Visual pigments in the regressed eye and pineal of the depigmented neotenic urodele, the blind cave salamander (Proteus anguinus anguinus), were studied by immunocytochemistry with anti-opsin ...antibodies. The study included light- and electron-microscopic investigations of both the eye and the pineal organ. A comparison was made with the black pigmented subspecies Proteus anguinus parkelj (black proteus), which has a normal eye structure. In the retina of the black proteus, we found principal rods, red-sensitive cones and a third photoreceptor type, which might represent a blue- or UV-sensitive cone. Photoreceptors in the regressed eye of the blind cave salamanders from the Planina cave contained degenerate outer segments, consisting of a few whorled discs and irregular clumps of membranes. The great majority of these outer segments showed immunolabelling for the red-sensitive cone opsin and only a few of them were found to be positive for rhodopsin. An even more pronounced degeneration was observed in the photoreceptors of the animals derived from the Otovec doline, which are completely devoid of an outer segment, most of them not even possessing an inner segment. Even in some of these highly degenerate cells, the presence of rhodopsin could be detected in the plasma membrane; however, immunoreactions with antibodies recognizing cone visual pigment were negative. In the pineals of all studied animals, the degenerate photoreceptor outer segments were recognized exclusively by the antibody against the red-sensitive cone opsin. The presence of immunopositive visual pigments indicates the possibility of a retained light sensitivity in the blind cave salamander photoreceptors.
Niphargus steueri (Niphargidae) comprises a complex of four subspecies (N. s. steueri, N. s. kolombatovici, N. s. subtypicus, and N. s. liburnicus), the morphology and distribution of which have been ...poorly known until now. New diagnostic characters of the species and its four subspecies are presented and illustrated. The species is distributed along the major part of the Dinaric Karst, between Slovenia in the northwest and Bosnia and Herzegovina in the southeast. The distribution of the four subspecies approximately resembles the distribution of the evolutionary lineages of the subterranean amphibian Proteus anguinus and the Dinaric lineage of the cave shrimp Troglocaris agg. anophthalmus. Niphargus s. steueri is restricted to the Istran Peninsula; N. s. subtypicus is distributed in southeast Slovenia and northwest Croatia; N. s. liburnicus is known from two disjunctive localities, one on the island of Krk (Croatia) and the other in Gorizia (Italy); and N. s. kolombatovici is restricted to Dalmacija and Herzegovina. The somewhat variable putative synapomorphies of N. steueri probably suggest that the group is old and that the present distribution pattern is a result of historical events, possibly events in the Miocene Dinaride Lake system. Two populations of N. s. kolombatovici and one population of N. s. subtypicus deviate from the general distributional pattern and may belong to cryptic taxa that cannot be distinguished on the basis of morphology. Both hypotheses corroborate with the estimated times of divergence and with the number of independent lineages in the similarly distributed but unrelated stygobionts Proteus and Troglocaris.
Cloacae from male Proteus anguinus were examined for the first time by light and electron microscopy. Male P. anguinus possess anterior and posterior ventral glands, dorsal and lateral pelvic glands, ...vent glands and Kingsbury's glands as do Necturus males. However, male P. anguinus also possess the new additional cloacal glands found in females and which the author has called the ventral skin glands. Furthermore, the number, the length and the diameter of these tubular glands are higher in males. Therefore the inference is that these glands are sexually dimorphic glands.
Cloacae of female Proteus anguinus were examined by light and electron microscopy. Females possess spermathecae and anterior ventral glands such as Necturus females. However, female P. anguinus ...possess new additional cloacal glands of unknown homology. These tubular glands secrete on the ventral epidermis of the cloacal area. Considering these characteristics, it is proposed that they will be called the ventral skin glands.
We studied ultrastructure of the photoreceptor cells in the pineal organ of blind, depigmented, neotenic cave salamander, Proteus anguinus. Unlike in epigean vertebrates the outer segments of most ...photoreceptor cells consists of concentrically arranged lamellae, however; in few cells, the outer segments contain 7-9 plasma membrane disks. In both types of photoreceptor cells the outer segments enclose lumps of vesicles of different sizes. The photoreceptor cells of Proteus anguinus are similar to those in other cavernicolous fish species.
