Aegistohadra baii Wu 2023
Creators: name: Wu, Min
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Stylommatophora
Camaenidae
Aegistohadra
Aegistohadra baii

description: Aegistohadra baii sp. nov.
Figs 1; 2 C–D; 3; 4 D–E; 7; 8; 9 C–D
Zoobank regstration: urn:lsid:zoobank.org:act: 01EADDBB-9B8E-4E54-8BF8-8C360B1434CC
Material examined. Holotype (dissected): HBUMM08465 -spec.1, a fully mature animal with a sinistral shell; near 22º46.2’N 104º28.2’E, Maguanxian [Ḽ关县], Wenshan [Ý山], Yunnan Province, China; 04.10.2019, coll. Bai Hao-Chen. Paratypes: HBUMM08465 -spec.1, a fully mature sinistral shell, same data as holotype; HBUMM08463, a fully mature animal (dissected) with a dextral shell, same data as holotype. Measurement of holotype: shell height 21.7 mm, shell major diameter 30.1 mm, aperture height 11.0 mm, aperture breadth 14.3 mm, umbilicus diameter 3.6 mm, protoconch whorls 11 / 2, whorls 53 / 8.
Diagnosis. Shell conical, dextral or sinistral. Body whorl peripherally rounded. A large proximal accessory sac on proximal dart sac. Flagellum proximally swollen then abruptly thinned down.
Shell (Figs 2C–D; 3). Shell dextral or sinistral, conical, thin but solid, with 53 / 8 – 55 / 8 convex whorls. Suture deeply impressed. Protoconch 11 / 2 whorls, with sculpture obscured by weathering or abrasion (Figs 2D; 3B). Growth lines fine or thick. Spiral grooves unevenly distributed. Body whorl peripherally rounded.Aperture oblique, broadly ovate, suddenly descending in front. Peristome slightly expanded and reflexed except upper part. Columella oblique. Umbilicus small, approximately 1 / 9 of shell major diameter, slightly covered by reflexed columella. Shell is pale yellow with chestnut bands: one broad, beneath periphery; two broad bands above periphery of which the lower one slightly overlaps periphery; and the most upper one much narrower and close to suture. The first 21 / 2 whorls faintly colored or banded.
General anatomy (Figs 4 D–E; 7G). Neither eversible head wart nor gland pit leading to internal body present. For the dextral individual, at left side a broad but shortly projecting mantle lobe present (Fig. 4E, arrowed); for the sinistral snail such lobe is present on the opposite side on mantle edge. Suprapneumostomal lobes normally developed (Fig. 4D, arrowed). Body uniformly yellowish brown, without mosaic pigmentation. Sole creamy white. Jaw arcuate, with approximate 6 projecting ribs (Fig. 7G).
Genital anatomy (Figs 7 A–F; 8; 9 C–D). Penial sheath absent, except for some proximal connective tissue present near atrium. Penis tube-shaped, distally with a penial caecum of the same thickness and terminally roundly blunted. Proximal approximately 1 / 2 penis internally with two very thick smooth longitudinal pilasters, each branching off and broken into several series of granules, which form a more or less transversal ridge, or a papilla, which partially separates the penis and the epiphallus and the distal part of which extends into the penial caecum. Penis-epiphallus chamber absent. In penial caecum pilasters come from those of both penis and epiphallus. Epiphallus thinner than penis, internally with approximately 5 pilasters of the same thickness. Flagellum about as long as epiphallus, proximally swollen but suddenly thinned down; internally, one of inner folds forming a closed tube rather than an opened C-shaped pilaster towards terminal flagellum and opening at vas deference entrance. Penial retractor muscle attached at median portion of epiphallus. Vas deferens of same thickness, opening at internal epiphallus by a valve-like entrance. Dart sac developed, with an accessory sac below. Love dart single, fully calcified, symmetric along the longitudinal axis, fairly straight, about 8.0 mm long, with cross section apically two-bladed and then ovate (Fig. 7F). Accessory sac large in size, pear-shaped, with spongy internal wall, entering into dart sac chamber rather than into dart chamber. Mucous glands as long as dart sac, tied tightly to the trunk of vagina, with two lobules that are complicatedly branched. Two stalks of mucous glands merged into one, then entering chamber of accessory sac through a prominent papilla with several openings (Fig. 9C).A developed proximal accessory sac, in size about 1 / 2 of dart sac, present proximally on dart sac apparatus (for sinistral animal on the left side, for dextral animal on the right). Proximal accessory sac with a very thick muscular outer wall, opening to dart sac chamber near entrances of accessory sac and vagina (Fig. 9D). Vagina shorter than dart sac. Bursa copulatrix duct equally thin, slightly thinner than vagina. Bursa copulatrix oval.
Ecology. The animals live in karst hill area, inhabiting limestone rocks thick with lianas.
Distribution (Fig. 1). Aegistohadra baii sp. nov. is currently known from the type locality.
Remarks. This new species shares many conchological and genital characters with Aegistohadra delavayana [Heude, 1885; Wu, 2004], including sculpture on shell surface, shell coloration, presence of penial caecum, dart sac apparatus and flagellum. However, the new species can be immediately recognized by the smaller and more conical shell. In terms of genital the new species is characterized by having one large proximal accessory sac rather than two smaller proximal accessory sacs in A. delavayana. In addition, the shell shape and spiral bands of the new species (Figs 2 C–D; 3) fairly resemble those of Aegistohadra seraphinica (Heude, 1889) (Fig. 2 A–B) [fig. 33 in Wu, 2004], except that the former species has a relatively higher shell and a separate broad band around umbilicus.
Cryptozona yunlongensis Chen Y., Chen D. et Zhang, 1997, a dextral species known from Yunlong County of Yunnan Province [Chen et al., 1997], is undoubtedly a valid Aegistohadra species based on its shell morphology and anatomy of genital organs [partial opinion from Ding Yu-Tong, pers. comm.]. A. yunlongensis can be promptly distinguished from the sympatric A. delavayana by the different chirality, possessing carinate periphery and a tubular penial caecum. Conchologically, the new species differs from A. yunlongensis in the smaller shell size and the rounded periphery.
Most recently, the known distribution range of Aegistohadra was extended to Sichuan Province based on the finding of Aegistohadra delavayana (HBUMM 08485 spec.1–2) in Panzhihua, Sichuan Province by Mr Shen Yu-Han [沈榆涵] (Fig. 1).
Etymology. This new species is named after Mr Bai Hao-Chen, who collected the specimens and prepared the field data for this work.
description: Published as part of Wu, Min, 2023, A new Aegistohadra (Gastropoda: Camaenidae) from southwest China, pp. 59-71 in Ruthenica, Russian Malacological Journal (Cambridge, England: 2003) (Cambridge, England: 2003) 33 (2) on pages 60-66, DOI: 10.35885/ruthenica.2023.33(2).2, http://zenodo.org/record/11041496