Armadillidium boalense, Cifuentes & Robla & Garcia, 2024

Cifuentes, Julio, Robla, Jairo & Garcia, Lluc, 2024, Description of Armadillidium boalense sp. nov. from northern Spain, with remarks and a key of the genus in the Iberian Peninsula and the Balearic Islands (Isopoda: Oniscidea: Armadillidiidae), Zootaxa 5497 (1), pp. 83-99 : 84-91

publication ID	https://doi.org/ 10.11646/zootaxa.5497.1.4
publication LSID	lsid:zoobank.org:pub:7F924C76-CE6D-4F31-9020-400800FAE279
DOI	https://doi.org/10.5281/zenodo.13685714
persistent identifier	https://treatment.plazi.org/id/75271B99-356E-4CCA-BAB0-B6419AF94AB3
taxon LSID	lsid:zoobank.org:act:75271B99-356E-4CCA-BAB0-B6419AF94AB3
treatment provided by	Plazi
scientific name	Armadillidium boalense
status	sp. nov.

Treatment

Armadillidium boalense sp. nov.

Figs 2–6 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6

Diagnosis. An Armadillidium species with conglobation ability of eusphaeric type. Head of duplocarinate type, with scutellar and post-scutellar ridges. Dorsum smooth. Cuticular structures characterized by circular cavities and sharp scale-setae. Pleotelson triangular with rounded tip. Male pereopod 7 strongly differentiated on ischium, merus and carpus. First male pleopod with endopod straight, three times as long as the exopod, not narrowed, slightly bent apically; pleopod 1–2 exopod notched on outer margin of tracheal field, both in males and females.

Etymology

The name of the species comes from Boal (municipality of Asturias, Spain) ( Fig. 1A View FIGURE 1 ) which is the area where the specimens were collected.

Material examined

Holotype: Spain • ♂; Asturias, Boal, As Cabanas (Os Chaos); 43º25′40.02′′ N, 6º48′18.63′′ W; 470 m a.s.l.; 20 Mar. 2023; G. Sánchez Jardón leg.; hand collected under stones of a granitic wall embedded; MNCN 20.04 About MNCN /20717. GoogleMaps

Paratypes: Spain • 5♂; same collection data as for holotype; MNCN 20718-22 About MNCN GoogleMaps • 4♀; same collection data as for holotype; MNCN 20723-26 About MNCN GoogleMaps • 2♂; same collection data as for holotype; MBCN 26863 and GoogleMaps MBCN 26864 GoogleMaps • 1♂ dissected and mounted into preparations; same collection data as for holotype; CLLG 1187 GoogleMaps • 2♀; same collection data as for holotype; MBCN 26865 and GoogleMaps MBCN 26866 GoogleMaps • 1♀ partially dissected; same collection data as for holotype; CLLG 1187 B GoogleMaps . • 2♂; same collection data as for holotype; CJC708 and GoogleMaps CJC709 GoogleMaps • 1♀; same collection data as for holotype; CJC710 GoogleMaps .

