike A. minuta and the columella does not bear an axially oriented ridge like the one found in A. perversa . The palatal lamella is often undulate unlike all other members of the A. perpusilla group. The epiphallus is short but well defined similar to A. minuta but unlike the long epiphallus of A. perpusilla or the poorly defined epiphallus of A. perversa . The appendix tapers gently unlike the appendices of A. auricula , A. minuta , A. perpusilla , A. perversa , and A. tenella which all narrow abruptly.

Etymology.

Named in honor of Betsy and Wayne Gagne for their indefatigable efforts advocating for the conservation of Hawaii’s unique and highly endangered biota.

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.

Figure 6. Photographs of live animals of Auriculella gagneorum sp. nov. A eggs B 1 - day old juveniles C adult. Scale bars: 1 mm.