Iberhoratia aurorae, Arconada & Delicado & Ramos, 2007

Arconada, Beatriz, Delicado, Diana & Ramos, M. Ángeles, 2007, A new genus and two new species of Hydrobiidae (Mollusca, Caenogastropoda) from the Iberian Peninsula, Journal of Natural History 41 (29 - 32), pp. 2007-2035 : 2019-2025

Iberhoratia aurorae new species

( Figures 5–7 )

Type locality

Spring between Hervás and Jerte, Cáceres, UTM: 30TTK551596 .

Material examined

Type material. Holotype: MNCN 15.05 /46991 ( SEM preparation, Figure 5F, H, J, K ) . Paratypes: MNCN 15.05 /46991 (ethyl alcohol) .

Other populations examined. This species was found in the provinces of Cáceres , Salamanca , and Toledo ( Figure 1 ). Localities are the following: spring between Hervás and Jerte, Cáceres (type locality), 10 June 1989, E. R., MNCN 15.05 /46991 (ethyl alcohol, SEM preparation); stream in Roturas, Cáceres, UTM: 30STJ8482, 30 March 1991, E. R., MNCN 15.05 /46992 (ethyl alcohol, SEM preparation); stream in Sierra Altamira, Toledo, UTM: 30SUJ29, 29 March 1991, E. R., MNCN 15.05 /46993 (ethyl alcohol); Béjar, Salamanca, UTM: 30TTK6573, 10 June 1989, E. R., MNCN 15.05 /46994 (ethyl alcohol) .

Material examined for morphometry. Shell measurements (Table I) correspond to specimens from all above populations. Operculum and radular measurements (Table II, IV) correspond to the type locality. Anatomical measurements (Tables III, IV, VI, VII) correspond to the type locality, Roturas , Béjar , and Sierra de Altamira. Males and females studied and measured were collected in March and June .

Etymology

Dedicated to Aurora López, mother of the first author.

Diagnosis

Shell valvatiform; operculum oval without peg; the oesophagus makes a loop near the cerebral commissure; rectum strongly S-shaped; male genitalia with a slender penis having a non-glandular penial lobe located in a medial position; female genitalia with a pallial oviduct with a marked narrowing, an oval, well-developed bursa copulatrix and two seminal receptacles; distal seminal receptaculum rounded and proximal one lying over the renal oviduct; central tooth of the radula with one basal cusp on each side.

Description

Shell valvatiform ( Figure 5A–F ; Table I), with 3.5 whorls, approximately; 1.25 protoconch whorls, total width and nucleus width are 304 and 126 Mm, respectively ( Figure 5H, I ); protoconch microsculpture with granules ( Hershler and Ponder 1998, p 4) ( Figure 5J, K ); some specimens have been found with an eroded protoconch near the varix which separates it from the teleoconch ( Figure 5I ); umbilicus wide, 0.28 Mm in diameter ( Figure 5G ); aperture rounded-oval; outer peristome simple, thin, and straight ( Figure 5D ).

Operculum thin, pliable, corneous, paucispiral, oval, yellowish, with a large and central nucleus ( Figure 6A, B ; Table II); its muscle attachment area is oval, generally submarginal but sometimes almost central.

Body: head unpigmented or scarcely pigmented around the eyes ( Figure 7F ). Snout about as long as wide, parallel-sided, with a medium distal lobation.

Nervous system with a suboesophageal connective absent and a long supraoesophageal connective ( Figure 7B ); the oesophagus makes a loop to the right posterior to the cerebral commissure ( Figure 7A ); nervous system measurements are: length of the cerebral ganglia: 0.16 mm; length of the right pleural ganglion: 0.14 mm; length of the left pleural ganglion: 0.14 mm; length of the suboesophageal ganglion: 0.07 mm; length of the supraoesophageal ganglion: 0.11 mm; length of the pleurosupraoesophageal connective: 0.14 mm; RPG ratio is 0.35.

Ctenidium with 11–13 well-developed lamellae, occupying around two-thirds of the pallial cavity ( Figure 7C ); osphradium 50–60% of ctenidium length, oval, two to three times longer than broad, located in the opposite middle of the ctenidium (Table III).

