Andiperla morenensis Pessacq & Rivera, 2019

Pessacq, Pablo & Rivera-Pomar, Rolando, 2019, A new Andiperla Aubert (Plecoptera, Gripopterygidae) species from the Perito Moreno Glacier, Argentina, Zootaxa 4664 (2), pp. 251-260 : 252-257

Andiperla morenensis Pessacq & Rivera n. sp.

( Figs. 1–4 , 7 )

Type Material. Holotype adult male: ARGENTINA, Santa Cruz Province, National Park “Los Glaciares”, 10– 12.ii.2017, D. Bea, R. P. Kühnlein, P. Pessacq, R. Tintorelli, and R. Rivera Pomar leg ( MLP) . Paratypes: 1 male, 1 female adult, same as holotype. 1 male, 1 female last instar larva, same as holotype, except 20–21.ii.2018, D. Bea, R. P. Kühnlein, R. Nelson, P. Pessacq, and R. Rivera Pomar leg. 2 male adults, same as holotype except 8–10.ii.2019 ( MLP) .

Diagnosis: Medium sized, slender, apterous stoneflies living on glaciers of southern South America. Larvae with large eyes (maximum head width larger than thorax), thin short legs and relatively short antennae and cerci. This species can be distinguished from A. willinki , the only other known species of the genus, by the posterior margin of tergum X extended into a posteriorly directed acute lobe and a well-developed, conical epiproct in adult males.

Description. Male holotype. Measurements: Total length 13.8 mm, head max. width 2.3 mm, antennae 6.5 mm, pronotum max. width 1.8 mm, pronotum max. length 1.6 mm.

Head. Brown, wider than thorax, mostly bare, with short setae on ventral side of scape. Eyes large, protruding laterally, ocelli lacking. Cephalic suture a shallow V. Antennifer membranous, large. Antennae bare, with 30–33 annuli, as long as 3 maximum head lengths; scape about as long as wide, pedicel smaller, slightly wider than first annulus, which is the longest, slightly longer than pedicel. Second annulus the shortest, remaining ones progressively thinner and slightly longer. Labrum trapezoidal, with a few short setae, anterior margin convex, lateral margins slightly divergent anteriorly.

Thorax. Dorsally brown, with a longitudinal medial dark line, surface bare, but with small dots only visible under high magnification that may indicate bases of minute setae. Pro-, meso- and metanotum margins with a few short setae. Pronotum about 1.2 X as wide as long, maximum width 0.8 X head maximum width, margins convex, lateral margins approximately parallel; angles rounded. Mesonotum about as long as wide, maximum width 0.80 X head maximum width, margins slightly convex, lateral margins convergent anteriorly, posterior margin with rounded lateral projections resembling small wing pads. Metanotum slightly longer than wide, maximum width 0.75 X maximum head width, same as mesonotum. Legs light brown, thin, covered by short hair-like setae, tibia apparently bare. Femora darker at apex; tibiae darker at base, with two small tibial spurs; tarsi with a few ventral short spine-like setae; tarsomeres proportions as follows: 1.5:1.5:3.5; tarsal claws acute.

Abdomen. Brown, ventrally covered with small hair-like setae, dorsally with a very few small hair-like setae. Distal margin of terga I–VIII thickened, forming a distal ring visible in dorsal view. Sternum I small, tergum I small, terga and sterna II–VII separated by narrow membranous pleura, segments VIII–X forming a complete ring. Anterior margin of tergum IX concave. Dorsum of segment X with an anterior light brown membranous area ( Fig. 1a ), remainder well sclerotized, dark brown, produced dorso-distally into an acute lobe directed posteriorly ( Figs. 1 a–c), with its tip slightly curved down ( Fig. 1b ). Anterior sclerites not clearly delimited, central, lateral and posterior sclerites indistinguishable, fused. Epiproct ( Figs. 1a, c ) conical, membranous. Paraprocts well developed, about as long as tergum X length, curved upwards, tapering to apex and with pointed tip. Cerci composed of 20–21 segments, each of them progressively thinner and longer, bare.

Male paratypes. Measurements (n=3): Total length 13.85 ± 0.1 mm, head max. width 2.38 ± 0.1 mm, antennae 6.46 ± 0.55 mm, pronotum max. width 1.9 ± 0.13 mm, pronotum max. length 1.57± 0.06 mm.

Same as holotype, except segment X lobe slightly thinner and with more acute apex. In the two specimens collected in 2019, the dorsal side of the epiproct is more heavily sclerotized.

Adult female. Measurements (n=1): Total length 14.3 mm, head max. width 2.5 mm, antennae 6.3 mm, pronotum max. width 2.05 mm, pronotum max. length 1.6 mm.

Same as male holotype except: Head. Mostly bare, with a few short setae on antennifer inner margin and with small dots, only visible under high magnification that may be bases of small setae. Antennae bare, with 30–32 annuli, as long as 2.5 maximum head length. Labrum bare.

Thorax. Pronotum about 1.2 X as wide as long, maximum width 0.8 X head maximum width, margins slightly convex, lateral margins slightly divergent anteriorly. Mesonotum about 1.3 X as wide as long, maximum width 0.85 X head maximum width. Metanotum about 1.2 X as wide as long, maximum width 0.8 X head maximum width.

Abdomen. Segment X produced dorso-distally as an angulated lobe ( Fig. 2 ). Cerci composed of 19–20 segments. Paraproct well developed, longer than tergum X distal margin, with truncated-rounded tip.

