Porcellionides molleri ( Verhoeff, 1901 )

Cifuentes, Julio & Da Silva, Luís P., 2024, Revision of the genus Porcellionides Miers, 1877 (Isopoda: Porcellionidae) in the Ibero-Balearic region, European Journal of Taxonomy 939, pp. 1-51 : 28-32

Porcellionides molleri ( Verhoeff, 1901)

Figs 2H, L , 3H , 15I–L , 19–20 , Table 1

Porcellio molleri Verhoeff, 1901: 406 .

Porcellionides variabilis Jackson, 1926: 187 , figs 23–43.

Porcellionides jacksoni Arcangeli, 1935: 21 .

Metoponorthus molleri – Verhoeff 1901: 406.

Material examined

PORTUGAL – Aveiro • 1 ♀; Serra do Bussaco ; 40.3619° N, 8.3550° W; 23 Dec. 2022; L.P. Da Silva leg.; LPS612 . – Bragança • 1 ♀; Mirandela ; 41.4758° N, 7.2184° W; 26 Jan. 2022; L.P. Da Silva leg.; LPS31 . – Coimbra • 1 ♀; Serra da Boa Viagem ; 40.1995° N, 8.9025° W; 26 Dec. 2022; L.P. Da Silva leg.; LPS634 . – Faro • 1 ♂; Cabo de Sagres ; 37.0010° N, 8.9475° W; 27 Dec. 2022; L.P. Da Silva leg.; LPS668 • 3 ♀♀; Cabo de São Vicente ; 37.0244° N, 8.9935° W; 27 Dec. 2022; L.P. Da Silva leg.; LPS646 • 1 ♀; Cabo de São Vicente ; 37.0245° N, 8.9936° W; 27 Dec. 2022; L.P. Da Silva leg.; LPS650 • 1 ♂; Pechão ; 37.0598° N, 7.8705° W; 29 Dec. 2022; L.P. Da Silva leg.; LPS705 . – Guarda • 1 ♂; Vila Nova de Foz Côa ; 41.0802° N, 7.1112° W; 27 Mar. 2023; L.P. Da Silva leg.; LPS750 . – Leiria • 1 ♀; Alvaiázere ; 39.8228° N, 8.4149° W; 8 Mar. 2022; L.P. Da Silva leg.; LPS132 • 1 ♀; Alvaiázere ; 39.8277° N, 8.4131° W; 8 Mar. 2022; L.P. Da Silva leg.; LPS133 • 1 ♂; Alvaiázere ; 39.8278° N, 8.4130° W; 8 Mar. 2022; L.P. Da Silva leg.; JC608 (ex. LPS 134) • 1 ♀; Alvaiázere ; 39.8280° N, 8.4129° W; 8 Mar. 2022; L.P. Da Silva leg.; LPS135 • 1 ♀; Alvaiázere ; 39.8352° N, 8.4114° W; 8 Mar. 2022; L.P. Da Silva leg.; LPS136 • 1 ♀; Alvaiázere ; 39.8283° N, 8.4073° W; 10 Jun. 2023; L.P. Da Silva leg.; LPS766 • 1 ♀; Alvaiázere ; 39.8298° N, 8.4127° W; 10 Jun. 2023; L.P. Da Silva leg.; LPS768 • 1 ♂; Alvaiázere ; 39.8243° N, 8.4136° W; 10 Jun. 2023; L.P. Da Silva leg.; LPS767 • 1 ♀; Alvaiázere ; 39.8229° N, 8.4148° W; 15 Mar. 2022; L.P. Da Silva leg.; LPS171 • 1 ♂; Arrimal ; 39.5074° N, 8.8822° W; 13 Mar. 2023; L.P. Da Silva leg.; LPS164 • 1 ♀; Arrimal ; 39.5074° N, 8.8821° W; 13 Mar. 2023; L.P. Da Silva leg.; LPS166 • 1 ♀; Arrimal ; 39.5076° N, 8.8827° W; 13 Mar. 2023; L.P. Da Silva leg.; LPS169 • 1 ♂; Praia de Salir do Porto ; 39.5068° N, 9.1485° W; 1 May 2022; L.P. Da Silva leg.; LPS306 • 1 ♀; Praia de Salir do Porto ; 39.5068° N, 9.1484° W; 1 May 2022; L.P. Da Silva leg.; LPS307 . – Viana do Castelo • 1 ♂; Castelo do Neiva ; 41.6203° N, 8.8080° W; 17 Dec. 2022; L.P. Da Silva leg.; LPS603a • 2 ♀♀; same collection data as for preceding; LPS603b • 2 ♂♂; Castelo do Neiva ; 41.6203° N, 8.8078° W; 17 Dec. 2022; L.P. Da Silva leg.; LPS604 • 2 ♂♂; Castelo do Neiva ; 41.6203° N, 8.8077° W; 17 Dec. 2022; L.P. Da Silva leg.; LPS605a • 2 ♀♀; same collection data as for preceding; LPS605b • 1 ♀; Foz do Neiva ; 41.6128° N, 8.8099° W; 17 Dec. 2022; L.P. Da Silva leg.; LPS602 .

