Porcellionides lusitanus
Creators: name: Cifuentes, Julio
name: Da Silva, Luís P.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Isopoda
Porcellionidae
Porcellionides
Porcellionides lusitanus

description: Porcellionides lusitanus (Vandel, 1946)
Figs 2G, L, 3G, 15E–H, 17–18, Table 1
Metoponorthus sexfasciatus lusitanus Vandel, 194: 269, figs 80, 84–85.
Material examined
PORTUGAL – Faro • 1 ♀; Cabo de São Vicente; 37.0245° N, 8.9935° W; 27 Dec. 2022; L.P. Da Silva leg.; LPS644 • 1 ♂; Cabo de São Vicente; 37.0240° N, 8.9946° W; 27 Dec. 2022; L.P. Da Silva leg.; LPS661 • 1 ♀; same collection data as for preceding; JC774 (ex. LPS664) • 1 ♂; Cabo de São Vicente; 37.0240° N, 8.9942° W; 27 Dec. 2022; L.P. Da Silva leg.; LPS662 • 1 ♂; Cabo de São Vicente; 37.0241° N, 8.9944° W; 27 Dec. 2022; L.P. Da Silva leg.; LPS663a • 1 ♀; same collection data as for preceding; LPS663b • 1 ♂; Cabo de São Vicente; 37.0241° N, 8.9945° W; 27 Dec. 2022; L.P. Da Silva leg.; LPS665 • 1 ♀; Fonte da Benémola; 37.2041° N, 8.0037° W; 30 Dec. 2022; L.P. Da Silva leg.; LPS718 • 1 ♂; Faro, Gambelas; 37.0420° N, 7.9715° W; 29 Dec. 2022; L.P. Da Silva leg.; JC775 (ex. LPS694a) • 1 ♀; same collection data as for preceding; LPS694b.
Remarks
In 1946, Vandel described a new subspecies of P. sexfasciatus, designating it M. sexfasciatus lusitanus, which is now recognized as P. sexfasciatus lusitanus (Vandel, 1946). This description was based on 2 males and 14 females collected from different locations throughout Portugal, in addition to 35 specimens obtained from the Mamora forest, in Morocco. Unfortunately, some of his illustrations lack a reference to the capture locations. He indicates that P. lusitanus is more variable than other subspecies. However, it differs from P. sexfasciatus in several characters, namely: its larger size, reaching 13 mm in females; much stronger granulations, including those located on the posterior edge of pereonites and pleonites; elongated antennae, with the first segment of the flagellum much longer than the second; in males, the pereopod 1 lacks a brush of setae, except in large males from Morocco; the shape of the exopod is highly variable, as illustrated by various figures (Vandel 1946: 266, fig. 80b–d).
The specimens we analysed, measuring up to 12 mm in males (14 mm including uropods) and 13 mm in females (14.2 mm including uropods), closely align with Vandel’s description, although showing some important nuances. The coloration is dark brown with lighter muscle insertions (Fig. 17A–B). On the cephalon, the frontal line forms a slight curve, while the lateral lobes are well defined (Table 1). The tergites lack transverse ridges; however, a line of granulations occupies the area where transverse ridges are typically found in other species. The b/c and d/c coordinates are consistently lower compared to those in P. sexfasciatus (Figs 2G, L, 17C). The scale-setae are triangular and wide (Fig. 3G). In males, the carpus of the pereopod I has a brush of setae, while the exopod of the pleopod I exhibits only a small, rounded posterior inner tip (Figs 15E, 17D) and a sinuous tracheal field. The male exopod of the pleopod II also exhibits a sinuous tracheal field (Figs 15F, 17E), similar to that of both female exopods (Fig. 15G–H).
Therefore, P. lusitanus presents important distinguishing characters that differentiate it from P. sexfasciatus, thus confirming its status as a valid species. The variability mentioned by Vandel (1946) in P. lusitanus could be attributed to the inclusion of specimens from other species. For example, the specimens identified by Vandel (1946) as P. s. lusitanus, which lack sexual differentiation in the pereopods and exhibit a long and slender posterior inner tip on the exopod of the pleopod I in males, are likely P. glaber, while those specimens that do exhibit sexual differentiation in the pereopods and have a short and rounded posterior inner tip on the exopod of the pleopod I are P. lusitanus.
Distribution
The subsequent authors who have studied the isopod fauna of the Iberian-Balearic region, following Vandel (1946), have reported P. sexfasciatus lusitanus in various districts in Portugal and provinces in Spain. However, we observed this species exclusively within the Portuguese district of Faro (Fig. 18). Many of the occurrences in the northern Iberian Peninsula are likely to represent P. molleri, as discussed below. Similarly, some records from the southern region may also represent other species within the Porcellionides genus.
Vandel (1946) suggests that the P. sexfasciatus recorded by Preudhomme De Borre (1886) likely corresponds to P.sexfasciatus lusitanus. However, this suggestion remains doubtful because Preudhomme De Borre only made reference to a single specimen captured in Mafra. Cruz (1991) documented the presence of P. sexfasciatus lusitanus in Cádiz (Villaluenga del Rosario and Vejer de la Frontera) and Málaga (Pozuelo Montejaque). After conducting a thorough examination of the specimens within A. Cruz’s collection deposited at the Centre de Recursos de Biodiversitat Animal de la Universitat de Barcelona (CRBA), we have confirmed they are indeed P. glaber. Similarly, the references provided by Cifuentes (2021a) for Cádiz (Algeciras, Arcos-Bornos, Puerto Real, Tarifa, Vejer de la Frontera), Huelva (Alájar, Cala, Doñana), and Málaga (Benaoján, Puerto del Pozuelo) also correspond to P. glaber. Vandel (1946) has reported occurrences in the districts of Faro (Algueiráo, Mexilhoerinha, Pic de Foia, Pic de Picota) and Beja (Sobral da Adiça), which we consider to be valid. However, we recommend reviewing the records of Vandel (1946) from Porto (Ermezinde, Sao Pedro da Cova), as well as those of Gregory et al. (2012) from Viana do Castelo (Vila Praia de Âncora). In Spain, the following records should also be revised: Schmölzer (1955a) from Madrid (El Escorial) and later (Schmölzer 1971) from Coruña (Bahía de Corme, Noia) and Pontevedra (Bayona, Gondomar, Cies Island, Ons Island, Lourido), records that are likely to be misidentifications; Gregory et al. (2012) recorded its occurrence in Pontevedra (Camposancos), and Garcia (2019) recorded its presence in Huelva (Huelva).
description: Published as part of Cifuentes, Julio & Da Silva, Luís P., 2024, Revision of the genus Porcellionides Miers, 1877 (Isopoda: Porcellionidae) in the Ibero-Balearic region, pp. 1-51 in European Journal of Taxonomy 939 on pages 25-28, DOI: 10.5852/ejt.2024.939.2573, http://zenodo.org/record/12156988