Ruthenica, 2006, 16(1-2): ****. ©Ruthenica, 2006

A new species of the genus Merdigera Held, 1837 (Gastropoda: Pulmonata: Enidae) from Northwest Caucasus

Pavel V. KIJASHKO

Zoological Institute of Russian Academy of Sciences, Universitetskaya embankment, 1, Saint-Petersburg, 199034, RUSSIA

ABSTRACT. A new species Merdigera invisa Kijas- Mountains (Adygeja, Norhwest Caucasus). All of hko sp. nov. from the high-mountainous part of Nor- them were identified as a new species of Merdigera. thwest Caucasus is described. Taking into account the This species is described below. characters of this species, the diagnosis of the subfa- mily Merdigerinae Schileyko, 1984 is defined more exactly. Family Enidae Woodward, 1903 Subfamily Merdigerinae Schileyko, 1984 Genus Merdigera Held, 1837 Type species — Helix obscura Müller, 1774 There are discordant literature data on the dist- ribution of molluscs of the genus Merdigera Held, Merdigera invisa Kijashko, sp. nov. 1837 (type species — Helix obscura Müller, 1774) on Caucasus. A. Schileyko [1984] excludes Cauca- (Figs. 1 A, B, C) sus from the range of the sole representative of this genus, believing that «Multiple mentions about the Material. Northwest Caucasus, Adygeja, Lagonaki presence of the species “Ena” obscura on Caucasus Mountains, southern foot of Lagonaki Ridge, right river- bank of Tsitse (right tributary of the river Psheha), (~ are due to the fact that the shell of this species is 1200 m above sea level), lime rocks. June 29, 2001; extremely similar to caucasian Akramovskiella um- coll. P.V. Kijashko (holotype and paratypes). Holotype brosa (Mousson, 1873)...» [Schileyko, 1984]. A. and 17 paratypes are stored in the Zoological Institute Kuznetsov [1999] published data that expanded the of Russian Academy of Sciences (St.-Petersburg, № 527- range of Merdigera obscura (Müller, 1774) from 2006). Europe eastward up to Dzungaria. Among other Diagnosis. The shell practically does not differ territories included into the range of this species, he from that of Merdigera obscura and Akramovskiella mentioned northwest Caucasus. However, molluscs umbrosa. Epiphallus approximately twice longer from Caucasian were not included in the list of than penis, without sharp flexures, flagellum very material studied by him. In the “Catalogue of mol- short. Border between penis and epiphallus not clear. luscs of Russia and adjacent countries” by Yu. Kan- Penis and penial appendix devoid inflations, verges tor and A. Sysoev [2005], the range of M. obscura and papillas, distal part of penis with thick walls, is given according to Kuznetsov. It includes Wes- proximal rather thin-walled, inner surface smooth, tern, Central and partially Southern Europe; Balkan with small blurred annular pillaster on border with Peninsula; northwest Africa; territories of Byelorus- epiphallus. Penial appendix weakly subdivided into sia (Vitebsk Region); Russia (the Tver, Smolensk, sections. A1 by its size and shape similar to proximal Yaroslavl regions, suburbs of St.-Petersburg and part of penis, inside with high annular pilaster on Moscow, northwest Caucasus); Ukraine (mountain border between A1 and A2. A2 — thin-walled, ap- Crimea); Uzbekistan (western Tien Shan) and Ka- proximately twice as long as A1. Diverticle of sper- zakhstan (Dzungaria). Taking into account the pre- mathecal stalk reaching albuminous gland. Penial sence of Merdigera in Crimea, Central Asia and retractor with two branches standing apart immedi- Kazakhstan, molluscs of this genus undoubtedly ately near to male ducts, one branch attached to should live on Caucasus as well. However, I could proximal part of penis, another to middle of A1. not find information about specimens of Merdigera [Диагноз. Раковина практически не отличается от from Caucasus reliably identified by anatomic cha- Merdigera obscura и Akramovskiella umbrosa. Флагел- racters. люм очень короткий, иногда практически отсутствует. Эпифаллус примерно в два раза длиннее пениса, без In summer 2001, eighteen specimens of terrest- резких изгибов. Граница между пенисом и эпифаллу- rial molluscs similar to Merdigera obscura have сом не выражена. Пенис и пениальный аппендикс ли- been collected by me in the expedition to Lagonaki шены вздутий и папилл, дистальная часть пениса с 2P.V. Kijashko

FIG. 1. Merdigera invisa sp. nov. A — shell (holotype); B — reproductive tract (paratype); C — interior of penis and proximal part of appendix (paratype); a1, a2, a3, a4, a5 — divisions of penial appendix; ag — albumen gland; dst — diverticle of spermatheca; e — epiphallus; ec — epiphallic caecum; f — flagellum; p — penis; pil — pilaster; pr — penial retractor; rs — reservoir of spermatheca; v — vagina; vd — vas deferens. Scale bar 1 mm. РИС. 1. Merdigera invisa sp. nov. А — раковина (голотип); В — половая система (паратип); С — внутреннее строение пениса и проксимальной части пениального аппендикса (паратип); a1, a2, a3, a4, a5 — отделы пе- ниального аппендикса; ag — белковая железа; dst — дивертикул семяприемника; e — эпифаллус; ec — цекум эпифаллуса; f — флагеллум; p — пенис; pil — пилястр; pr — пениальный ретрактор; rs — резервуар семяприемника; v — вагина; vd — семяпровод. Масштаб 1 мм.

