Iberiarmadillidium, 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 : 1326-1327

IBERIARMADILLIDIUM GEN. NOV.

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 / u r n: l s i d: z o o b a n k. o r g: a c t: 3 2 B C 4 C A 3 - A 6 4 3 - 4C5F-B69D-815CF20C6F34

Type species: Iberiarmadillidium psammophilum sp. nov. by present original designation.

Etymology: From the Latin Iberia, Spain, and the genus Armadillidium , which in turn means ‘small armadillo’.

Diagnosis: Endoantennal, euspheric conglobation. Eluma - type cephalon, with a frontal line continuing the scutellar upper margin and no trace of a postscutellar line. Scutellum triangular, wider 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. Cephalic shield covered by three or four transverse rows of tubercles, irregularly arranged except for the caudal one. Pereonites with two or three transverse rows of large tubercles. Pleonites with one transverse row of tubercles. Pereonite 1 epimera with a small schisma. Shape of distal part of pereonite 4 and 5 epimera broad, with squarish to broadly rounded angles. Epimera of pereonites 2 or 2 and 3 with sinuous, slightly concave outer margin. Surface of pereon, pleon and epimera mostly covered by round, convex, scale-like papillae with irregular margins. Glandular fields in pereon 2 and 3 epimera with one or two pores, longitudinally elongated, elliptical, submedially located in the lateral margin. Pleopod 1 exopod with concave proximal and distal margins. Pleopod 2 exopod clearly longer (~1.5 times) than wide.

Remarks: This new genus can be diagnosed from all other Armadillidiidae genera by a combination of morphological characters. From Alloschizidium Verhoeff, 1919 it differs in having an Eluma - type head, a rounded triangular telson [truncate in all species of Alloschizidium except Alloschizidiumracovitzai (Vandel, 1954)] reduced but well-marked eyes, pigmentation developed, and presence of tubercles in pereon and pleon tergites; from Armadillidium it differs in having an Eluma - type head, presence of a schisma in pereonite 1 epimera (present in a few Armadillidium species in the Armadillidium pruvoti group) and reduced eyes; from Ballodillium it differs in having tubercles in pereon and pleon tergites, reduced eyes, lacking pilose setae covering the body, and absence of a groove along the margin of pereonite 1 epimera. From Cristarmadillidium , the most similar genus morphologically, it differs in having sinuous, slightly concave outer margin of pereonite 2 epimera, pereonite 4 and 5 epimera distally broad, with squarish to broadly rounded angles, tegument covered by round, convex, scale-like papillae, glandular fields in pereon 2 and 3 epimera longitudinally elongated and close to the lateral margin, and pleopod 2 exopod much longer than wide. From Cyphodillidium Verhoeff, 1939 it differs in having a rounded triangular telson, uropod exopodite about two times as broad as long, reduced eyes, and posterior corner of pereonite 1 epimera not produced acutely backwards. From Echinarmadillidium Verhoeff, 1901 it differs in having an Eluma - type head, a rounded triangular telson, reduced but well-marked eyes, absence of a schisma in pereonite 2 epimera, and absence of a groove along the margin of pereonite 1 epimera. From Eleoniscus Racovitza, 1907 it differs in having eyes, presence of a schisma in pereonite 1 epimera, pigmentation developed, presence of tubercles in pereon and pleon tergites, uropod exopodite about two times as broad as long, and lacking pilose setae covering the body. From Eluma it differs in having eyes with several ommatidia instead of the single ommatidium typical of Eluma . From Paraschizidium Verhoeff, 1919 it differs in having a schisma in pereonite 1 epimera, reduced but well-marked eyes, threesegmented antennula, pigmentation developed, and presence of tubercles in pereon and pleon tergites. From Paxodillidium Schmalfuss, 1985 it differs in having a schisma in pereonite 1 epimera, two or three transverse rows of tubercles on each pereon tergite, rectangularshaped uropod exopodite, and a rounded triangular telson. From Platanosphera Strouhal, 1956 it differs in in having a schisma in pereonite 1 epimera, two or three transverse rows of tubercles on each pereon tergite, tegument covered by round, convex, scale-like papillae and male pleopod exopodite 1 with hindlobe. From Schizidium Verhoeff, 1901 it differs in having a rounded triangular telson and presence of tubercles in pereon and pleon tergites. From Trichodillidium Schmalfuss, 1989 it differs in having an Eluma - type head, reduced eyes, pigmentation developed, presence of tubercles in pereon and pleon tergites and lacking pilose setae covering the body. From Troglarmadillidium Verhoeff, 1900 it differs in having a schisma in pereonite 1 epimera, reduced but well-marked eyes, pigmentation developed, uropod exopodite about two times as broad as long, presence of a frontal scutellum in the cephalon, presence of a frontal line and antennal lobes and presence of tubercles in pereon and pleon tergites; from Trogleluma Vandel, 1946 it differs in having a schisma in pereonite 1 epimera, reduced but well-marked eyes, pigmentation developed, uropod exopodite about two times as broad as long and presence of tubercles in pereon and pleon tergites. From Typhlarmadillidium Verhoeff, 1900 it differs in having a schisma in pereonite 1 epimera, reduced but wellmarked eyes, pigmentation developed, uropod exopodite about two times as broad as long, frontal scutellum closed and presence of tubercles in pereon and pleon tergites.

All three Iberiarmadillidium species share a similar general habitus ( Fig. 5A–C ). However, they also present high genetic divergences, particularly for the mitochondrial DNA gene Cox1, with mean interspecific uncorrected p -distances of 20–21%. In the case of nuclear markers, with much slower substitution rates than Cox1, mean uncorrected p -distances among species ranged from 0.5 to 0.7% in the analysed fragment of the 18S, from 0.20 to 0.35% in 28S and from 0.7 to 2.3% in H3.

Figures

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).