Description

Body. Measurements. Maximum length observed 6.5 x 2.8 mm (male). Colour. Dark purplish brown ( Figs. 2A–B View FIGURE 2 , 3A–C View FIGURE 3 ), with yellow muscle spots disposed as follows: pereon -tergites with two paramedian large spots, lateral smaller spots more or less fused; pereon-epimera with small spots except on sevenths; pleon-tergites with some small paramedian spots and large ones on epimera ( Figs. 2A–B View FIGURE 2 , 3C View FIGURE 3 ). Antenna, pereopods and pleopods slightly to quite pigmented. Eusphaeric-type conglobation ( Fig. 2B View FIGURE 2 ). Pereon and pleon epimera strongly arched, directed downwards vertically ( Fig. 3A View FIGURE 3 ). Dorsum smooth, without granulations ( Fig. 3A–C View FIGURE 3 ); integument with circular cavities; scale-setae tricorn type with elongated and sharp tip ( Fig. 4A View FIGURE 4 ). Cephalon. Duplocarinate-type, with scutellar ridge more marked than post-scutellar ridge ( Figs 3B View FIGURE 3 , 4B–C View FIGURE 4 ). Frontal shield with concave sides, slightly raised above vertex, separated from it, forming subscutellar pit ( Figs 3B View FIGURE 3 , 4B–C View FIGURE 4 ). Eyes with 18–20 ommatidia ( Figs. 3A–B View FIGURE 3 , 4B–C View FIGURE 4 ). Pereon. Posterior margin of pereon-tergites 1–2 forming clear angles with corresponding epimera; tergite 1 with acute posterior corner; tergites 3–4 with slightly sinuous posterior margin; tergites 5–6 with straight posterior margin; tergite 7 posterior margin slightly angled at sides ( Figs. 2A View FIGURE 2 , 3A View FIGURE 3 ). Pleon. Pleon-tergites with epimera directed backwards; epimera of pleonites 3–4 with acute posterior corners; epimera 5 with more rounded posterior corners ( Figs. 3C View FIGURE 3 , 4D View FIGURE 4 ) Pleotelson. Triangular, about 1.4 times as wide as long, with rounded tip ( Figs. 3C View FIGURE 3 , 4D View FIGURE 4 ).

First Antenna. Three-jointed, with medial article about half as long as other two; distal article bearing 8–10 aesthetascs and small triangular tip ( Fig. 4E View FIGURE 4 ). Second antenna. Reaching posterior margin of first pereon-tergite when extended backwards. Flagellum 2-jointed with proximal article three times shorter than distal ( Fig. 4F View FIGURE 4 ). Distal article with two groups of tiny aesthetascs.

Mouthparts. Mandibles with dichotomized molar penicils; left mandible ( Fig. 4G View FIGURE 4 ) with 2 penicils on hairy lobe and 4 free penicils; right mandible ( Fig. 4H View FIGURE 4 ) with 1+1 penicils. Maxillula: outer branch ( Fig. 4I View FIGURE 4 ) with 4 strong teeth, 5 cleft smaller teeth and one simple tooth; inner branch ( Fig. 4J View FIGURE 4 ) with 2 long penicils and short posterior corner. Maxilla ( Fig. 5A View FIGURE 5 ) with outer lobe twice as wide as inner one; 3+1 setae between lobes. Maxilliped ( Fig. 5B View FIGURE 5 ): first palp article with 2 setae; second palp article with three strong setae and several smaller ones; distal article with short apical setae; endite sub-quadrangular with parallel sides, strong seta on caudal face, two teeth on anterior edge and protruding triangular anterolateral corner.

Pereopods. All pereopods sexually dimorphic, with different number of ventral setae in males than in females; dactyli with inner claw shorter than outer one. Pereopod 1 ( Fig. 5D View FIGURE 5 ) with longitudinal antennal-grooming brush. Male pereopod 7 ( Fig. 5E–F View FIGURE 5 ) specially modified.

Pleopods. Pleopod exopodites 1 and 2 with polyspiracular lungs and notched outer margin of tracheal field, in both males and females ( Figs. 3F–H View FIGURE 3 ; 6A–D View FIGURE 6 ). Exopodites 3–5 subtriangular in males ( Fig. 6E–G View FIGURE 6 ), subquadrangular in females.

Uropods. Endopods inserted proximally on medial margin of protopods; cylindrical with outer margin straight, inner margin slightly widened medially. Exopods plate-like, trapezoidal, slightly wider than long, with rounded posterior corners ( Fig 5C View FIGURE 5 ).

