Acronyctodes asignum Matson

Figures 1, 5, 16, 21, 26, 34.

https://zoobank.org/NomenclaturalActs/63779c9a-f7f0-416e-a29a-eeacf114b07b

Diagnosis. Acronyctodes asignum cannot be reliably distinguished from A. cautama, A. colorata, and A. corrugata based on external appearance. Confidence in identification typically requires genitalic dissection and/or DNA barcoding. Our limited sampling suggests that A. asignum primarily inhabits the Guanacaste and Central Cordilleras of Costa Rica, while A. colorata is found in the Talamanca Cordillera of Costa Rica and Panama, and A. corrugata ranges more widely across the Central American montane and pine-oak forests of southern Mexico, Guatemala, El Salvador, Honduras, and possibly Nicaragua. Acronyctodes cautama is thus far only known from Mexico, west of the Isthmus of Tehuantepec.

The female genitalia of A. asignum are immediately diagnostic among the known members of the Cautama-group, as it is the only member lacking a signum on the corpus bursae (Fig. 21). In contrast, the male genitalia are less distinctive and often exhibit transitional characteristics towards other members of the Cautama-group, necessitating caution when using them as definitive identifiers. However, there appears to be notable differences in the arrangement and number of cornuti among the species. Acronyctodes asignum typically has 12–15 cornuti arranged in a mostly linear fashion on the vesica (Fig. 16b). In comparison, A. colorata usually has 30–35 cornuti in a dense non-linear cluster (Fig. 19b), A. corrugata has 10–15 cornuti in a mostly linear cluster (Fig. 17b), A. cautama has 7–10 in a linear cluster (Fig. 18b), and A. bisbili has approximately 25–30 cornuti in a non-linear cluster (Fig. 20b). Additionally, the apex of the valve in A. asignum, A. corrugata, and A. cautama is slightly angulated, whereas in A. bisbili and A. colorata, it appears entirely rounded (Figs. 16a–20a).

Adult. (Figure 5). Forewing length: male: 18–22 mm; female: 23–26 mm.

Head: Antenna bipectinate in both sexes; rami of male about 3x longer than those of female; scales above ochreous with scattered black scales. Frons and vertex ochreous gray. Labial palpus 1.5x diameter of eye, ochreous gray. Haustellum well-developed.

Thorax: Tan to ochreous gray. Legs tan to ochreous gray, mottled with dark gray to black patches. Males with small hair pencil tucked inside groove on inner surface of hind tibia. Epiphysis well-developed. Tibial spur formula 0-2-4. Forewing grayish tan, variable amounts of brown and olive green; smooth antemedial line, modestly dentate postmedial line. Medial area between antemedial and postmedial lines slightly browner. Black discal spot present and post-discal area near discal spot with blackened patch. Subtle, diffused darkened medial line sometimes present near postmedial line. Hindwing grayish-tan with transverse medial black dentate line and black discal spot; discal spot may have additional subtle transverse line through it. Underside of both wings like upperside but with pattern elements more spotty and color highly variable. Fringe sometimes with light checkering.

Abdomen: Pale gray to tan.

Male genitalia: (Figure 16). Uncus triangulate and campanulated, ending in hood-like apex. Medial posterior projection of gnathos papillated. Valve broad with costal sclerite ending in subapical acuminate process. Juxta plate-like with large posterior digitate process. Vesica with ca. 12–15 spinose cornuti in tight, mostly linear, cluster.

Female genitalia: (Figure 21). Posterior apophysis ca. one half length of anterior apophysis.

Ductus bursae with anterior sclerite. Corpus bursae ovate and entirely membraneous; signum absent.

Larva: (Figure 26). Head black with white suture separating frons and lobes; clypeus white. Body predominantly jet black, with mottled orange markings throughout thorax and A1, and at posterior end from A6 onward. Broken middorsal and subdorsal white pinstripes extend primarily across A1–A5, transitioning to yellow toward front and rear of body. Spiracles black; spiracular area with large, ill-defined white and yellow streaked patches, interspersed with scattered black spots, particularly over A2–A5. Prolegs yellow and black.

Phenotype somewhat resembling A. cautama, but that species typically features a broad, mostly continuous white spiracular band across the mid-body. Additionally, the thorax and posterior body of A. cautama are less mottled with black and yellow and instead exhibit crisper, more defined black patches over the yellow areas.

Holotype. ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 07-IV-2016, coll. Sergio Rios, Genitalia slide: TAM-2023-329, 16-SRNP-101701, USNMENT01947536, [USNM].

