Ilyobius erebus, Mendes & Nascimento & Fusari & Santos & Hamada, 2022
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publication ID |
https://doi.org/ 10.11646/zootaxa.5165.3.2 |
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publication LSID |
lsid:zoobank.org:pub:99B81CA6-28B2-4678-84BF-53B6F891B388 |
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DOI |
https://doi.org/10.5281/zenodo.6838314 |
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https://treatment.plazi.org/id/3F611B55-FFAE-1777-E1BE-FBFFFAEEFCA0 |
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Plazi |
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Ilyobius erebus |
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sp. nov. |
Ilyobius erebus sp. nov. Mendes, Nascimento, Fusari & Hamada
( Figs 2–10 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 View FIGURE 8 View FIGURE 9 View FIGURE 10 )
Specimens examined. Holotype: male (pinned), with associated pupal and last instar exuviae in glycerin. Brazil, Minas Gerais State, Poços de Caldas, Morro do Ferro (21°53’33.6’’S; 46°33’04.2’’W); 16.VI.2021; N. Hamada, L.M. Fusari, J.O. da Silva, M. R. Santos, cols. ( INPA). GoogleMaps
Paratypes. Same data as holotype: two males: one pinned ( INPA), one fixed in 80% alcohol ( MZUSP), with pupae and exuviae of the last-instar larvae in glycerin; three females: one pinned ( INPA), two fixed in alcohol 80% (one at INPA, one at MZUSP), with pupae and exuviae of the last instar larvae in glycerin; one last-instar larvae ( INPA), fixed in 80% alcohol. GoogleMaps
Diagnosis. Ilyobius erebus sp. nov. is distinguished from all other species in the genus by the following characters. Head and pronotum are almost completely blackish, covered with golden setae ( Fig. 2A–D View FIGURE 2 ). Male sternite 9 is trifurcate, with medial projection longer than lateral ones, in caudal view ( Fig. 4C, D View FIGURE 4 ). Gonocoxite 9 is robust and subtriangular in lateral view. Ectoproct is rounded in lateral view, with ventral margin fused to gonocoxite 11 ( Fig. 4A, B View FIGURE 4 ). Gonocoxite 11 is L-shaped in lateral view ( Fig. 4A, B View FIGURE 4 ), and divided into two sclerites medially connected in caudal view ( Fig. 4C, D View FIGURE 4 ). Gonostylus 11 is pointed and projected upwards in lateral view ( Fig. 4A, B View FIGURE 4 ). Female sternite 7 subtriangular in ventral view ( Fig. 7C, D View FIGURE 7 ), with thumb-shaped projection on distal margin in lateral view ( Fig. 7A, B View FIGURE 7 ). Gonocoxite 8 is reduced, located beneath sternite 7 ( Fig. 7E View FIGURE 7 ). Gonapophysis 8 is subrectangular in shape, with anterior margin concave, posterior margin convex, and anterolateral corners falcate in ventral view ( Fig. 7C, D View FIGURE 7 ). Mature larva head is orange-brown, with darker areas on anterior region ( Fig. 8C View FIGURE 8 ).
Description. Male. Body length: mean = 7.17 mm (Standard deviation (SD) ± 0.391, n = 3); Forewing length: mean = 9.18 mm (SD ± 0.839, n = 3); width: mean = 2.54 mm (SD ± 0.361, n = 3); hindwing, length: mean = 8.25 mm (SD ± 1.06, n = 3); width: 2.55–3.10 mm (n = 2).
Head ( Fig. 2C, D View FIGURE 2 ). Width (at the widest point): mean = 1.64 mm (SD± 0.086, n = 3); length: mean = 1.17 mm (SD ± 0.081, n = 3); region between the posterior margin of the eyes: mean = 1.55 mm (SD ± 0.065, n = 3).
