Stamnodes fergusoni can be immediately separated from most Stamnodes by its orange ground color and pattern of lead-gray patches across the forewing and hindwing. North of Mexico, Stamnodes fergusoni may only be confused with Stamnodes deceptiva or Stamnodes fervefactaria, neither of these species occur in southwest Texas. Although superficially close (and sometimes confused in collections), S. fergusoni can be quickly distinguished from the other two species. Stamnodes fergusoni can be reliably determined by the bright, white reticulate pattern of the underside of the hindwing and costal area of the forewing (Fig. 1b). In the other two species, the reticulate pattern of fore- and hindwing is cream to dull orange in color (Figs 2b, 3b). The frons of S. fergusoni is immediately diagnostic: the dorsal scarlet scales and ventral white scales are separated by a band of black scales (Fig. 4). Stamnodes fergusoni also differs from S. deceptiva and S. fervefactaria by its slightly larger size, lighter orange ground color, brighter scarlet scales at forewing base, and mostly scarlet tegula (Fig. 1).

Figures 1–3. 

Adult Stamnodes. 1 Stamnodes fergusoni [HOLOTYPE], TX: Val Verde Co., Ranch Road 189 (30.1823°, -100.06°), 19 September 2018, J. Vargo coll., a dorsal view, b ventral view; 2 Stamnodes fervefactaria, Colorado: El Paso Co., ssw of Colorado Springs Hwy. #115 at mkr. #30.2 Los Pinos housing entry [38.5797, -104.9308], 6480ft, 14 August 2004, Chuck Harp coll., BOLD Process ID: LNAUW1876-17, Museum ID: USNM ENT 01343267, a dorsal view, b ventral view; 3 Stamnodes deceptiva, AZ: Cochise Co., Ash Canyon Rd Huachuca Mts., 5100ft, 3 August 1999, Douglas C. Ferguson coll., BOLD Process ID: LNAUS1646-13, Museum ID: USNM ENT 00808502 a dorsal view, b ventral view.

Figures 4–6. 

Frontal view of head for Stamnodes fergusoni and related species. 4 Stamnodes fergusoni; 5 Stamnodes fervefactaria; 6 Stamnodes deceptiva.

Male genitalia (Fig. 7) are generally similar to those of S. deceptiva except for the following differences: (1) The costal sclerite is fully integrated into the valve and lacks the protruding thumb-like free end of S. deceptiva. (2) A prominent hair tuft arising from the low tubercle on the inner face of valve is approximately as long as the uncus or as long as the distance from its place of attachment to the end of the valve in S. fergusoni, but only half that length in S. deceptiva. (3) The juxta has a posterolateral pair of long, acuminate-conical processes that are lacking in S. deceptiva. (4) The vesica has ca. 30 large cornuti and many small cornuti clustered in one large group in S. fergusoni; there are two or three large and three or four small cornuti in one group, and many very small ones in another widely separate group in S. deceptiva. The male genitalia of S. fervefactaria are most similar to those of S. deceptiva except that the costal sclerite of the valve does not have a thumb-like free end and is nearly straight, not S-shaped as in S. deceptiva; the hair tuft on the valve reaches the end of the costal sclerite (but only half that distance in S. deceptiva); and the vesica has only small, poorly developed cornuti (Figs 8, 9). Female genitalia (Fig. 10) are similar to those of S. deceptiva and S. fervefactaria except for the following differences: (1) The bursa copulatrix has two widely separated signa, the one nearer to the ductus bursae is centered in a large sclerotized area and bears a single thorn-like process inwardly (on interior surface of bursa copulatrix); the other signa lacks a process; Stamnodes deceptiva has only a single nipple-like signum. (2) The ostium bursae is marked by a relatively large, strongly sclerotized, elongate, subtriangular plate (rounded anteriorly, slightly emarginate posteriorly). (3) Overall, the genitalia are ca. 1.5 × larger than those of S. deceptiva and S. fervefactaria (Figs 11, 12). The small sclerotized regions forming the bases of the signa of all species are usually depressed externally and convex internally, with or without an inner process. The signa of S. fervefactaria are reduced.

