Dyscolus aequinoctialis Chaudoir, 1850

Dyscolus aequinoctialis Chaudoir, 1850 View in CoL , bona species

( Fig. 1-3)

Dyscolus (Ophryodactylus) aequinoctialis Chaudoir, 1850: 382 View in CoL . Colpodes aequinoctialis View in CoL : Chaudoir, 1859: 339-340; Chaudoir, 1878: 339. Platynus aequinoctialis View in CoL : Whitehead, 1973: 188 ( lectotype designation). Dyscolus aequinoctialis View in CoL : Moret, 1990: 198.

Dyscolus subviolaceus ( Chaudoir, 1842) View in CoL : Perrault, 1990: 452 (synonymy). Dyscolus subviolaceus View in CoL : Arenas-Clavijo et al., 2021: 40.

Lectotype ♂, “Ex Musaeo Chaudoir”, without locality label, MNHN ( Whitehead 1973: 188).According to the description, the type locality is in Colombia (“plaines de la Colombie ”, Chaudoir, 1850: 383).

Dyscolus aequinoctialis View in CoL is a conspicuous member of the riparian communities of the tropical montane forest in northern Andes: fully winged, 12-14.5 mm long, with metallic blue or bluish elytra ( Fig. 1a). It was synonymized by Perrault (1990: 452) with Dyscolus subviolaceus ( Chaudoir, 1842) View in CoL , a species described from Brazil ( Chaudoir 1842: 834) and more precisely from Nova Friburgo and Cantagalo in the province of Rio de Janeiro ( Chaudoir 1859: 340) ( Fig. 1b). Apart from the type series, we have studied material of D. subviolaceus View in CoL from São Leopoldo ( Rio Grande do Sul, P. Buck leg., ex coll. Jacques Nègre, CPM). D. subviolaceus View in CoL thus appears to belong to

c d e a, c. D. aequinoctialis Chaudoir, 1850 View in CoL , ♂, Otonga , Ecuador.

b, d. D subviolaceus ( Chaudoir, 1842) , ♂, São Leopoldo , Brazil . e. D mendozensis ( Roig-Juñent, 2003) , ♀, Jujuy, Argentina .

a. D. aequinoctialis Chaudoir, 1850 , Otonga, Ecuador.

b. D subviolaceus ( Chaudoir, 1842) , São Leopoldo, Brazil.

c. D mendozensis ( Roig-Juñent, 2003) , Jujuy, Argentina.

b, d & f. D. aequinoctialis Chaudoir, 1850 , Otonga, Ecuador.

the fauna of the Mata Atlântica, quite distant from the tropical northern Andes. The only argument on which Perrault based this synonymy was the variability of the form of the pronotum and of the colour of the body, which supposedly overlapped between the two taxa. However, this statement was not based on precise measurements, and other characters, especially those of the male genitalia, were not taken in consideration.We think Dyscolus aequinoctialis must be reestablished as a valid species, based on the following character states.

Differential diagnosis

Colour. – In every studied population with more than 10 individuals, the upper surface of head and pronotum is black or piceous black in most of them; only a few individuals may have a brownish or reddish area on the vertex and on the sides of the pronotum ( subviolaceus : integuments are never completely black, the colour varies from reddish-brown to dark brown). The elytra have a bright, metallic blue colour ( Fig. 1a), less frequently greenish-blue or purplish-blue ( subviolaceus : elytra submetallic purplish, sometimes quite dull, never bright blue).

Prothorax. – Pronotum more transverse ( Fig. 1c), PL/PW = 0.84-0.87, arithmetic mean 0.85 ( subviolaceus : PL/PW = 0.88-0.94, mean 0.91); sides strongly sinuate anterad hind angles ( subviolaceus : sinuation more variable); lateral margins more explanate distally.

Elytra. – Sides subparallel ( Fig. 1a), humeri strongly protruding ( subviolaceus : sides slightly more oval, humeri more rounded); more elongate, EL/EW = 1.73-1.84, arithmetic mean 1.78 ( subviolaceus : EL/ EW = 1.62-1.73, mean 1.66).

Legs. – Metatarsi slightly narrower, almost carinate dorsally, dorsolateral sulci sharply engraved on articles 1-4 ( Fig. 2b, red arrows) ( subviolaceus : convex dorsally, dorsolateral sulci shallower, partly erased on MTT4, Fig. 2a). Outer apical lobe of MTT4 distinctly shorter ( Fig. 2 a-b, black dotted lines).