Stomach with posterior and anterior chambers approximately equal in size ( Figure 7E ); rectum strongly S-shaped ( Figure 7D ); the length of the style sac is around three-fifths of the length of the stomach (Table V).

Radula taeniaglossate ( Figure 6C–F ; Table IV), long (0.5%) relative to maximum shell dimension; central trapezoidal tooth with one basal cusp on each side; distance between internal cusps is 7 Mm, approximately; its central denticle is long and tapered, followed on each side by four to five similar denticles in decreasing order of size; basal tongue Vshaped; cutting edge of the central tooth markedly excavated; lateral teeth with four to six denticles on each side of the central one; marginal teeth with abundant small and sharp denticles.

Male genitalia with a small, bean-shaped prostate gland (Table VI); the anterior lobes of the testis overlaps the posterior chamber of the stomach, sometimes reaching the anterior chamber; penis slender, with distal end tapered, shorter than the head, with an unpigmented non-glandular penial lobe located in a medial position ( Figure 7F ); the penis is black pigmented near its tip; penial duct runs straight near the outer edge of the penis.

Female genitalia with a renal oviduct making a tight circle which leans over the albumen gland ( Figure 7G ); bursa copulatrix oval, almost rectangular, protruding posterior to albumen gland, well developed ( Figure 7G, H ), with a long duct; origin of bursal duct anteroventral; proximal seminal receptacle (SR2) lying tightly over the widened part of the renal oviduct ( Figure 7H ); most of the females have a large and rounded distal seminal receptacle (SR1), with a very short, or not evident, stalk located at or next to the area where the bursal duct arises from the renal oviduct ( Figure 7H ); oviduct glands (albumen + capsule glands) slender, with a marked narrowing in its middle part ( Figure 7G ). This narrowing is produced by the strong folding of the rectum in the pallial cavity constraining the pallial oviduct; capsule gland is larger than the albumen gland (Table VII).

The SR1 appears like an off-white and refringent ball in some populations, while in others it can be observed as a large and almost transparent vesicle inside of which a smaller and off-white vesicle can be distinguished arising from the SR basis.

Remarks

The granulated protoconch microsculpture of Ib. aurorae is different from that of Ib. morenoi and the rest of the known Iberian Hydrobiidae species. There is very low variability between populations of this species. Comparing the type locality with the other populations examined, shells are smaller and more flattened, thus showing lower values in all shell parameters, except for the ratio of shell length/shell width. Number of whorls is also higher in the type locality. Other anatomical measurements show similar range variability, although very few specimens were available for comparisons. Several females studied from Roturas populations were infected with parasitic trematodes in different larval stages. The bursa copulatrix, pallial oviduct, and seminal receptacle were almost indistinguishable in these specimens. Castration induced by parasites and the role of intermediate hosts in some parasite cycles has already been described in other gastropods ( Rothschild 1938; González- Moreno et al. 1994). These parasites have also been found infecting the whole body of females. Shells from the Altamira population are reddish, probably due to external metal deposition. On the contrary, shells from Bejar and Hervás–Jerte populations are transparent.

Figures

Figure 1. Iberian Iberhoratia populations.

Figure 5. Shells of Iberhoratia aurorae. (A–D, G) Shells from Robladillo de Gata; (E, I) shells from Roturas; (F, H, J, K) shell (holotype) from population between Hervás and Jerte (type locality). (H–K) Protoconch and microsculpture. Scale bar: 500 Mm (A–G).

Figure 6. Operculum and radula of Iberhoratia aurorae from type locality. (A) Internal side of the operculum; (B) external side of the operculum; (C) radula; (D) central and lateral teeth; (E) central tooth; (F) lateral and internal marginal teeth. Scale bar: 200 Mm (A, B); 100 Mm (C).

Figure 7. Anatomy of Iberhoratia aurorae from type locality. (A, B) Partial nervous system; (C) osphradium and ctenidium; (D) rectum curve; (E) stomach; (F) head of a male and penis; (G) anterior female genitalia; (H) bursa copulatrix and seminal receptacles. Abbreviations in text. Scale bar: 500 Mm (A–H).