Octavolateral sensory organs (auditory and lateral line organs) of cave salamander Proteus anguinus are highly differentiated. In the saccular macula of the inner ear the complex pattern of hair cell ...orientation and the large otoconial mass enable particle displacement direction detection. Additionally, the same organ, through air cavities within the body, enables detection of underwater sound pressure changes thus acting as a hearing organ. The cavities in the lungs and mouth of Proteus are a resonators that transmit underwater sound pressure to the inner ear. Behaviourally determined audiograms indicate hearing sensitivity of 60 dB (rel. 1 µPa) at frequencies between 1 and 10 kHz. The hearing frequency range was between 10 Hz and 10 kHz. The hearing sensitivities of depigmented Proteus and black Proteus were compared. The highest sensitivities of the depigmented animals (N=4) were at frequencies 1.3-1.7 kHz and it was 2 kHz in black animals (N=l). Excellent underwater hearing abilities of Proteus are sensory adaptations to cave habitat.
The concentrations of some essential (Cu, Zn, Se) and some toxicelements (Hg, As) were determined in tissues (liver, kidneys, integument, and muscle) of the endemic cave salamander, Proteus anguinus ...Laurenti 1768 and Proteus anguinus parkelj ssp.n. captured in the Planina Cave, Kompolje Cave, and Jelsevnik, all situated within the Dinaric Karst in Slovenia. The highest amounts of selenium and mercury were found in the liver of Proteus anguinus specimens from all three localities. Some of the animals from the Planina Cave showed higher concentrations of copper in the liver and muscle. Pigmented subspecies of Proteus from Jelsevnik showedincreased values of arsenic in the integument and of zinc in theliver and integument. The liver of the animals contained the highest amounts of the metals analysed and therefore may be considered as a target organ. Metal levels were also measured inthe cave water and sediments. The waters were not polluted withmetals. However, the metals were relatively high in the sediments, but not to levels considered contaminated. In additionto our study of metal concentrations in Proteus tissues andhabitats, several water quality parameters were measured in the water of each locality. The main differences between the threelocalities concerned dissolved oxygen concentration and saturation, while all other physical and chemical parameterswere characteristic of the aquatic environment in the calcareousKarst region.PUBLICATION ABSTRACT
The presence of metallothionein (MT) and the subcellular distribution of copper, zinc and cadmium were investigated in livers of two neotenic salamanders,
Proteus anguinus and
Necturus maculosus. In
...P. anguinus, caught in the wild, hepatic MTs were present as a single isoform of (Zn, Cu, Cd)-thioneins, whose molecular weight was estimated to be approximately 12
000 by size exclusion chromatography. The percentage of zinc and cadmium was higher in the cytosol and of copper in the pellet. Cytosolic cadmium was almost exclusively associated with MTs (80%), while zinc and copper were also present in the regions of higher-molecular weight proteins. In laboratory bred
N. maculosus, MTs were isolated from the liver cytosol and extract of the pellet as (Cu, Zn)- and (Zn, Cu)-thioneins, respectively. According to the low amount of copper extracting from liver pellets of
N. maculosus, the presence of water insoluble aggregated forms of Cu-thioneins should be checked in further investigations.
Morphometric data for the cave salamander, Proteus anguinus, from the Dinaric Karst of south‐eastern Europe are analysed with data for the recently described black and non‐troglomorphic Proteus ...anguinus parkelj from south‐eastern Slovenia. Proteus a. anguinus and P. a. parkelj are morphologically distinct. Within P. a. anguinus, inland and coastal populations possess distinguishable phenotypes. Mantel permutation tests show that no firm evidence is available that demonstrates the existence of clinal variation. The characters that best describe differences within P. a. anguinus (head, trunk and tail length, the number of costal grooves) also document the differentiation between P. a. anguinus and P. a. parkelj. The claim that P. a. parkelj falls within the (clinal) variation of P. a. anguinus is untenable. Accordingly, its taxonomic status is upheld.