Paratypes (39♂, 24♀). ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Manta Claro, (10.80345°, - 85.32621°), el. 1610m, 03-III-2011, coll. F. Quesada and H. Cambronero, 11-SRNP-101352, USNMENT01947497; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 15-VI-2018, coll. S. Rios and H. Ramirez, 18-SRNP-104265, USNMENT01947498; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Manta Claro, (10.80345°, -85.32621°), el. 1610m, 02-II-2011, coll. S. Rios and R. Franco, 11-SRNP-100639, USNMENT01947499; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Manta Claro, (10.80345°, -85.32621°), el. 1610m, 02-II-2011, coll. S.Rios and R.Franco,11-SRNP-100638,USNMENT01947500; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 06-IV-2016, coll. Sergio Rios, 16-SRNP-101407, USNMENT01947501; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 06-IV-2016, coll. Sergio Rios, 16-SRNP-101408, USNMENT01947502; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 15-VI-2018, S. Rios and H. Ramirez, 18-SRNP-104264, USNMENT01947503; ♀, COSTA RICA: Guanacaste, ACG, Cacao, Derrumbe, (10.93110°, -85.46194°), el. 1310m, 11-VII-2010, coll. R. Franco and F. Quesada, 10-SRNP-110975, USNMENT01947504; ♀, COSTA RICA: Guanacaste, ACG, Cacao, Sendero Cima, (10.93328°, -85.45729°), el. 1460m, On Schlegelia parviflora, 25-VI-2018, ecl. 02-VIII-2018, coll. Dunia Garcia, 18-SRNP-35309, USNMENT01947505; ♀, COSTA RICA: Guanacaste, ACG, Cacao, Sendero Cima, (10.93328°, -85.45729°), el. 1460m, On Schlegelia parviflora, 25-VI-2018, ecl. 17- VIII-2018, coll. Dunia Garcia, 18-SRNP-35310, USNMENT01947506, [missing abdomen]; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 01-IV-2017, coll. S. Rios, 17-SRNP-102033, USNMENT01947507; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 17-XI-2017, coll. S. Rios and H. Ramirez, 17-SRNP-106962, USNMENT01947508; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 01-IV-2017, coll. S. Rios, 17-SRNP-102028, USNMENT01947509; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 01- IV-2017, coll. S. Rios, 17-SRNP-102029, USNMENT01947510; ♀, COSTA RICA: Guanacaste, ACG, Cacao, Sendero Cima, (10.93328°, -85.45729°), el. 1460m, On Schlegelia parviflora, 27-V-2009, ecl. 06-VIII-2009, coll. Harry Ramirez, 09-SRNP-35911, USNMENT01947511; ♂, COSTA RICA: Guanacaste, ACG, Cacao, Sendero Cima, (10.93328°, -85.45729°), el. 1460m, On Schlegelia parviflora, 08-IX-2010, ecl. 26-X-2010, coll. Manuel Pereira, 10-SRNP-36350, USNMENT01947512; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 01-IV-2017, coll. S. Rios, 17-SRNP-102026, USNMENT01947513; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 01-IV-2017, coll. S. Rios, 17-SRNP-102027, USNMENT01947514; ♀, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 23- VII-2017, coll. S. Rios, 17-SRNP-105361, USNMENT01947515; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 01-IV-2017, coll. S. Rios, 17-SRNP-102025, USNMENT01947516; ♀, COSTA RICA: Guanacaste, ACG, Cacao, Sendero Cima, (10.93328°, - 85.45729°), el. 1460m, On Schlegelia parviflora, 12-IX-2018, ecl. 03-XI-2018, coll. Harry Ramirez, 18-SRNP-35513, USNMENT01947517; ♀, COSTA RICA: Guanacaste, ACG, Cacao, Sendero Cima, (10.93328°, -85.45729°), el. 1460m, On Schlegelia parviflora, 12-IX-2018, ecl. 13-XI-2018, coll. Harry Ramirez, 18-SRNP-35525, USNMENT01947518; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 28-IV-2017, coll. S. Rios, 17-SRNP-102774, USNMENT01947519; ♀, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 22- VII-2017, coll. S. Rios, 17-SRNP-105083, USNMENT01947520; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 31-III-2017, coll. S. Rios, 17-SRNP-101872, USNMENT01947521; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 31-III-2017, coll. S. Rios, 