Figures 7–9. 

Male genitalia. 7 Stamnodes fergusoni (USNM58902), a genital capsule, b aedeagus with everted vesica; 8 Stamnodes fervefactaria (USNM55242), a genital capsule, b aedeagus; 9 Stamnodes deceptiva (USNM58903), a genital capsule, b aedeagus with everted vesica. Scale bars: 0.85 mm (9a), 0.25 mm (9b).

Figures 10–12. 

Female genitalia. 10 Stamnodes fergusoni (TAM-2019-001); 11 Stamnodes fervefactaria (USNM55243); 12 Stamnodes deceptiva (USNM59079). Scale bar: 1 mm.

Adult male. Forewing length: 14–16mm (Fig. 1) (N = 74). Head. Vertex scarlet, sometimes with scattered snow-white scales near base of antenna and collar; frons with dorsal scarlet and ventral white scales separated by thin transverse band of black scales; laterad black scales continued ventrad into white scaling; white scales along dorsal margin of eye. Labial palpus subequal to diameter of eye, short and slightly porrect, with exceedingly long black scales (especially near base) and sparse white intersegmental scales. Antenna filiform, laterally compressed, 0.5 length of forewing; scape mostly black, typically with small dorsal patch of white scales and several scattered white basal scales; flagellum fuscous with dorsal scales only, lateral and ventral sides bearing abundant microsetae. Collar scarlet with inconspicuous posterior white scales. Lateral patches of gray piliform scales between vertex and collar. Thorax. Mesoscutum predominantly light gray dorsally, generally trending from anterior dark gray (except white under patagium) to posterior cream-white, several individuals showing modest pink tone; ventrally bright white. Patagium scarlet; tegula mostly scarlet, basally black, and transitioning to pale, pink piliform scales posteriorly. Legs banded with fuscous and white; tibial spur formula 0–2–4. Coxae snow white. Forewing. Scarlet near base, diffusing to light orange near antemedial area (orange ground color paler than that of S. deceptiva and S. fervefactaria). Costal margin with several lead-gray patches; two small patches near base and antemedial area hugging costal margin (same patches continuous in S. deceptiva, and either singular or missing in S. fervefactaria); large trigonate to subquadranglar patch near postmedial area terminating near M₃; apical patch more or less trigonate and highly variable, extending along outer margin before terminating prior to tornus, often divided by lobe or ray of orange ground color that extends toward apex. Fringe checkered, alternating white and lead-gray. Underside patterned like upperside. Scarlet base more vibrant on costa; costal and apical areas between lead-gray patches given much more to white than on upperside; checkered fringe pattern often extending into terminal area especially near apex. Hindwing. Reticulate light-orange ground color between variable patches and spots of lead-gray (more dissected than S. fervefactaria). Inner margin basally scarlet, quickly transitioning to admixture of fuscous, light orange, and scarlet. Approximately five ill-defined lead-gray patches (clockwise from wing base): small, basal oblong patch; small, often broken, costal, triangular antemedial patch; larger, ovate postmedial patch; ovate patch at anal angle, subequal to previous; and large, irregularly triangular patch that runs along inner margin. Often with irregular lead-gray subterminal line that expands into subapical patch, connecting dark areas in fringe. Fringe checkered, lead-gray scaling reduced to almost absent in some specimens. Underside like upperside, except light-orange ground color replaced by bright white, lead-gray patches finely outlined by dark gray, basal lead-gray patch often with small scarlet spot basad. Abdomen. Dorsum fuscous, venter pale gray; small black spiracular spots. Male genitalia (Fig. 7) (N = 2) Uncus long and narrow, tapering slightly at apex. Valva broadly ovate, ca. 2 × longer than wide, outwardly convex at middle of costal margin; broadly rounded at apex; prominent hair tuft arising from low tubercle on inner face of valve approximately as long as uncus or as long as distance from its place of attachment to end of valve. Juxta U-shaped, with posterolateral pair of long, acuminate-conical processes. Aedeagus cylindrical, exceeding length of valva; base broadly rounded; apex with broad concave aperture; vesica with ca. 30 large spinose cornuti surrounded by many smaller spinose cornuti in dense cluster.

