Odontophrynus, Reinhardt and Lutken, 1862
|
publication ID |
https://doi.org/ 10.1016/j.jcz.2022.09.004 |
|
persistent identifier |
https://treatment.plazi.org/id/03AA7508-FFA7-1D31-8801-DC592C960143 |
|
treatment provided by |
Felipe |
|
scientific name |
Odontophrynus |
| status |
|
3.1. Protuberances in the genus Odontophrynus View in CoL
The postorbital, temporal and parotoid protuberances of the studied species of the genus Odontophrynus have macroscopic differences in size and shape, especially between the species of the O. americanus group, the species of O. cultripes group, and O. occidentalis ( Fig. 2A–C View Fig ; Table 1). Conversely, the studied protuberances are histologically similar ( Fig. 2 View Fig D-L) but differ from dorsal skin ( Fig. 2 View Fig MO) respect to the organization of the dermis, the size of the syncytial glands, and the arrangement of these glands in each region ( Table 2). No differences between sexes are observed.
The epidermis of the examined regions has 3–5 layers of cells, depending on the species ( Table 1). It is divided in a basal layer with cylindrical cells corresponding to the stratum germinativum, a stratum intermedium with 2–3 layers of polyhedral cells and, more externally, the stratum corneum with a single layer of flat, highly keratinized cells ( Fig. 3A–B View Fig ). Images of SEM show that the superficial epidermal cells have well-defined boundaries and a distinctive reticulation ( Fig. 1B–C View Fig ). In most species, scattered blunt spines are observed both on the surface of protuberances and dorsal skin ( Fig. 3C View Fig ). These spines are formed by an increase in the thickness of the stratum intermedium, with superficial keratinized cells of the stratum corneum arranged like a rosette ( Fig. 3B, D View Fig ). In general, the size of the spines varies between 12.4 and 19.8 μm height and 22.7–36.4 μm width. However, while specimens of O. occidentalis from C´ordoba and San Luis have considerably larger spines (37.9 μm height and 78.7 μm width), specimens of O. occidentalis from La Rioja and Mendoza, have a smooth skin, without spines ( Table 1).
In the species of the O. americanus group, the stratum spongiosum of the dermis consists of loose connective tissue. Dermal glands are arranged in this stratum spongiosum and the subjacent stratum compactum is formed by dense connective tissue ( Fig. 2D, G, J, M View Fig ). The dermis in the two studied regions has the same histological organization. In contrast, topographical staining of skin sections of O. carvalhoi ( O. cultripes group) shows only one stratum of dense connective tissue in the dermis, both in the protuberances as in the dorsal region ( Fig. 2F, I, L, O View Fig ). Though, the von Kossa technique which stains the Eberth-Kastschenko (EK) layer that divides the two dermal strata, evidences a thin stratum spongiosum that contains the secretory portion of the alveolar glands ( Fig. 4A View Fig ). The subjacent stratum compactum contains the secretory portions of the syncytial glands ( Fig. 4A View Fig ). Regarding specimens of O. occidentalis (La Rioja and Mendoza), the dermis of the protuberances and dorsal skin have the same histological characteristics as that described for the O. americanus group ( Fig. 2E, H, K, N View Fig ). In contrast, the protuberances in O. occidentalis (C´ordoba and San Luis) have a homogeneous dense connective tissue with no division between the two dermal strata ( Fig. 4B View Fig ).
The EK layer in O. americanus , O. reigi ( O. americanus group) and O. carvalhoi ( O. cultripes group) is thin and discontinuous in all examined regions ( Fig. 4A View Fig ). In O. cordobae ( O. americanus group) and O. occidentalis (La Rioja and Mendoza), this layer is not evident in the protuberances but it is present in the skin of the dorsal region ( Fig. 4C View Fig ). In contrast, as previously mentioned, O. lavillai ( O. americanus group) and O. occidentalis (C´ordoba and San Luis) lack the EK layer ( Table 1).
