Iberiarmadillidium pinicola, Recuero & Rodríguez-Flores & García-París, 2022

Recuero, Ernesto, Rodríguez-Flores, Paula C. & García-París, Mario, 2022, Homoplasy and morphological stasis revealed through multilocus phylogeny of new myrmecophilous species in Armadillidiidae (Isopoda: Oniscidea), Zoological Journal of the Linnean Society 194 (4), pp. 1312-1340 : 1327-1329

IBERIARMADILLIDIUM PINICOLA SP. NOV.

( FIGS 1A , 5B , 6B , 7B , 8B , 10A–K )

Z o o b a n k r e g i s t r a t i o n: h t t p: / / z o o b a n k. o r g / urn:lsid:zoobank.org:act:E9B5A8E2-4DD1-4E7B-A3BE-F0F1814DDAAA

Material examined: Holotype: male ( MNCN 20.04 /14368), Spain, Castilla y León, Ávila Province, ~ 8 km noth-east of Hoyo de Pinares , 40°31′40″N, 4°20′04″W, 1 April 2013.

Paratypes: five males and five females ( MNCN 20.04 /14369- MNCN 20.04 /14378), same locality and date as holotype. – One female ( MNCN 20.04 /14379), Spain, Comunidad de Madrid, Valdemaqueda , 40°29′12″N, 4°17′52″W, 4 May 2016 .

Etymology: From the Latin pinus, pine, and colere, to inhabit, in reference to the extensive forests of Pinus pinea L. where the species has been found.

Diagnosis: A species of Iberiarmadillidium characterized by the presence of elongated, elevated tubercles, keel-like and with squarish profile, particularly those in the posterior rows. Lateralmost tubercles of pereonite 7 elongated, with the frontal one longer than the caudal one. Pereonite 2 epimera with sinuous outer margin, pereonite 3 epimera with straight outer margin. Colour uniform, epimera barely lighter than dorsal parts. Outer lobe of pleopod 1 endopod with almost straight margin. Pleopod 2 exopod with deeply concave outer/distal margin; pleopod 2 endopod narrow, particularly in its distal third. Pleopod 4 exopod with concave distal margin.

Description: Maximum length: ♂ 6.2 mm, ♀ 7 mm. Maximum width: ♂ 3mm, ♀ 3.5 mm.Colour in life brownish, barely lighter in tubercles and epimera; antennae and pereopods whitish ( Fig.1A ). Colour of preserved specimens, after ≤ 9 years in ethanol, fades to light brown or off-white. Body habitus ( Figs 1A , 5B ) strongly convex, able to roll up into a perfect ball, with pereon and pleon covered by rows of usually elongated tubercles; epimera vertical but with lateral margin slightly directed outwards.

Tegument with whole surface of pereon, pleon and epimera, except tips of tubercles, covered by round, convex, scale-like papillae with irregular margins, observed in SEM images ( Figs 5B , 6B , 7B ); with sparse but evenly distributed small scale-setae with broad base and short tip, present also on tubercles; scalesetae stouter, not so clearly broad basally in parts of the head, such as scutellum, frontal line, antennae and clypeum; in pereopods, scale-setae large to large, acutely triangular, resembling small spines; glandular fields with two pores, transversely elliptical, anteriorly located in epimera 1, located submedially and clearly separated from lateral margin in other epimera, but not observed in every epimera.

Cephalon ( Fig. 8B ) of Eluma type, with a frontal line continuing the scutellum upper margin and no trace of a postscutellar line. Scutellum triangular, broader than high, slightly concave in the middle, clearly separated from vertex but not protruding above it. Antennary lobes well developed, obliquely directed frontwards. Eyes small, with four to six pigmented ommatidia partly covered by tegument. Cephalic shield covered by four rows of tubercles, irregularly arranged except the caudal one, formed by ten tubercles usually not much larger than the rest. Tubercles behind the eyes not larger than the others

Pereonites ( Fig. 5B ) with elongated and elevated, keel-like tubercles, squarish in lateral profile, particularly in caudal rows. Pereonite 1 with three or four rows of tubercles, the caudal one more regularly arranged, formed by 14 tubercles; posterior margin straight, concave in the epimera; epimera 1 with four to six irregularly arranged tubercles, smaller than those in the pereonite; caudal angle with a small schisma ( Fig. 6B ), with inner lobe shorter than outer one, not forming a sulcus along the lateral margin; ventrally with small rounded ventral teeth. Pereonite 2 with three rows of elongated tubercles, the middle one irregular and formed by smaller, rounder tubercles, the caudal one with 14 tubercles; epimera 2 with three or four small- to medium-sized tubercles and sinuous outer margin; ventrally with the anterior half thickened and a small rounded tooth; lateral profile squarish, with outer margin slightly sinuous. Pereonite 3 with two rows of elongated tubercles, with some isolated, small, rounded tubercles among them, the caudal one with 14 tubercles; epimera 3 with one small but marked tubercle and straight outer margin; ventrally with the anterior third thickened and a smallventral tooth; lateral profile squarish. Pereonite 4 with two rows of tubercles, frontal one not clearly elongated, caudal one with 15 elongated tubercles; epimera 4 with a barely marked tubercle; ventrally with no thickening; lateral profile squarish. Pereonite 5 with two rows of tubercles, with some small isolated tubercles among them, frontal one not clearly elongated, caudal one with 14 elongated tubercles; epimera 5 with a barely marked tubercle; ventrally with no thickening; lateral profile squarish. Pereonite 6 with two rows of elongated tubercles, with some small isolated tubercles among them, the caudal one with 13 or 14 tubercles, usually longer than the frontal ones; epimera 6 with two barely marked tubercles; ventrally with the anterior half thickened; lateral profile squarish. Pereonite 7 with two rows of tubercles, the caudal one with 11 or 12 tubercles, usually longer than the frontal ones; lateralmost frontal tubercle elongated, longer than the posterior; epimera 7 with one or two barely marked small tubercles; ventrally with the anterior two-thirds thickened; lateral profile squarish.