толстыми стенками, проксимальная относительно тон- и форме сходен с проксимальным отделом пениса, костенная. Внутренняя поверхность гладкая, на гра- внутри, на границе между А1 и А2 имеется мощный нице с эпифаллусом имеется небольшой расплывшийся кольцевой пилястр. А2 — тонкостенный, приблизи- кольцевой пилястр. Пениальный аппендикс внешне тельно вдвое длиннее А1. Дивертикул семяприемника слабо дифференцирован на отделы. А1 по размерам достигает белковой железы. Пениальный ретрактор с New species of Merdigera Held, 1837 3

двумя ветвями, обособляющимися непосредственно border between A1 and A2. Possibly these differences вблизи мужских половых протоков, одна ветвь кре- are a result of a single-stage reduction (without in- пится к проксимальной части пениса, а другая к се- termediate forms) of the penial structures. редине А1.] The description of new species Merdigera makes Description. Shell ovate-conic, rather thin, dull. necessary to update the diagnosis of the subfamily Embryonic whorls (about 2) smooth, postapical Merdigerinae Schileyko, 1984. whorls (about 5-6) brownish-corneous, with weak irregular radial wrinklets. Upper whorls convex, Subfamily Merdigerinae Schileyko, 1984 with deep suture, lower whorls rather flattened. Last whorl (about half height of shell) very weakly ele- vated before aperture. Aperture ovate, slightly obli- Shell weakly sculptured. Aperture toothless. Em- que. Margins thin, moderately reflexed, with blurred bryonic whorls smooth. Epiphallus with short roun- ded flagellum. Epiphallic caecum well developed. lip. Columellar margin reflexed more strongly in Penis short, containing closed short thin-walled comparison with others and slightly covers slit-like umbilicus. verge, penis with very thin, transparent walls. If verge absent, penis with significantly thicker walls Dimensions: height 7.5-8.0 mm; diameter 3.3- and contains blurred annular pilaster on border with 3.5 mm; height of aperture 2.5-2.8 mm; width of epiphallus. Prismoconic tubercles or proximal pro- aperture 2/1-2.3 mm. Dimensions of holotype: 7.8; cess of penis absent. Penial appendix weakly diffe- 3.3; 2.7; 2.3, respectively. rentiated into sections. A short, A comparatively Reproductive anatomy. Albuminous gland with 1 2 large, with subglobular papilla similar to penial weak apical groove, upper vagina three times longer verge or there is a high annular pilaster on border lower. Vas deferens entering epiphallus laterally, between A and A . A rather long. Diverticle of leaving very short rounded flagellum. Sometimes 1 2 3 spermathecal stalk well developed. (in 1 specimen of 5 dissected) flagellum reduced Distribution. Europe; Western Caucasus; Cen- and vas deferens entering epiphallus almost apically. tral Asia; Kazakhstan; Northwest Africa. 2 species: Epiphallus approximately twice longer than penis, Merdigera obscura (Müller, 1774), Merdigera in- without sharp flexures, with small rounded caecum. visa sp. nov. Border between penis and epiphallus not clear. Penis and penial appendix lacking inflations, verges and papillae, distal part of penis with thick walls, prox- References imal rather thin-walled, inner surface smooth. Penial Kantor Yu.I., Sysoev A.V. 2005. Catalogue of mol- appendix weakly differentiated into sections. A1 si- milar to proximal part of the penis in size and shape, lusks of Russia and adjacent countries. Moscow: KMK Scientific Press Ltd. 627 p. inside with high annular pilaster on border between Kuznetsov A.G. 1999. New data on land snails of A1 and A2. Ecology. Species inhabits calcareous rocks in the family Enidae (Gastropoda, Pulmonata) from Central Asia. Ruthenica, 9(2): 101-112. high-mountain forests, and on border of forest and alpine zones (1200-1800 m above sea level). Schileyko A.A. 1984. Terrestrial mollusks of the suborder Pupillina of the USSR fauna (Gastro- Etymology. The name of new species comes poda, Pulmonata, Geophila). In: Fauna USSR, from Latin invisus (invisible) as the shells of these N.S., N.130 Mollusca. Vol. III, pt. 3. 399 p. molluscs is covered with a crust of calcareous dust [in Russian]. and bits of lichens glued by mucus, making it diffi- cult to find. z Remarks. The shell of the new species practi- cally does not differ from that of Merdigera obscura (Müller, 1774) and Akramovskiella umbrosa (Mo- Новый вид рода Merdigera Held, 1837 (Gas- usson, 1873). Minor differences which I could find tropoda: Pulmonata: Enidae) с Северо-Запад- virtually disappear owing to individual variability ного Кавказа of specimens, clearly seen into comparison of nume- rous shells. Particular characters of the genital ap- П. В. КИЯШКО paratus (absence of inflations of penis and appendix, Зоологический Институт РАН, Университетская на- the shape of appendix and penial retractor) indicate бережная 1, Санкт-Петербург 199034, РОССИЯ the belonging of described species to Merdigera. РЕЗЮМЕ. Приводится описание нового вида Mer- Anatomically M. invisa differs from M. obscura by digera invisa Kijashko sp. nov. из высокогорной the absence of verge or papilla inside penis and части Северо-Западного Кавказа. С учетом призна- penial appendix respectively. Instead there are an- ков нового вида уточняется диагноз подсемейства nular pilasters: a small blurred pilaster on border Merdigerinae Schileyko, 1984. between penis and epiphallus and a high pilaster on