Final instar larva. Measurements: Male: total length 14.2 mm, head max. width 2.1 mm, antennae 3.9 mm, pronotum max. width 1.95 mm, pronotum max. length 1.3 mm. Female: total length 17.4 mm, head max. width 2.6 mm, antennae 4.9 mm, pronotum max. width 2 mm, pronotum max. length 1.6 mm

Slender, well sclerotized dark brown larva, with short legs, antennae and cerci. All membranes covered by small branched sensilla ( Fig. 3 ). Head. Dorsally dark brown, mostly bare; ventrally light brown and poorly sclerotized, with many branched sensilla. Eyes big, protruding laterally, no ocelli. Cephalic suture well developed. Antennifer membranous, covered by branched sensilla. Antennae with 35–45 annuli, about as long as 3.2 max. head width, scape much larger than pedicel, which is larger than first annuli; flagellum annuli progressively thinner and slightly longer, with an apical ring of sparse short thick setae. Labrum trapezoidal, anterior margin wider, covered with hairlike setae longer on its anterior third and denser on the sides of anterior margin; anterior margin concave, lateral margins slightly concave. Right mandible ( Fig. 4a, c ) flat, with four teeth, three apical ones united at their base, the two apical ones the sharpest and largest, third one shorter and rounded; the fourth small; mola ( Fig. 4c ) simple, oval, concave, with fine ornamentation, ventro-basal margin with small teeth; dorso-apical surface of mandible covered by hair-like setae, turning to scale-like projections with acute apex towards the base; inner-basal margin with several long setae. Left mandible ( Fig. 4b, d ) flat, with four sharp teeth, two apical larger ones united at their base, and two shorter basal ones; mola ( Fig. 4d ) simple, oval, concave, with one apical triangular tooth, with fine ornamentation, dorsal margin with long acute projections; dorso-apical surface of mandible covered by hair-like setae, turning to scale-like projections with acute apex towards the base ( Fig. 4c ); inner-basal margin of mandible with several long setae. Maxilla ( Figs. 4 e–f) with a five-segmented palp, fifth palpomere the longest, proportions about 0,8:1:1,5:1,2:2; first and second palpomeres with a few setae and small branched sensilla. Galea long and curved inwards, with a few thin hair-like setae, apex square and with many long hair-like setae; lacinia approximately triangular, apex rounded, with no teeth, thin, spoon shaped with dorsal surface concave, with many hair-like setae on its inner margin, longer towards the apex. Labium ( Fig. 4g ) wider than long, with a three-segmented palp covered with several short hair-like setae, denser on distal palpomere, which is the longest, proportions about 1:0,7:0,45; glossa short, apex rounded and with a dense tuft of long hair-like setae, paraglossa long, spreading outwards, apex triangular and with a dense tuft of long hair-like setae on its outer margin.

Thorax. Dorsally dark brown, mostly bare, margins with a row of short sparse spine-like setae; ventrally light brown, mostly membranous, covered by branched sensilla. Pronotum about 1.5 X as wide as long, maximum width about 0.6 X maximum head width, margins convex, angles rounded. Mesonotum about 1.6 X as wide as long, maximum width about 0.7 X maximum head width, anterior margin straight, lateral margins convex, posterior margin concave with rounded lateral projections resembling small wide and shallow wing pads. Metanotum about 1.4 X as wide as long, maximum width about 0.9 X maximum head width, margins as described in mesonotum. Legs: dark brown, short. Femora covered with few short spine-like setae, apex margin with a row of short spine-like setae, apex of flexor margin not sclerotized, forming a membranous V shaped area with branched sensilla, ventro-distal angle rounded; tibiae covered with short spine-like setae, denser than in femora, apex with a row of short spine-like setae, two small tibial spurs; tarsi covered by small spine-like setae, tarsal proportions as follows: 1:1:4; apex of tarsi with a row of short spine-like setae, distal tarsi with a weak ventral row of hair-like setae, four longer spine-like setae on extensor margin apex and one long hair-like seta on middle of extensor margin, tarsal claws acute.

Abdomen. Dark brown. Terga with a row of short spine-like setae on distal margin, membranes covered by branched sensilla. Sternum I small, terga and sterna I–VI separated by membranous pleura, narrower towards the apex, incomplete in segment VI; segments VII–IX forming a complete ring, segment X forms a distally oblique cylinder, produced dorso-distally in a rounded lobe. Cerci composed of 25–32 segments, each of them progressively thinner and longer and with an apical ring of spine-like setae. Anal gills well developed. Paraproct well developed, inner margin concave, outer margin convex, with rounded tip curved upwards.

Etymology. We name this species morenensis , in reference to its type locality, the “Perito Moreno” Glacier.

Distribution. Southern Andes from Perito Moreno Glacier (Andean Region, Patagonian subregion, Santa Cruz Province, Argentina).

Figures

FIGURE 1. Andiperla morenensis n. sp., male holotype. 1a, abdominal segment X, dorsal view. 1b, abdominal segment X, lateral view. 1c, abdominal segment X, posterior-lateral view.

FIGURE 2. Andiperla morenensis n. sp., female. 2a, abdominal segment IX–X, dorsal view. 2b, abdominal segment IX–X, lateral view. 2a, abdominal segment IX–X, ventral view.

FIGURE 3. Andiperla morenensis n. sp., male. 4a–b, detail of branched sensilla (chloride cells) on abdomen membrane, scanning microscope image.

FIGURE 4. Andiperla morenensis n. sp., male. 4a, right mandible, ventral view. 4b, left mandible, ventral view. 4c, right mandible, ventral view and detail of mola, scanning microscope image. 4d, left mandible, ventral view and detail of mola, scanning microscope image. 4e, maxilla, ventral view. 4f, maxilla, detail of palpus, lascinia and galea, ventral view. 4g, labium, ventral view.

FIGURE 7. Andiperla morenensis n. sp. male, habitus.