Thereus chontachaca Faynel, Fåhraeus & González-Mercado, 2025

Thereus chontachaca Faynel, Fåhraeus & González-Mercado sp. nov.

LSIDurn:lsid:zoobank.org:act: A93D3364-3753-40AB-8BD7-2A2EFEF3D192

Figures 16, 17 View FIGURES 2–17 , 42 View FIGURES 34–49 , 58 View FIGURES 50–59 , 72 View FIGURES 66–77 , 88 View FIGURES 88–89

Type material. Holotype male ( Fig. 16 View FIGURES 2–17 ), FW: 13.3 mm, labelled as “ Pérou - Cusco // Carretera Manu, Km 89 // Chontachaca , 772 m // Réserve Tierra Linda // Poste 12h10 à 2m 50 // S 13°00.172' - O 71°27.849' // 4.VIII.2021 C. Faynel leg” (white rectangular label, black printed); “CF-LYC-1635” (orange rectangular label, black printed); “ Holotype ♂ // Thereus chontachaca // Faynel, Fåhraeus & González-Mercado, 2025” (red rectangular label, black printed). Currently in RCCF, the holotype will be deposited in MUSM.

Paratypes ( 4♂, 1 ♀). PERU. Cusco . 1♂, same data as holotype, CF-LYC-1633* ( RCCF) ; 1♂, same data as holotype ( RCCF) ; 1♂, same locality as holotype, 3.viii.2021, 12:10pm at 2m 50 ( RCCF) ; 1♂, same locality as holotype, 22.ix.2021, 12:45pm, CF-LYC-1881*, gen. prep. K. Florczyk CFCF024 ( RCCF) ; 1♀, same locality as holotype, 3-4.viii.2021, CF-LYC-1777*, gen. prep. K. Florczyk CFCF025 ( RCCF) .

Paratypes have the following labels “ Paratype ♂ [or ♀] // Thereus chontachaca // Faynel, Fåhraeus & González-Mercado, 2025” (blue rectangular label, black printed).

Diagnosis and description. T. chontachaca sp. nov. is close externally and genetically ( Fig. 1 View FIGURE 1 ) to its sister species Thereus ramirezi sp. nov. but differs from it by: (1) male DFW scent patch and scent pad proportionally much smaller when adjusted for equal wingspan ( Figs 42, 43 View FIGURES 34–49 ); (2) dorsal process supporting the brush organs not wave-shaped like in the male genitalia of Thereus ramirezi sp. nov. ( Figs 58, 59 View FIGURES 50–59 arrow); (3) 2.77% mean genetic divergence ( Table 3). Male ( Fig. 16 View FIGURES 2–17 ). FW length: 13.2 mm (n = 5). Wings. This species is one of the smallest newly described taxa. DFW dull blue basal part, large black apex (half wing). Male genitalia ( Fig. 58 View FIGURES 50–59 ). One male dissected. Global shape similar to T. genena , but longer valvae, smaller dorsal brush organs in lateral view and saccus wider in ventral view. Eighth tergite almost square, with straight posterior border and convex anterior one. Female ( Fig. 17 View FIGURES 2–17 ). FW length: 14.3 mm (n = 1). Wings. brown dorsally, beige-brown ventrally but lighter than male, same ventral patterns. Female genitalia ( Fig. 72 View FIGURES 66–77 ). One female dissected. Global shape similar to other species. Ostium bursae and ductus bursae quite aligned. Ductus bursae wide in ventral view. No signum in corpus bursae. Eighth tergite subrectangular. No sclerotized invaginations on membrane attached to ventro-lateral sides of papillae anales. The association of the sexes was based on identical type locality, similar ventral wing patterns, the same COI sequence (same BIN AEO6309).

Ethology. Males have a territorial activity at midday. In August 2021, several males were flying and fighting in a sunny place (four catches at 12:10 am) in front of the lodge of Tierra Linda reserve on the top and around an isolated Citrus tree 2.5 m high (not easy to catch with the thorns of the Citrus tree). The lodge is located in an open area, near a river and surrounded by forest. In September 2021, three males were flying 20 m behind the lodge in a sunny forest clearing (one catch at 12:45 am). They alternated between an observation post on a shrub similar in size to the previous Citrus tree ( Rutaceae ) and located in the middle of the clearing and a higher position on a nearby tree. No male was observed in their previous observation post, while the Citrus tree was still in front of the lodge.

Sympatry. T. chontachaca sp. nov. is allopatric with its sister species T. ramirezi sp. nov. and more distantly related T. borbaensis sp. nov., based on the known distribution ( Fig. 88 View FIGURES 88–89 ).

Known distribution ( Fig. 88 View FIGURES 88–89 ). Peru.

Etymology. Tierra Linda is a private voluntary reserve located near the Chontachaca village, in the valley of the Rio Cosñipata ( Peru, Cusco). It was created by José and Pilar Vicens to welcome volunteers in ecology but now belongs to Kety Paredes. The name of the new species refers to the Chontachaca village. It is a noun in apposition, not latinized.

Remarks. This species is only known from the type-locality in Peru, Cusco, Rio Cosñipata valley, about 800 m. The old-growth secondary rainforest found near Chontachaca was well conserved until 2019 but unfortunately large areas were cut for agriculture recently (Faynel pers. obs.). The species was not recorded in the study of the butterfly fauna of this valley ( Lamas et al. 2021). Jhon Harryson González-Mercado (Universidad Nacional San Antonio Abad del Cusco, Cusco, Peru) recently transformed the house of José and Pilar Vicens in Chontachaca into a center for entomological research.