Female. Forewing length: 16–17mm (N = 9). Outwardly undifferentiated from male. Female genitalia (Fig. 10) (N = 1). Papillae anales broadly pointed and unfused posteriorly. Posterior apophysis fused with papillae anales anteriorly, long and extending to intersegment of A9 of A10; anterior apophysis one-half the length of posterior apophysis. Ostium bursae with large, ventral, strongly sclerotized, elongate, subtriangular plate (rounded anteriorly, slightly emarginate posteriorly). Ductus bursae short, sclerotized laterally, subtriangular and opening broadly into corpus bursae. Corpus bursae spheroid with two widely separated signa; signum nearer ductus bursae centered in large sclerotized area and bearing a single thorn-like process directed inward on interior surface; anterior signum without such a process and with rugose areole.

(Figs 13, 14). Coloration variable, dorsum ranging from green to lavender or mixture of both; venter yellow-green to lime-green, darker than dorsum in green forms. In cross section, venter shallowly hemispherical below white lateral stripe, appearing somewhat flattened. Upper side of white subspiracular stripe diffuse, enveloping spiracles; ventral margin more defined. Primary setae, sharp, relatively long, roughly 2.5-3 × height of spiracle, many borne from black pinaculum positioned atop minute wart. Spiracles tan to pale orange with darker peritreme. Head with circular freckles mostly clustered into tight groups over each lobe and in each corner of frons; primary setae from black pinacula; stemma 3 ca. 1.5 × stemmata 2 and 6.

Figure 13–14. 

Larvae of Stamnodes fergusoni on Salvia pinguifolia; NM: Lincoln Co., Carrizozo lava flow, DLW Lot: 2018J32, COI Barcode DLW-001425. 13 last instar; 14 penultimate instar.

Integument roughened and transversely furrowed. Extensively peppered with minute melanized patches which are most visible over each lobe of head and posterior abdominal segments (especially in cleared preparations). Prothoracic spiracle subequal to those on A1-A6 (~0.12 mm high); spiracle on A7 and A8 (~0.16 mm high). Planta of A6 with 20 or 21 secondary setae below level of SV seta, bearing 25 or 26 crochets mostly of two alternating lengths.

Holotype male , TX: Val Verde Co., Ranch Road 189 (30.1823°, -100.06°), Elev. 1676’, 19 September 2018, Jim Vargo coll. dry pinned (USNM) (Fig. 1).