General color blackish, except region of gena, surrounded by dark orange-brown area in lateral view ( Fig. 2D View FIGURE 2 ); densely covered with golden setae. Scape, pedicel and flagellum blackish, with 30 flagellomeres, densely covered with black setae. Frons with a slight depression between the antennae ( Fig. 2C View FIGURE 2 ). Posterior region with numerous muscle scars ( Fig. 2C View FIGURE 2 ). Clypeus and labrum dark brown, densely covered with golden setae; clypeus with median concavity; maxillary and labial palpi dark brown, densely covered with golden and blackish setae ( Fig. 2D View FIGURE 2 ).
Thorax ( Fig. 2A View FIGURE 2 ). Pronotum blackish, rectangular; width: mean = 1.54 mm (SD ± 0.097, n = 3); length: mean = 0.75 mm (SD ± 0.063, n = 3), densely covered with golden setae. Meso- and metanotum blackish, subrectangular and densely covered with short, golden setae.
Legs. Dark brown, densely covered with golden setae; fore femur shorter than mid- and hind femur and slightly expanded. Tibial spurs short, yellow. Basitarsi of fore- and midleg short, slightly smaller than second and third tarsomeres together; longer on hind leg, slightly larger than second and third tarsomeres together. Pretarsal claws yellow.
Wings ( Fig. 3A, B View FIGURE 3 ). Membrane translucent dark brown in alcohol and iridescent blackish in vivo, densely covered with golden setae. Veins light brown, pterostigma absent. Forewing: costal area slightly expanded on proximal 1/3 of the wing length, with nine crossveins; radial area with three crossveins; RP with two branches; M bifurcated near mid-length of wing; MA unforked; MP bifurcated near posterior wing margin; mediocubital area with three crossveins; CuA bifurcated near posterior margin; CuP not bifurcated. Intracubital area with a single crossvein. Area between A1 and A2 with a single crossvein; A2 forked before R fork. Area between A2 and A3 with a single crossvein. Hindwing: similar to forewing; costal area undilated, with nine crossveins; radial area with four crossveins; mediocubital area with a single crossvein; MP not bifurcated; anal area expanded ( Fig. 3B View FIGURE 3 ).
Abdomen. Blackish, densely covered with golden setae.
Genitalia ( Figs 4A–D View FIGURE 4 ; 5A–D View FIGURE 5 ; 6A, B View FIGURE 6 ). Tergite 9 sclerotized, densely setose; subtriangular with rounded margin in lateral view ( Fig. 4A, B View FIGURE 4 ); in dorsal view, sub-rectangular; basal margin concave, distal margin convex ( Fig. 5A, B View FIGURE 5 ). Sternite 9 trifurcate in caudal view, sparsely setose, central projection longer than lateral ones ( Fig. 4C, D View FIGURE 4 ); in lateral view, medial projection wider medially ( Fig. 4A, B View FIGURE 4 ); in ventral view, only medial projection is visible, the lateral ones are not visible ( Fig. 5C, D View FIGURE 5 ). Endophalic sac membranous, eversible, with several fringed thorny setae ( Fig. 6A, B View FIGURE 6 ). Gonocoxite 9 robust, setose; in lateral view, subtriangular with rounded apex, slightly concave in dorsal region, near the rounded apex ( Fig. 4A, B View FIGURE 4 ). Anal tubercle membranous. Ectoprocts paired, in lateral view, rounded; dorsal margins convex, ventral margins straight, posteriorly directed, with proximal margins fused to gonocoxite 11 ( Fig. 4A, B View FIGURE 4 ); in dorsal view, subtriangular, internal margins concave ( Fig. 5A, B View FIGURE 5 ). Gonocoxite 11 L-shaped in lateral view, distal region pointed at apex and projected upwards, representing gonostylus 11 ( Fig. 4A, B View FIGURE 4 ); gonocoxite 11 divided into two sclerites that are medially directed and connected by a membranous region in caudal view, setose ( Fig. 4C, D View FIGURE 4 ); each sclerite with internal margin sinuous.