SPAIN – Asturias • 1 ♂; Oviedo ; Barros leg.; MNCN 20.04/11853 . – Pontevedra • 1 ♂♂, 1 ♀, 2 immatures; La Guardia ; 3 Aug. 1985; J. Cifuentes leg.; JC237 • 1 ♂; same collection data as for preceding; JC637 • 1 ♂; same collection data as for preceding; JC638 • 1 ♂; same collection data as for preceding; JC639 • 17 ♂♂, 17 ♀♀; O Grove ; 6 Aug. 1953; W. Steiner leg.; col. Schmölzer; MNCN 20.04/9661 • 1 ♂; O Grove ; 18 Aug. 1953; W. Steiner leg.; coll. Schmölzer; MNCN 20.04/9631 .

All the specimens from Pontevedra province are cited by Cifuentes (2019).

Description

COLORATION. Highly variable coloration ( Fig. 19A–H ). Specimens range from nearly black to very light and even exhibit yellowish tones. Typically, darker cephalon than body. Pereon, in addition to mentioned color variations, with very marked muscular insertions and thin white-yellowish central line bordered by two dark lines. Pleonite epimera edge with elongated light patch bordered by two dark areas, more intense on insertion side and lighter on pleonite epimera side. Pleonite epimera more or less pigmented in anterior and posterior regions, but some individuals can be of yellowish-white color, intense red, or even dark brown. Pleon follows aforementioned color patterns, often with four dark lines, two central and two at neopleuron edges, which are variably pigmented. Pigmented telson with two light lateral spots. Light ventral side, with dark spot at basis of pereopods and pigmented pleopods. Antennae with dark segments, except second and third, which may be light brown, reddish, or whitish.

INTEGUMENTARY CHARACTERS. Very weak and flattened granulations ( Fig. 19A–H ). Glandular fields located at lateral edge of tergite, occupying almost its entire extent (Table I). Highly visible noduli laterales in small depigmented area, on first pereonites in posterior third and progressively closer to edge. Noduli laterales coordinates as in Figs 2H, L , 19I . Elliptical scales and scale-setae long and Y-shaped with sharp tip ( Fig. 3H ).

SOMATIC CHARACTERS. Cephalon with prominently curved frontal line, creating projection extending beyond small lateral lobes. Supra-antennal line distinctly marked. Pereon with posterior edge on first three pereonites rounded, while on pereonites IV–VII, small posterior tip gradually emerges. Tergites lack transverse ridges. Pleon more or less continuous with pereon, varying among specimens, but sometimes notably retracted. Short telson, with very small base and broad, triangular tip that barely surpasses the basipod of uropods ( Fig. 19A–H ).

APPENDAGES. Antennae barely reach posterior edge of third pereonite, although varies among specimens. Very small and rounded teeth on second and third segments, fourth segment lacks tooth. Carinated fourth and fifth segments. First flagellum segment approximately same length as second. Uropods with long and conical exopods in both sexes.

SEXUAL CHARACTERS. In males, carpus of pereopods 1 and 2 with a brush of long setae. Carpus of pereopod 1 with dense covering of scales on inner surface, in both sexes. Pereopod 7 without sexual differentiation. In males, endopod of pleopod I curves outward in posterior third, and triangular exopod with strongly curved inner edge and very small, pointed inner tip, with tracheal field with a notch ( Figs 15I , 19J ), also present in females ( Fig. 15K ). Male pleopod II with long and slender endopod and triangular exopod, very wide and long, with pronounced notch in tracheal field ( Figs 15J , 19K ). Less pronounced notch in females ( Fig. 15L ).