Pleonites with one row of tubercles each, formed by eight round, medium-sized tubercles in pleonite 1, eight to ten tubercles in pleonites 2–4, and pleonite 5 with six tubercles, the central, paramedian pair clearly larger than the others ( Fig. 7B ). Neopleura 3 and 4 with one barely marked tubercle; neopleura 5 with no tubercles apparent. Telson ( Fig. 7B ) triangular, with broadly rounded apex; surface almost flat, with two paramedian medium-sized tubercles.

Antennula three-segmented: first article broadest, second article shortest, and third article longest and with subapical aesthetascs. Antenna ( Fig. 10C ) densely covered with small but robust, triangular scale-setae, thinner and longer in the flagellum; fifth article slightly longer than flagellum and bearing distally a long, spiniform seta; second flagellar article 2.5–2.6 times as long as first, bearing two rows of aesthetascs. Pleopod 1 and 2 exopods with covered lungs. Uropod ( Fig. 10D ) covered with triangular scale-setae, with protopod about as long as endopod and twice as long as exopod; exopod about two times as broad as long.

Male: Pereopod 1 ( Fig. 10A ) merus and carpus armed with two lines of long, strong, spiniform setae along sternal margin, longer in the distal end; sternal margin of propodus with long spiniform setae in distal third, proximally with shorter spiniform setae; isolated long, strong, spiniform setae present also in basis, ischium and tergal margin of merus. Pereopod 7 ( Fig. 10B ) with no distinct sexual modifications, ischium with straight sternal margin; densely covered with long, strong, spiniform setae along sternal margin of merus and carpus, less densely in propodus, and isolated in ischium and tergal margin of merus. Pleopod 1 exopod ( Fig. 10E ) with internal half rounded, about two times as long as external half, with concave proximal and distal margins, bearing a few setae in distal margin. Endopod ( Fig. 10F ) 2.2 times as long as exopod; outer lobe with clearly convex margin; distal portion moderately acute, with no differentiated structures. Pleopod 2 exopod ( Fig. 10G ) subtriangular, with acute distal end and deeply concave outer/distal margin bearing a line of long setae, a bit stouter at the level of the lung, and slightly concave proximal margin; endopod ( Fig. 10H ) ~1.4 times as long as exopod; narrow, particularly in its distal third. Pleopod 3 exopod ( Fig. 10I ) with concave outer/distal margin; pleopod 4 exopod ( Fig. 10J ) with slightly concave outer/distal margin and a strong concavity in proximal margin; outer/distal margin of pleopod 5 exopod straight ( Fig. 10K ).

Remarks: The two known populations are close, s e p a r a t e d b y o n l y ~ 5 k m, a n d t h e h a b i t a t i s characterized by sandy, siliceous soils and vegetation dominated by forests of Pinus pinea . They have been found during the spring months under stones harbouring ant nests. Regrettably, ants are not available for identification.

Figures

Figure 1. Map showing the sampling localities of Iberiarmadillidium pinicola (black stars), I. psammophilum (purple stars), I. sakura (white star), Cristarmadillidium breuili (black circle), Cristarmadillidium muricatum (red circles) and C. myrmecophilum (yellow circles). Habitus in vivo: A, I. pinicola from Valdemaqueda, Madrid; B, I. psammophilum from El Pardo, Madrid; C, C. myrmecophilum from Casas de Don Antonio, Cáceres; D, C. muricatum from Punta de Benimaquia Cave, Alicante; and E, C. breuili from Bolumini Cave, Alicante.

Figure 5. Scanning electron photomicrographs showing the general habitus of Iberiarmadillidium psammophilum (A), Iberiarmadillidium pinicola (B), Iberiarmadillidium sakura (C), Cristarmadillidium myrmecophilum (D) and Cristarmadillidium muricatum (E).

Figure 6. Scanning electron photomicrographs showing details of pereonite 1 and 2 epimera of Iberiarmadillidium psammophilum (A), Iberiarmadillidium pinicola (B), Iberiarmadillidium sakura (C), Cristarmadillidium myrmecophilum (D) and Cristarmadillidium muricatum (E) (only epimera 1 is shown).

Figure 7. Scanning electron photomicrographs showing details of the telson of Iberiarmadillidium psammophilum (A), Iberiarmadillidium pinicola (B), Iberiarmadillidium sakura (C), Cristarmadillidium myrmecophilum (D) and Cristarmadillidium breuili (E).

Figure 8. Scanning electron photomicrographs showing details of the head of Iberiarmadillidium psammophilum (A), Iberiarmadillidium pinicola (B), Iberiarmadillidium sakura (C) and Cristarmadillidium myrmecophilum (D).

Figure 10. Iberiarmadillidium pinicola from ~8 km north-east of Hoyo de Pinares, male paratype: A, pereopod 1; B, pereopod 7; C, antenna; D, uropod; E, pleopod 1 exopod; F, pleopod 1 endopod; G, pleopod 2 exopod; H, pleopod 2 endopod; I, pleopod 3 exopod; J, pleopod 4 exopod; and K, pleopod 5 exopod.