Female. Body length: mean = 10.51 mm (SD ± 0.375, n = 3); forewing length: mean = 10.76 mm (SD ± 0.189, n = 3); width: mean = 3.19 mm (SD ± 0.249, n = 3). Hindwing length: mean = 9.25 mm (SD ± 0.573, n = 3); width: mean = 3.53 mm (SD ± 0.166, n = 3).
General coloration and external morphology similar to male.
Head. Width (widest region): mean = 2.10 mm (SD ± 0.034, n = 3); length: mean = 1.51 mm (SD ± 0.134, n = 3); region between the posterior margin of the eyes: mean= 1.98 mm (SD ± 0.038, n = 3); scape, pedicel and flagellum blackish with 32 flagellomeres.
Thorax. Pronotum: width: mean = 1.98 mm (SD ± 0.046, n = 3); length: mean = 0.99 mm (SD ± 0.042, n = 3). Forewing: costal area with nine crossveins; area between M and CuA with two crossveins. Hindwing: similar to forewing; costal area with eight crossveins; MP not bifurcated.
Genitalia ( Fig. 7A–E View FIGURE 7 ). Sternite 7 with thumb-shaped, posteriorly projected median projection in lateral view ( Fig. 7A, B View FIGURE 7 ); in ventral view, subtriangular with posterior margin rounded, projected medially ( Fig. 7C, D View FIGURE 7 ). Tergite 9 subtrapezoidal, in lateral view, ventral region broadly valvate; joined to upper region by junction line ( Fig. 7A, B View FIGURE 7 ). Gonocoxite 8 reduced, represented by a small, setose sclerite in ventral view ( Fig. 7E View FIGURE 7 ), located beneath sternite 7 ( Fig. 7C, D View FIGURE 7 ). Gonapophysis 8 as a single straight sclerotized plate; in lateral view, subrectangular with falcate dorsal apex ( Fig. 7A, B View FIGURE 7 ); in ventral view, subrectangular in shape, with anterior margin slightly concave and posterior margin convex, with lateral regions falcate ( Fig. 7C, D View FIGURE 7 ). Gonocoxite 9 subretangular in lateral view, setose, posteriorly with a small gonostylus 9 at apex ( Fig. 7A, B View FIGURE 7 ). Ectoproct setose, in lateral view, short, ovoid ( Fig. 7A, B View FIGURE 7 ).
Mature larvae ( Fig. 8A–D View FIGURE 8 ). Length = 10.24 mm (except caudal filament); maximum width = 2.32 mm (n =1).
Head ( Fig. 8B, D View FIGURE 8 ). Length, from the clypeal margin to distal region of the head capsule = 2.49 mm; maximum width = 2.36 mm; subquadrate. Orange-brown in color, with darker areas on anterior region ( Fig. 8C View FIGURE 8 ); strongly sclerotized; muscle scars on posterior half ( Fig. 8C View FIGURE 8 ); several thin sparse setae distributed on head capsule. Clypeus wide and narrow, length = 0.24 mm; width = 1.72 mm. Antenna ( Fig. 9D View FIGURE 9 ) 4-articulated; first antennomere longer than wide, wider than the others; second antennomere longer than others, ca. 2.5X longer than antennomere 1; antennomere 3 slender, ca. 1.5X longer than antennomere 1; antennomere 4 slender and shorter than antennomere 3, apically with short, setiform sensilla. Labrum ( Fig. 9A View FIGURE 9 ) strongly sclerotized, subtriangular, ca. 5X wider at base than at apex; basally slightly wider than long; lateral margins concave; with thin setae sparsely distributed in dorsal view; in ventral view, with two pointed apophyses at tip. Mandible ( Fig. 9C View FIGURE 9 ) symmetrical, slender and long, sharply pointed with minute basal tooth (difficult to see in specimens with worn mandibles), with two preapical teeth and a sharp terminal tooth, slightly serrated at base; outer margin convex, with basal, thin, long seta, and short slender seta near midlength. Maxilla ( Fig. 9B View FIGURE 9 ), in ventral view, with cardo and stipes subtriangular; cardo ca. 1.5X longer than stipes. Lacinia hook-like, well developed. Galea cone-shaped. Palpifer subrectangular. Palpus: first palpomere wider than long, shorter than others; second palpomere longer than others, twice the length of the third; fourth palpomere cone-shaped. Labium ( Fig. 9B View FIGURE 9 ) with submentum hexagonal in ventral view, ca. 1.1X longer than cardo; mentum subrectangular, slightly longer than wide, ca. 1.8X shorter than submentum, with lightly sclerotized areas; prementum wider than long, ca. 1.2X narrower than mentum; with well-developed membranous ligula.
