Iberiarmadillidium sakura, 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 : 1332-1334

IBERIARMADILLIDIUM SAKURA SP. NOV.

( FIGS 5C , 6C , 7C , 8C , 12A–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 / u r n: l s i d: z o o b a n k. o r g: a c t: 3 D 2 3 D F 7 F - 8 E 3 2 - 43AE-9CA9-9B607DD83938

Material examined: Holotype: male ( MNCN 20.04 /14363), Spain, Extremadura, Cáceres Province, Jerte , 40°12′48″N, 5°46′41″W, 4 April 2011.

Paratypes: two males and two females ( MNCN 20.04 /14364- MNCN 20.04 /14367), same locality and date as holotype .

Etymology: From Japanese さくら or サクĵ (sakura), cherry blossoms, used here as a noun in apposition. Cherries are one of the most popular products from Valle del Jerte, where many cherry orchards are found. The flowering of cherry trees in springtime has become a famous and celebrated event.

Diagnosis: A species of Iberiarmadillidium characterized by rounded tubercles in pereonites, generally not elongated as in I. pinicola or I. psammophilum . Lateralmost tubercles of pereonite 7 elongated, the frontal one longer than the caudal one. Tubercles in pleonite 5 equal to subequal in size. Pereonite 2 epimera with sinuous outer margin, pereonite 3 epimera with straight outer margin. Colour of epimera 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 half. Pleopod 4 exopod with concave distal margin.

Description: Maximum length: ♂ ~ 4.2 mm, ♀ 4.3 mm. Maximum width: ♂ ~ 2.1 mm, ♀ 2 mm. Colour of preserved specimens, after almost 10 years in ethanol, off-white dorsally, almost white in the epimera and ventrally. Colour in life not recorded. Body habitus ( Fig. 5C ) strongly convex, able to roll up into a perfect ball, with pereon and pleon covered by rows of rounded tubercles; epimera vertical but with lateral margin directed slightly outwards.

Tegument with whole surface of pereon, pleon and epimera covered by round, convex, scale-like papillae with irregular margins, visible in SEM images ( Figs 5C , 6C , 7C ), absent in tips of tubercles and some small areas between them; with sparse but evenly distributed small scale-setae with broad base and short tip, present also on tubercles; scale-setae stouter in parts of the head, such as scutellum, frontal line and clypeum; in antennae, pereopods and uropods scale-setae stout, acutely triangular, longer and thinner in antennal flagellum; glandular fields with one or two pores, longitudinally elongated, elliptical, anteriorly located in epimera 1, submedially located in the lateral margin of other epimera, but not observed in every epimera.

Cephalon ( Fig. 8C ) of Eluma type; 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; cephalic shield covered by three or four rows of tubercles, irregularly arranged except the caudal one, formed by ten tubercles usually slightly larger than the rest, with tubercles behind the eyes larger than the others.

Pereonites ( Fig. 5C ) with transverse rows of rounded tubercles. Pereonite 1 with three or four rows of tubercles, the caudal one more regularly arranged, formed by 13 or 14 tubercles; posterior margin straight, concave in the sides; epimera 1 with four to six irregularly arrange tubercles of different sizes; caudal angle with a small schisma, with poorly differentiated inner lobe shorter than outer one, not forming a sulcus along the lateral margin. Pereonite 2 with three rows of tubercles, the middle one irregular and formed by smaller tubercles, the caudal one with 13 or 14 tubercles; epimera 2 with two or three poorly defined tubercles and sinuous outer margin. Pereonite 3 with two rows of tubercles, with some small isolated tubercles among them, the caudal one with 13–15 tubercles; epimera 3 with one or two barely marked tubercles and straight outer margin. Pereonite 4 with two rows of tubercles, sometimes with some small isolated tubercles among them, the caudal one with 13 or 14 tubercles; epimera 4 with a barely marked tubercle, lateral profile squarish to broadly rounded. Pereonite 5 with two rows of tubercles, with some small isolated tubercles among them, the caudal one with 14 tubercles; lateralmost tubercles usually elongated, subequal; epimera 5 with or without a barely marked tubercle, lateral profile squarish. Pereonite 6 with two rows of tubercles, often with some small isolated tubercles among them, the caudal one with 11–13 tubercles; lateralmost tubercles usually elongated, subequal; epimera 6 with one or two barely marked tubercles, lateral profile squarish. Pereonite 7 with two rows of tubercles, with or without some small isolated tubercles among them, the caudal one with 11 or 12 tubercles, those in the middle smaller than lateral ones; lateralmost tubercles elongated, the anterior ones longer than the posterior; epimera 7 with one or two barely marked tubercles, lateral profile squarish. Pleonites 1 and 2 with one row of eight round, medium-sized tubercles. Pleonite 3 with one row of ten tubercles. Pleonite 4 with one row of eight to 11 tubercles. Pleonite 5 with one row of six tubercles, subequal ( Fig. 7C ). Neopleura 3 and 4 with one barely marked tubercle; neopleura 5 with no tubercles. Telson ( Fig. 7C ) 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 with subapical aesthetascs. Antenna ( Fig. 12C ) with fifth article of peduncle slightly longer than flagellum; second flagellar article 2.3–2.4 times as long as first, bearing up to five rows of one to three aesthetascs.

Male: Pereopod 1 ( Fig. 12A ) merus and carpus armed with irregular lines of long, strong, spiniform setae along sternal margin, three to five long spiniform setae scattered in distal half of sternal margin of propodus. Pereopod 7 ( Fig. 12B ) with no distinct sexual modifications; ischium with straight to slightly concave sternal margin. Sternal margin of carpus and propodus armed with long, strong, spiniform setae, present in merus only in its distal end. Pleopod 1 exopod ( Fig. 12E ) with internal half ~2.2 times as long as external half, with concave proximal and distal margins; distal and proximal ends of inner half broadly rounded, bearing a single seta in distal margin; endopod ( Fig. 12F ) 2.3 times as long as exopod; outer lobe with almost straight margin; distal portion ending in a narrow apex, with no differentiated structures. Pleopod 2 exopod ( Fig. 12G ) long, with deeply concave outer/ distal margin bearing long setae and slightly convex proximal margin; endopod ( Fig. 12H ) ~1.3 times as long as exopod; narrow, particularly in its distal half. Pleopod 3 and 4 exopods ( Fig. 12I ) with concave distal margins, straight in 5 ( Fig. 12J, K ), all of them bearing setae.

Remarks: The only known population was located under a stone, half-buried by soil and leaf litter and hosting an ant colony, in an open forest of Quercus pyrenaica Willd. Regrettably , no ants were collected; hence, their identity is unknown.

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).

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 12. Iberiarmadillidium sakura from Jerte, 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.