Remarks

Porcellionides molleri was described based on one male and three females collected from Coimbra. Later, Verhoeff (1918) improved the description and included an illustration of the male exopod of the pleopod I. Vandel (1962) and Schmalfuss (2003) classify it as a subspecies of P. sexfasciatus .

Arcangeli (1936), in his study on the isopods of Portugal, once again describes and illustrates what he refers to as Porcellio (Porcellionides) molleri ( Arcangeli 1936: 20, figs 8–12). However, as highlighted by Pollo Zorita (1982, 1986a), the three specimens examined by the Italian author actually belong to the species Porcellionides elegans . This determination is supported by the illustration of the male exopod of the pleopod I ( Arcangeli 1936: 20, fig. 11), which corresponds to the latter species ( Figs 4E , 6C).

Vandel (1946), in his study of the isopods of Portugal, presents a redescription of P. molleri , along with several figures. However, since the specimens we have analysed do not fully correspond with certain aspects of Vandel’s (1946) description, but do match the remaining characters of P. molleri , we believe it is beneficial to provide the above description of this species.

Porcellionides molleri can be distinguished from P. sexfasciatus by the granulations on its integument, the noduli laterales position, and the absence of a transverse ridge on the pereonites. In males, there is a brush of setae on the carpus of the pereopods I and II, while the exopod of the pleopod I lacks a posterior inner tip. Additionally, a tracheal field incision is present in this exopod, although it can be more or less pronounced. In the male exopod of the pleopod II, and female exopods of pleopods I and II, an incision is also present. These characters distinguish P. molleri from P. sexfasciatus , supporting our classification of P. molleri as a distinct and valid species.

Distribution

Only known from the westernmost area of the Iberian Peninsula, as records from the central part of Spain are likely to be identification errors ( Fig. 20 ). In Portugal it has been reported from the districts of Coimbra: Coimbra ( Verhoeff 1901); Faro: Serra de Monchique ( Vandel 1946); Leiria: Porto do Mós and Serra de Alvaiazera ( Vandel 1946); Lisboa: Monte Estoril by Jackson (1926), as Porcellionides variabilis Jackson, 1926 according to Vandel (1946) and by Arcangeli (1936) as Porcellionides jacksoni Arcangeli, 1936 according to Vandel (1946), and Sintra ( Vandel 1946; Schmölzer 1971); Setúbal: Beja ( Arcangeli 1936; Vandel 1946); Viseu: Serra do Caramulo ( Vandel 1946). In Spain it has been reported from the provinces of Cádiz: Sierra de la Luna ( Schmölzer 1955b); Ciudad Real: Venta de Cárdenas ( Schmölzer 1955a, this citation is likely an identification error); Coruña: Corrubedo, Noia, Punta de la Estaca and Santiago ( Schmölzer 1971); Lugo: Puente de Lozera ( Schmölzer 1955a); Orense: Castineira ( Schmölzer 1955a); Pontevedra: Bayona, Beluso ( Schmölzer 1971), Bueu ( Schmölzer 1955a), Cangas de Morrazo ( Schmölzer 1971), Gondomar, Isla de Ons ( Schmölzer 1971), La Guarda ( Cifuentes 2019), La Lamosa, Marín ( Schmölzer 1971), O Grove ( Cifuentes 2019), Pontevedra ( Schmölzer 1955a) and Ria de Vigo ( Schmölzer 1971).

Figures

Fig. 2. Relation between noduli laterales coordinates (following Vandel 1960) d/c (y-axis) and b/c (x-axis) multiplied by 100 for all studied species. A. Porcellionides cingendus (Kinahan, 1857). B. Porcellionides elegans(Pollo Zorita, 1982). C. Porcellionides fuscomarmoratus(Budde-Lund, 1885). D. Porcellionides glaber (Koch, 1856). E. Porcellionides hispanus (Vandel, 1953). F. Porcellionides lucasioides (Vandel, 1953). G. Porcellionides lusitanus (Vandel, 1946). H. Porcellionides molleri (Verhoeff, 1901). I. Porcellionides pruinosus (Brandt, 1833). J. Porcellionides sexfasciatus (BuddeLund, 1885). K. Porcellionides ibericus sp. nov. L. P. sexfasciatus and its previously considered subspecies: P. glaber (g), P. hispanus (h), P. lucasioides (l), P. lusitanus (lu), P. molleri (m) and P. sexfasciatus (s).