Male genitalia. – Median shaft bisinuate in lateral view, swollen at middle ( subviolaceus : more evenly curved, almost straight at middle) ( Fig. 3 a-b); subapical carina of the ventral face of the median shaft narrower ( Fig. 3 e-f); apical blade thinner and longer ( Fig. 3 a-b, detail). Endophallus faintly squamose with a distinctly more sclerotized area, oval-shaped, on the left side of the subapical zone ( Fig. 3b) ( subviolaceus : endophallus evenly squamose, without any sclerotized area).

Habitat. – Dyscolus aequinoctialis is a riparian, fully winged species, widely distributed in the Andean humid montane forest between 1000 -2500 m a.s.l.

Geographic distribution

- Colombia (Arenas-Clavijo et al., 2022: 40, as Dyscolus subviolaceus ),

- Ecuador ( Moret, 1990: 198),

- Peru (unpublished data).

- Specimens from Venezuela, the West Indies and Mexico, mentioned by Whitehead (1973:188), may not be conspecific.

- Collection data from the Otonga Nature Reserve ( Ecuador, Cotopaxi Province): Río Esmeraldas, 1800 m, 4.VII.2001, P. Moret leg. ( CPM) ; Río Las Damas , 1800 m, 6.VII.2001, P. Moret leg. ( CPM) ; 2000 m, 14.XII. 1996, E. Tapia leg. ( CAVT) ; VII-VIII.1998, I. Tapia leg. (QCAZ); Otonga , V.1998, A.Lara leg.( QCAZ) ; Río Esmeraldas, 0°25.455’S, 79°00.360’ W, 1883 m, 13.VIII.2016; V. Crespo leg. ( CPM) GoogleMaps .

- Other provinces in Ecuador:

Imbabura, Pichincha, Sucumbíos, Napo, Chimborazo, Loja, ZamoraChinchipe (data from CPM and QCAZ) .

Taxonomic remarks. – In this study we have only examined two species-rank taxa of the subviolaceus group, those representing the populations of Brazil (Mata Atlântica) and of the equatorial Andes. A more complete revision is required to clarify the taxonomy of this supra-specific complex that is present in the Andes from Argentina to Colombia, in Venezuela, in the West Indies and in Mexico, with diversely differentiated populations that are probably the result of allopatric isolation events.

Dyscolus mendozensis ( Roig-Juñent, 2003) comb. nov., originally described as the type species of Austroglyptolenus Roig-Juñent View in CoL , is the available name for the southernmost lineage of the group. The type series of D. mendozensis contains material from the San Luis and Mendoza provinces in north-western Argentina ( Roig-Juñent, 2003: 48). Additionally, we have studied specimens collected between 1950-1975 in the Argentinian provinces of Jujuy and Tucumán, and another one labelled “Macul / Santiago de Chile ” (CPM, ex coll. Jacques Nègre). More material is needed to confirm the presence of this species in Chile. Dyscolus mendozensis shares characters both with D. subviolaceus View in CoL and D. aequinoctialis View in CoL . It has a brownish or reddish colour with faint metallic lustre on the elytra in most specimens, as subviolaceus View in CoL , and on the other hand exhibits a transverse pronotum ( Fig. 1e) and elongate elytra as aequinoctialis View in CoL . Its most distinctive character is the reduced size of the outer lobe of MTT4, which is much shorter than in D. subviolaceus View in CoL and D. aequinoctialis View in CoL ( Fig. 2c).

At the opposite, northern limit of the distribution area of the species group ( Venezuela, West Indies, Mexico), specimens are externally very similar to D. aequinoctialis View in CoL . An in-depth examination would be necessary to determine whether these populations are conspecific with D. aequinoctialis View in CoL or not. Two names, currently treated as synonyms of D. subviolaceus (Chaudoir) View in CoL , might be available if needed: Dyscolus silviae (Zayas, 1988) View in CoL , described from Cuba, and Dyscolus chalybicolor ( Chaudoir, 1878) View in CoL , described from Venezuela (see Lorenz 2019).

Diagnosis of the Dyscolus subviolaceus species group. – Fully winged; overall body length 11-15 mm; head and pronotum reddish-brown to piceous black, elytra metallic or submetallic with a purple or blue dominant colour ( Fig. 1 a-b); pronotum cordate, hind angles right-angled or slightly obtuse ( Fig. 1, c-e); elytra elongate, striae sharply marked, third interval with 3 discal setae; fourth metatarsomere with a pair of strong subapical dorsolateral setae ( Fig. 2); ventral face of the median lobe of the aedeagus with two subapical longitudinal grooves separated by a median smooth carina ( Fig. 3, e-f); bursa copulatrix with a well-developed ring of lumenal microtrichia. The position of this species group within the genus Dyscolus is supported by COI molecular evidence from a specimen of D. aequinoctialis collected in Zamora, southern Ecuador (Moret & Murienne 2021, Fig. 2, SUM 193-18, under the name Dyscolus subviolaceus ).