17-SRNP-101873, USNMENT01947522; ♀, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 07-II-2016, coll. R. Franco and H. Cambronero, 16-SRNP-100096, USNMENT01947523; ♀, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 07-II-2016, R. Franco and H. Cambronero, 16-SRNP-100097 USNMENT01947524; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 21-VII-2017, coll. S. Rios, 17-SRNP-104659, USNMENT01947525; ♂, COSTA RICA: Guanacaste, ACG, Cacao, Sendero Cima, (10.93328°, -85.45729°), el. 1460m, On Schlegelia parviflora, 12-IX-2018, ecl. 03-XI-2018, coll. Harry Ramirez, 18-SRNP-35515, USNMENT01947526; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 21-VII-2017, coll. S. Rios, 17-SRNP-104657, USNMENT01947527; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 21-VII-2017, coll. S.Rios, 17-SRNP-104658, USNMENT01947528; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 16-IV-2018, coll. S. Rios, 18- SRNP-102007, USNMENT01947529; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 07-II-2016, coll. R. Franco and H. Cambronero, 16-SRNP-100095, USNMENT01947530; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 01-IV-2017, coll. S. Rios, 17-SRNP-102024, USNMENT01947531; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 07- IV-2016, coll. Sergio Rios, 16-SRNP-101702, USNMENT01947533; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 07-IV-2016, coll. Sergio Rios, 16- SRNP-101703, USNMENT01947534; ♀, COSTA RICA: Guanacaste, ACG, Cacao, Sendero Cima, (10.93328°, - 85.45729°), el. 1460m, On Schlegelia parviflora, 17-VII-2008, ecl. 27-VIII-2008, coll. Harry Ramirez, 08-SRNP-36083, USNMENT01947537; ♀, COSTA RICA: Guanacaste, ACG, Cacao, Sendero Cima, (10.93328°, -85.45729°), el. 1460m, On Schlegelia parviflora, 27-V-2009, ecl. 31-VII-2009, coll. Harry Ramirez, Genitalia slide: TAM-2023- 328, 09-SRNP-35908, USNMENT01947538; ♀, COSTA RICA: Guanacaste, ACG, Cacao, Sendero Cima, (10.93328°, -85.45729°), el. 1460m, On Schlegelia parviflora, 08-IX-2008, ecl. 24-XI-2008, coll. Manuel Pereira, 08-SRNP-36802, USNMENT01947539; ♂, COSTA RICA: Guanacaste, ACG, Cacao, Sendero Cima, (10.93328°, -85.45729°), el. 1460m, On Schlegelia parviflora, 08-IX-2008, ecl. 20-XI-2008, coll. Manuel Pereira, 08-SRNP-36798, USNMENT01947540; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Manta Sendero Perdido, (10.80639°,-85.32158°),el. 1762m, 03.III.2011, coll. S.Rios and R.Franco,11-SRNP-101286,USNMENT01947541; ♂, COSTA RICA: Guanacaste, ACG, Cacao, Derrumbe, (10.93110°, -85.46194°), el. 1310m, 10-VII-2010, coll. S. Rios and H. Cambronero, Genitalia slide: TAM-2023-327, 10-SRNP-110548, USNMENT01947542; ♀, COSTA RICA: Guanacaste, ACG, Cacao, Sendero Cima, (10.93328°, -85.45729°), el. 1460m, On Schlegelia parviflora, 19- X-1998, ecl. 11-XII-1998, coll. Mariano Pereira, 98-SRNP-15622, USNMENT01947543; ♀, COSTA RICA: Guanacaste, ACG, Cacao, Sendero Cima, (10.93328°, -85.45729°), el. 1460m, On Schlegelia parviflora, 12-X-1998, ecl. 16-XI-1998, coll. Mariano Pereira,98-SRNP-15511,USNMENT01947544; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Manta Claro, (10.80345°, -85.32621°), el. 1610m, 02-II-2011, coll. S. Rios and R. Franco, 11- SRNP-100640, USNMENT01947545; ♀, COSTA RICA: Guanacaste, ACG, Cacao, Sendero Cima, (10.93328°, - 85.45729°), el. 1460m, On Schlegelia parviflora, 27-V-2009, ecl. 12-VIII-2009, coll. Harry Ramirez, Genitalia slide: TAM-2023-330, 09-SRNP-35909, USNMENT01947546; ♀, COSTA RICA: Guanacaste, ACG, Cacao, Sendero Cima, (10.93328°, -85.45729°), el. 1460m, On Schlegelia parviflora, 27-V-2009, ecl. 02-VIII-2009, coll. Harry Ramirez, 09-SRNP-35910, USNMENT01947547; ♀, COSTA RICA: Guanacaste, ACG, Cacao, Sendero Cima, (10.93328°, -85.45729°), el. 1460m, On Schlegelia parviflora, 20-IX-1999, ecl. 09-XI-1999, coll. Mariano Pereira, 