Male

Pereopods 1 ( Figs 3D View FIGURE 3 , 5D View FIGURE 5 ) to 6 with ventral brush of setae on carpus; ventral setae on merus, more abundant on 5th and 6th pereopods. Pereopod 7 ( Figs. 3E View FIGURE 3 , 5E–F View FIGURE 5 ), ischium with enlarged distal half, ventral margin strongly concave with many piliform setae extended to frontal and caudal faces, 4–5 strong setae on dorsal edge; merus with protruded basal heel and several strong setae on ventral margin; carpus with ventral brush of strong setae and keeled dorsal edge. Pleopod 1 ( Figs. 3F–G View FIGURE 3 , 6A View FIGURE 6 ): exopod triangular with short posterior lobe, distally rounded and notched outer margin of tracheal field; endopod three times as long as exopod, straight, not progressively narrowed and weakly curved distally, with some apical spines. Pleopod 2 ( Figs. 3H View FIGURE 3 , 6B View FIGURE 6 ): exopod triangular, with long and straight posterior lobe and notched outer margin of tracheal field; endopod thin and long, surpassing exopod length.

Remarks

Due to its duplocarinate-type cephalic structure and eusphaeric conglobation ability, A. boalense sp. nov. should be included in the ‘ pictum ’ group, according to the definition of Vandel (1962). In the Iberian Peninsula three species belonging to this group have been recorded: A. pictum Brandt, 1833 , A. album Dollfus, 1887 , and A. galiciense Schmölzer, 1955 . Furthermore, in other regions of Western Europe close to the northern Iberian Peninsula (e.g., Ireland or France) an extra species has also been found: Armadillidium pulchellum (Zenker) . A. boalense sp. nov. is externally very similar to A. pictum . Both species show a very similar coloration, which can lead to confusion. However, the new species differs from A. pictum mainly in having the endopodite of the male pleopod 1 almost completely straight, instead of strongly bent from the middle; in the exopod of the pleopod 2, unbent and more distally narrowed instead of with the distal half bent outwards; and in having a greater differentiation of the male pereopod 7, with the ischium with a much larger setose area and a much more pronounced proximal heel than in A. pictum . The cephalic structure of both species is very similar, but in A. boalense the scutellar (frontal) ridge is more marked than the post-scutellar ridge, while it is the other way around in A. pictum . The new species differs from A. album in the exopodites of the male pleopods 1–2; in having triangular scale-setae instead of erect bristles; in the morphology of the male pereopod 7, and in the shape of telson, which is trapezoidal in A. album , instead of triangular. The coloration also differs because A. album is a whitish species with few spots. From A. galiciense differs in the shape of the male pleopods 1–2 and in the strong differentiation of the male pereopod 7. In A. galiciense , the exopod of the male pleopod 7 lacks a posterior lobe and the endopod is even straighter. Moreover, the male pereopod 7 of A. galiciense is not modified. Finally, it differs from A. pulchellum mainly by the endopod of the male pleopod 1; by the exopod of the male pleopod 2, and by the modifications of the male pereopod 7, with very different shape and spinnulation in both species.

Collection site and ecology

The population of Armadillidium boalense sp. nov. was located in Os Chaos (Boal) in the Principality of Asturias (northern Spain) ( Fig. 1A View FIGURE 1 ). The collecting area has an Atlantic macrobioclimate with mesotemperate climate ( Rivas-Martínez et al. 2017). The area of Boal mean annual temperature is 11.2 ºC and 1250 mm mean annual precipitation (data available at https://es.climate-data.org). This species can be categorized as an epigeous species. Specimens were found in a wall of granite stones which also composed the geological substrate of the study area ( Fig. 1B–C View FIGURE 1 ). Woodlice were usually found among the stones of the wall, although some specimens were found directly on the ground. The wall is closer to a mature forest composed mainly by pedunculate oak ( Quercus robur L.) ( Fig. 1B View FIGURE 1 ), which has in its vicinity a replantation of southern blue gum ( Eucalyptus globulus Labill. ). Under the wall stones there were an important organic matter accumulation mainly composed of peduncle oak leaf litter and mosses. The species is locally abundant and share habitat with other arthropods such as the woodlouse Oniscus asellus L. or centipedes of the genus Lithobius L. The area presents a slight anthropization due to the traffic of people and, sometimes, vehicles, and due to the proximity to several urban areas and villages.