Regarding the alveolar glands (AGs) in the dermis of protuberances and dorsal skin ( Fig. 2 View Fig D-O), they have a circular pore ( Fig. 1B View Fig ), with a duct and neck lined by a simple squamous epithelium ( Fig. 5A View Fig ). The secretory portion consists of a simple cylindrical or cuboidal epithelium, depending on the activity of the secretory cells, which lines a large lumen ( Fig. 5A–D View Fig ). These cells have an ovoid basal nucleus ( Fig. 5A–B, D View Fig ) and the secretion has a spongy ( Fig. 5B View Fig ) and/or granular appearance ( Fig. 5A View Fig , C-D; Table 2). In most studied species, the AGs secretion shows acidic ( Fig. 5A View Fig ) and neutral ( Fig. 5D View Fig ) glycoconjugates and proteins ( Fig. 5E View Fig ). Exceptions are O. reigi ( O. americanus group) and O. carvalhoi ( O. cultripes group) in which the secretion of the AGs is not alcyanophilic ( Tables 3 and 4). Excluding O. americanus and O. lavillai ( O. americanus group), the secretion of the AGs is also lipidic ( Fig. 5F View Fig ; Table 2).
The syncytial glands (SGs) of the dorsal skin differ from those of the protuberances mainly in size. The SGs in the protuberances are twice as high as those in the dorsal skin, corresponding to large syncytial glands (LSGs). The small size SGs are the ordinary syncytial glands (OSGs) and are only observed in the dorsal skin ( Tables 2 and 3). Regarding the chemical nature and morphology of the secretion, in most species, the LSGs and OSGs have the same characteristics, except for the protuberances of O. lavillai , O. reigi ( O. americanus group) and O. occidentalis (La Rioja) ( Tables 2 and 3). Furthermore, excepting O. reigi , LSGs in the protuberances are closely packed ( Fig. 2 View Fig D-L and 6 A-B; Table 3). In this species, the closeness of LSGs is partial, due to the presence of connective tissue between the secretory portion ( Fig. 6C–D). Differently, the Measurements as mean ±SD (in μm). Abbreviations: M = Major pore diameter, m = Minor pore diameter.
OSGs in the dorsal skin are scattered in all the species ( Fig. 2M O View Fig ).
For all the studied species, LSGs and OSGs are characterized by having a stoma-like pore ( Fig. 1A View Fig ; Table 4). O. americanus , O. cordobae , O. reigi ( O. americanu s group), O. carvalhoi ( O. cultripes group) and O. occidentalis (Mendoza) have large pores, with a mean major diameter of 19.5 μm and a mean minor diameter of 14.5 μm, and small pores, with a mean major diameter of 11.5 μm and a mean minor diameter of 8 μm ( Table 4). The secretory portion in both types of syncytial glands communicates with the pore through a secretory duct and neck ( Fig. 6E), which are lined by a bistratified epithelium with a basal cell layer with ovoid nuclei. The superficial cell layer is highly keratinized in the duct but has cubical cells with rounded nuclei in the neck ( Fig. 6F). An exception to this is the neck of the LSGs of O. occidentalis (La Rioja and Mendoza), where the epithelium has more than two cell layers. In longitudinal sections, with respect to the neck, it is possible to observe a small central opening ( Fig. 6E).
A thin layer of cells with flat nuclei, which correspond to myoepithelial cells, surrounds externally the secretory portion of the LSGs and OSGs. Internally, the secretory portion is lined by a thin syncytium with ovoid nuclei ( Fig. 6E, G). The lumen of these glands is completely occupied by basophilic granules immersed in an acidophilic matrix ( Fig. 6E–H; Tables 2 and 3). The secretion of all SGs does not contain acidic glycoconjugates ( Tables 2 and 3). Protuberances of O. americanus , O. lavillai , O. reigi ( O. americanus group) and O. occidentalis (C´ordoba, La Rioja and San Luis) have two types of syncytial glands, which differ in morphology and chemical nature of the secretion ( Fig. 6I–J; Tables 2 and 3). Two types of SGs in the dorsal skin are only observed in O. americanus and O. occidentalis (Cordoba ´and San Luis) ( Table 2).
All studied species, except O. cordobae ( O. americanus group), have at least one type of SG with a protein-rich secretion ( Fig. 6K). Syncytial glands of O. cordobae , O. lavillai , O. reigi ( O. americanus group) and O. occidentalis (La Rioja) also possess lipidic secretion ( Fig. 6B). In those species with Sudan Black positive SG, the secretion turns greenish, which may be due to the mixing of the black colour of the dye with the natural yellowish colour of the secretion ( Fig. 6B). The SGs in O. cordobae , O. lavillai , O. reigi ( O. americanus group) and O. carvalhoi ( O. cultripes group) have a neutral glycoconjugates-rich secretion ( Fig. 6L; Tables 2 and 3).
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.