Thorax ( Figs 8A View FIGURE 8 , 10A–C View FIGURE 10 ). Tergites orange, with diffuse blackish marks, especially on meso- and metanotum ( Fig. 8A View FIGURE 8 ). Pronotum: length = 1.61 mm; maximum width = 2.39 mm; subrectangular, anterior margin slightly rounded, posterior margin straight. Legs ( Fig. 10A–F View FIGURE 10 ): yellowish. Coxa of all legs slightly wider than long, with few setae sparsely distributed ( Fig. 10A–F View FIGURE 10 ). Profemur ca. 3.5X longer than wide; internal margin with long, thick setae; internal surface with two rows of long setae near external margin ( Fig. 10A View FIGURE 10 ); external surface with long, thick setae near external margin and with a row of shorter setae on the submedial region ( Fig. 10B View FIGURE 10 ); mesofemur ca. 3X longer than wide; internal margin with long, thick setae; internal and external surface with a row of long setae near external margin; internal surface with a row of short setae near internal margin ( Fig. 10C View FIGURE 10 ); external surface with a row of short setae on submedial region ( Fig. 10D View FIGURE 10 ); hindfemur ca. 3.5X longer than wide; internal margin with long, thick setae; internal and external surface with a row of long, thin setae near external margin ( Fig. 10E, F View FIGURE 10 ); external surface with a row of shorter setae on submedial region and with a row of pectinate sensillae above submedial row of setae ( Fig. 10E View FIGURE 10 ); internal surface with a row of short setae near internal margin with a row of pectinate sensillae between the internal margin and the row of setae on the submedial region ( Fig. 10F View FIGURE 10 ). Protibia ca. 2.6X longer than wide; mesotibia ca. 2.9X longer than wide; foretibia subequal in size to mesotibia. Tibia of all legs with few, long, thick setae on internal and external margins; with thin, long setae on external margin ( Fig. 10A–F View FIGURE 10 ); internal margin with a long, thick seta; external surface of pro- and mesothoracic legs with a row of short, thick setae submedially ( Fig. 10B, D View FIGURE 10 ); external and internal surface of metathoracic leg with pectinate sensillae below the submedial row of setae ( Fig. 10E, F View FIGURE 10 ). Protarsus ca. 3.5X longer than wide; mesotarsus ca. 3.9X longer than wide; metatarsus ca. 3X longer than wide; internal and external margin of prothoracic and mesothoracic leg with thick setae; external margin with thin setae; external surface with longitudinal row of thick setae dorsally and ventrally ( Fig. 10B, D View FIGURE 10 ); external and internal surface of metathoracic leg, with a row of short, thick setae submedially; with pectinate sensillae below the submedial row of setae ( Fig. 10E, F View FIGURE 10 ). Tarsal claws with approximately the same width along the entire length.
Abdomen ( Fig. 8A View FIGURE 8 ). Poorly sclerotized; light brown; abdominal gills whitish translucent.
Etymology. The specific epithet is derived from Erebus, Latin for darkness, an allusion to the coloration of this new species, the first in the genus that is almost completely dark. The name is a genitive in the fourth declension.
Distribution. Poços de Caldas municipality, Morro do Ferro, Minas Gerais State, Brazil ( Fig. 1A, B View FIGURE 1 ).
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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