Lerniana, Delicado & Hauffe, 2022

Delicado, Diana & Hauffe, Torsten, 2022, Shell features and anatomy of the springsnail genus Radomaniola (Caenogastropoda: Hydrobiidae) show a different pace and mode of evolution over five million years, Zoological Journal of the Linnean Society 196, pp. 393-441 : 433

LERNIANA GEN. NOV.

Z o o b a n k r e g i s t r a t i o n: z o o b a n k. org:act: AAB227D3-CBD8-4E8A-A001-4AA29A9B4256

Type species: Hydrobia tritonum Bourguignat, 1852 (also known as Semisalsa tritonum ; Schütt, 1980).

Etymology: The genus name refers to the Greek name Λέρνη, Lerna, a spring region that was once a lake and today is home to a population of the type species; gender feminine.

Diagnosis: Shell ovate-conic; 4.0–4.5 whorls; aperture oval with a straight narrow outer lip; umbilicus narrow. Operculum corneous, yellowish, thin, pliable, oval, without peg, and paucispiral with submarginal nucleus. One pair of basal cusps on radular central tooth. Ctenidium well developed, with 10–13 gill filaments. Osphradium positioned opposite approximate middle of ctenidium. Stomach without gastric caecum. Bursa copulatrix medium sized, pyriform, pedunculated and lying against the anterior section of the albumen gland; unpigmented renal oviduct; two seminal receptacles; SR2 smaller than SR1 and arising at the renal oviduct loop. Prostate gland bean shaped, about twice as long as wide. Penis strap-like, simple or with one small, medial outgrowth on its left side. Nervous system slightly pigmented, moderately concentrated.

Remarks: Lerniana is distinguished here from Radomaniola according to its smaller shell with a shorter spire, smaller stomach, pyriform bursa copulatrix with a shorter duct (of globular shape and with a longer duct in Radomaniola ), smaller SR2, strap-like penis [although sometimes also gradually tapering, see Falniowski etal. (2012: 29, fig.7G1, G5) and Georgiev (2013: 294, fig. 2.4)] with a small outgrowth on the left side (larger and gradually tapering with a more prominent outgrowth in Radomaniola ) and a generally more concentrated dorsal nerve ring ( RPG ratio <0.5 in Lerniana ) (Supporting Information, Figs S3 , S 7 , S 9 ). Moreover, all phylogenetic analyses congruently depicted the three species assigned to this new genus (i.e. R. tritonum , R. feheri and R. seminula ) as a well-supported clade outside Radomaniola ( Fig. 2 ). Falsibelgrandiella Radoman, 1973 is remarkably different from Lerniana because it bears a tubular shell, distinct shape and size of the seminal receptacles, and a penis with a wider base ( Radoman, 1983). Lerniana is more similar in shell shape to Turcorientalia Radoman, 1973 and Pseudorientalia Radoman, 1983 but differs from Graecorientalia Radoman, 1983 in having a larger and pyriform bursa copulatrix with a shorter duct, larger SR1 and narrower base of the penis; from Turcorientalia in terms of its smaller bursa copulatrix, larger seminal receptacles and longer and narrower penis; and from Pseudorientalia according to its narrower bursa copulatrix, larger seminal receptacles and narrower penis ( Radoman, 1983).

Figures

Figure 2. Majority-rule consensus tree from a Bayesian analysis based on the multilocus dataset (COI, 16S and 28S) of Radomaniola. Branch support values (BPP, Bayesian posterior probability; BS, bootstrap support) are provided on nodes. Tip labels correspond to the sequence codes given in the Supporting Information (Table S1). Vertical bars on the right represent entities identified by the molecular species delimitation methods automatic barcode gap discovery (ABGD), Bayesian generalized mixed Yule-coalescent method (bGMYC) and Poisson tree processes species delimitation method in a Bayesian framework (bPTP) and the multi-rate version (mPTP) with Bayesian support values. Scale bar below topology: substitutions per site.

Figure 3. Rate, correlation and mode of evolution of 40 traits along the Radomaniola phylogeny. A, time-calibrated phylogeny and trait distribution. Traits were scaled between 0.01 and 1 to display their variation among taxa. B, diagonal showing the Brownian motion rate of trait evolution and off-diagonals the pairwise evolutionary correlation. Modularity is suggested by a higher correlation within a functional organ (black square) than between two groups. Integration is indicated by a high or low within-group correlation. C, barplots showing, for each group of traits, the support [corrected Akaike information criterion (AICc) weight] for the modes of trait evolution.

Figure 7. Anatomy of Radomaniola curta montenegrensis subsp. nov. A–E, H, I, L, paratypes (UGSB 19515). F, G, J, K, UGSB 19043. A, ctenidium and osphradium. B, stomach. C, partial nervous system. D, F, pallial oviduct. E, G, bursa copulatrix and seminal receptacles. H, J, head of male and penis. I, K, penis. L, prostate gland.

Figure 9. Anatomy of Radomaniola curta omblensis subsp. nov. A–H, paratypes (UGSB 18778). A, ctenidium and osphradium. B, stomach. C, partial nervous system. D, pallial oviduct. E, bursa copulatrix and seminal receptacles. F, head of male and penis. G, H, penis. I, prostate gland.