Fig. 3. Scale-setae. A. Porcellionides cingendus (Kinahan, 1857), ♂ (JC104). B. Porcellionides elegans (Pollo Zorita, 1982), ♂ (MNCN 20.04/7306). C. Porcellionides fuscomarmoratus (BuddeLund, 1885), ♀ (MNCN 20.04/8129). D. Porcellionides glaber (Koch, 1856), ♀ (MNCN 20.04/11490). E. Porcellionides hispanus (Vandel, 1953), ♂ (MNCN 20.04/7163). F. Porcellionides lucasioides (Vandel, 1953), ♂ (JC352). G. Porcellionides lusitanus (Vandel, 1946), ♂ (LPS661). H. Porcellionides molleri (Verhoeff, 1901), ♀ (LPS135). I. Porcellionides pruinosus (Brandt, 1833), ♀ (JC318). J. Porcellionides sexfasciatus (Budde-Lund, 1885), ♂ (LPS455a). Scale bar = 0.01 mm.

Fig. 15. Pleopods. A–D. Porcellionides lucasioides (Vandel, 1953). A–B. ♂ (JC648). A. Exopod I. B. Exopod II. C–D. ♀ (JC216). C. exopod I. D. Exopod II. E–H. Porcellionides lusitanus (Vandel, 1946). E–F. ♂ (LPS661). E. Exopod I. F. Exopod II. G–H. ♀ (LPS644). G. Exopod I. H. Exopod II. I–L. Porcellionides molleri (Verhoeff, 1901), ♂ (JC237). I. Exopod I. J. Exopod II. K. Exopod I. L. Exopod II.M–P. Porcellionides pruinosus(Brandt, 1833). M–N. ♂ (JC383). M. Exopod I.N. Exopod II. O–P. ♀ (JC42). O. Exopod I. P. Exopod II. Q–T. Porcellionides sexfasciatus (Budde-Lund, 1885). Q–R. ♂ (LPS455a). Q. Exopod I. R. Exopod II. S–T. ♀ (JC75). S. Exopod I. T. Exopod II. Scale bars = 0.1 mm.

Fig. 19. Porcellionides molleri (Verhoeff, 1901). A–H. Habitus. A. ♀ (LPS132). B. ♂ (LPS306). C. ♀ (LPS307). D. ♀ (LPS31). E. ♂ (JC639). F. ♀ (LPS135). G. ♀ (LPS136). H. ♂ (LPS604). I. Noduli laterales coordinates. J–K. ♂ (JC237). J. Exopod I. K. Exopod II. Scale bars: A–H = 1 mm; J–K = 0.1 mm.

Fig. 20. Localization of the Ibero-Balearic region in Europe and the distribution of Porcellionides molleri (Verhoeff, 1901).

Fig. 4. Pleopods. A–D. Porcellionides cingendus (Kinahan, 1857). A–B. ♂ (LPS215). A. Exopod I. B. Exopod II. C–D. ♀ (MNCN 20.04/11972). C. Exopod I. D. Exopod II. E–H. Porcellionides elegans (Pollo Zorita, 1982). E–F. ♂ (JC490). E. Exopod I. F.Exopod II. G–H. ♀ (MNCN 20.04/9590). G. Exopod I. H. Exopod II. I–L. Porcellionides fuscomarmoratus (Budde-Lund, 1885). I–J. ♂ (UGMSS-2). I. Exopod I. J. Exopod II. K–L. ♀ (MNCN 20.04/8129. K. Exopod I. L. Exopod II. M–P. Porcellionides glaber (Koch, 1856). M–L. ♂ (MNCN 20.04/7886). M. Exopod I. N. Exopod II. O. ♀ (MNCN 20.04/11490), exopod I. P. ♀ (MNCN 20.04/11490), exopod II. Q–T. Porcellionides hispanus (Vandel, 1953). Q–R. ♂ (MNCN 20.04/7163). Q. Exopod I. R. Exopod II. S–T. ♀ (JC380). S. Exopod I. T. ♀ (JC380), exopod II. Scale bars = 0.1 mm.