99-SRNP-1614, USNMENT01947548; ♂, COSTA RICA: Guanacaste, ACG, Cacao, Sendero Cima, (10.93328°, -85.45729°), el. 1460m, On Schlegelia parviflora, 08-IX-2008, ecl. 08-XI-2008, coll. Manuel Pereira, 08-SRNP-36800, USNMENT01947549; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Manta Sendero Perdido, (10.80639°, -85.32158°), el. 1762m, 02-II-2011, H. Cambronero and F. Quesada, 11-SRNP-100558, USNMENT01947550; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 08-II-2016, coll. H. Cambronero and S. Rios, 16-SRNP-100362, USNMENT01947551; ♂, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 08-II-2016, coll. H. Cambronero and S. Rios, 16-SRNP-100361, USNMENT01947552; ♀, COSTA RICA: Guanacaste, ACG, Cacao, Sendero Cima, (10.93328°, -85.45729°), el. 1460m, On Schlegelia parviflora, 21-X-1997, ecl. 02-XII-1997, coll. Roster Moraga, 97-SRNP-1910, USNMENT01947553; ♀, COSTA RICA: Guanacaste, ACG, Cacao, Sendero Cima, (10.93328°, -85.45729°), el. 1460m, On Schlegelia parviflora, 21-X-1997, ecl. 22-XI-1997, coll. Roster Moraga, 97-SRNP-1911, USNMENT01947554; ♂, COSTA RICA: Guanacaste, ACG, Cacao, Sendero Cima, (10.93328°, -85.45729°), el. 1460m, On Schlegelia parviflora, 12-X-1998, ecl. 22-XI-1998, coll. Mariano Pereira, 98-SRNP-15512, USNMENT01947555; ♀, COSTA RICA: Guanacaste, ACG, Santa Maria, Crater Bosque Sendero Adentro, (10.80348°, -85.32729°), el. 1594m, 08-II-2016, coll. H. Cambronero and S. Rios, 16-SRNP-100363, USNMENT01947556; ♀, COSTA RICA: Guanacaste, ACG, Cacao, Sendero Cima, (10.93328°, -85.45729°), el. 1460m, On Schlegelia parviflora, 25-VI-2018, ecl. 02-IX-2018, coll. Dunia Garcia, 18-SRNP-35311, USNMENT01947557; ♀, COSTA RICA: Guanacaste, ACG, Cacao, Sendero Cima, (10.93328°, -85.45729°), el. 1460m, On Schlegelia parviflora, 12-IX-2018, ecl. 04-XI-2018, coll. Harry Ramirez, 18-SRNP-35518, USNMENT01947558; ♀, COSTA RICA: Guanacaste, ACG, Cacao, Sendero Cima, (10.93328°, -85.45729°), el. 1460m, On Schlegelia parviflora, 12-IX-2018, ecl. 10-XII-2018, coll. Harry Ramirez, 18-SRNP-35517, USNMENT01947559; ♂, COSTA RICA: Guanacaste, ACG, Cacao, Sendero Cima, (10.93328°, -85.45729°), el. 1460m, On Schlegelia parviflora, 22-IX-1998, ecl. 30-X-1998, coll. Harry Ramirez, 98-SRNP-3700, USNMENT01980000; ♀, COSTA RICA: Guanacaste, ACG, Cacao, Sendero Cima, (10.93328°, -85.45729°), el. 1460m, On Schlegelia parviflora, 08-IX-2008, ecl. 29-XI-2008, coll. Manuel Pereira, 08-SRNP-36799, USNMENT01980001; ♂, COSTA RICA: Alajuela, ACG, Rincon Rain Forest, Wege, (10.96864°, -85.32046°), el. 385m, 19-III-2018, coll. R. Franco and H. Cambronero, 18-SRNP-101406, USNMENT01980002; ♂, COSTA RICA: Guanacaste, ACG, Cacao, Sendero Cima, (10.93328°, -85.45729°), el. 1460m, On Schlegelia parviflora, 28- IX-1998, ecl. 04-XI-1998, coll. Harry Ramirez, 98-SRNP-3836, USNMENT01980002.

Distribution. (Fig. 34). Acronyctodes asignum has been documented in the Central and Guanacaste Cordilleras of Costa Rica, found at elevations ranging from 1300 to 1800 meters (approximately 4200 to 5900 feet).

Biology. Daniel Janzen, Winnie Hallwachs, and ACG parataxonomists, have found 73 wild caterpillars of this species feeding on Schlegelia parviflora (Oerst.) Monach. (Schlegeliaceae), occasionally classified in Scrophulariaceae. To date, this plant remains the sole confirmed food record for this caterpillar, despite the presence of related plant genera in the vicinity.

Etymology. The specific epithet asignum recognizes the absence (“a-” for “without”) of a signum in the female genitalia, distinguishing this species from visually similar known congeners.

Molecular data. Sixty-six specimens of A. asignum (BOLD BIN: BOLD:AAC1083) have been DNA barcoded, revealing a pairwise distance of approximately 3% from nearest-neighbor, A. colorata (BOLD BIN: BOLD: AAJ6454).