Paratype adults. (52♂, 18♀): NM: Lincoln Co., Valley of Fires Recreation Area (33.67977°, -105.92708°), 11 August 2014, Black light trap, Leg. J. Luig & J. Metlevski, Voucher Codes: (363203, 363204), (2♂) (KSU-MEPAR); NM: Lincoln Co., Valley of Fires Recreation Area (33.681795°, -105.923486°), 4–5 September 2015, At light, Leg. J. Metlevski, Voucher Codes: (363197, 363198), (2♂) (KSU-MEPAR); NM: Lincoln Co., Valley of Fires Recreation Area (33.678049°, -105.927135°), 4 September 2015, Mercury vapor light, Leg. J. Metlevski, Voucher Codes: (363193–363196), (4♀) (KSU-MEPAR, TAMUIC); NM: Lincoln Co., Valley of Fires Recreation Area (33.678167°, -105.927492°), 4 September 2015, Black light trap, Leg. J. Metlevski, Voucher Codes: (363199–363202, 367370–367375), (9♂, 1♀) (TAMUIC, USNM, AMNH); TX: Uvalde Co., Concan, 9 November 2015, Ed Knudson coll., (1♂)(UCMS); TX: Uvalde Co., Concan, 28 September 2013 – 1 October 2013, Ed Knudson & Charles Bordelon colls., (1♂, 1♀) (UCMS); TX: Edwards Co., 1.2 km NW Camp Wood [29.6822°, -99.9711°], 13 October 2017, Ann Hendrickson coll., (3♂) (UCMS); TX: Val Verde Co., Seminole Canyon State Park, 20 October 1985, John Rawlins coll., BOLD Process IDs: LNAUV1793-17, LNAUV450-16, Museum IDs: USNM ENT 01276376, 01237649, Genitalic Slide DCF1651, (1♂, 1♀) (USNM); TX: Val Verde Co., Ranch Road 189 (30.1823°, -100.06°), 19 September 2018, Jim Vargo coll. (1♂, 1♀)(USNM); TX: Val Verde Co., (29.696°, -101.324°), 25 October 2014, Jim Vargo coll. (1♀)(TAMUIC); TX: Val Verde Co., Del Rio, 4 October 1994, Ed Knudson coll., (25♂, 7♀)(MGCL); TX: Uvalde Co., ConCan, 15 October 2001, G. Muise coll., (2♂, 1♀)(MGCL); TX: Uvalde Co., ConCan, 19 October 2000, Ed Knudson coll., (1♂)(MGCL); TX: El Paso Co., Franklin Mts., 17 September 1993, Ed Knudson coll., (3♂)(MGCL); TX: Val Verde Co., Dolan Falls Devil’s River, 3–10 October 1994, J. Gillaspy coll., (1♀)(MGCL); TX: Kinney Co., Bracketville, 5 October 1994, Ed Knudson coll., (1♂)(MGCL).

Adults. TX: (County Unknown), Langley [Langtry], 25 October 1945, (collector unknown), BOLD Process ID: LNAUV1794-17, Museum ID: USNM ENT 01276377, Genitalic Slide USNM58902, (1♂) (USNM); TX: Val Verde Co., Seminole Canyon State Park, 20 October 1985, John Rawlins coll., (damaged by museum pests) (1♂) (USNM); TX: Culberson Co., Guadalupe Mountains National Park north McKittrick Canyon, 28 March 1968, Roy O. Kendall & C. A. Kendall coll., (1♂) (MGCL); NM: Catron Co., Gila National Forest, Forest rd. 94 (33.7181°, -108.4683°), 20 August 2015, Elev. 8200’, Ron Parry coll. (from photograph). Additional internet photographic records (mapped in Figure 15) from iNaturalist (https://www.inaturalist.org/observations/): 18390285, 18339093, 9176399, 8832387, 8819801, 8813547, 8801663, 8795069, 8367680, 2360810. BugGuide observations (https://bugguide.net/node/view/): 1322692, 1493681, 1456212, 713503. Larvae. NM: Lincoln Co., Carrizozo lava flow, 16 September 2018, DLW Lot: 2018J32 & 2018J35, Tanner Matson & David Wagner coll., BOLD Process ID: WAGL1235-18, beaten from Salvia pinguifolia (N = 5) (UCMS); AZ: Cochise Co., Warren, 23 September 2018, DLW Lot: 2018J133, Tanner Matson, David Wagner, & Mimi Kamp coll., BOLD Process ID: WAGL1401-19, beaten from Salvia pinguifolia (N = 1) (UCMS).

Figure 15. 

Distribution of Stamnodes fergusoni (N = 90, red). Single dots may represent > 1 individual. Scale bar: 200 km.

(Fig. 15) Southwest Hill Country (Uvalde, Kinney, Edwards, and Val Verde counties); Franklin Mountains (Franklin County); and Guadalupe Mountains (Culberson County) of Texas (Knudson and Bordelon 2002, and this paper). Carrizozo Malpais lava flow (Lincoln County), New Mexico (where it is abdundant); also Gila National Forest (Catron County), New Mexico (https://southwesternmoths.com). Mule Mountains (Cochise County) of extreme southeastern Arizona. Range into Mexico remains unclarified; we have examined several collections from the north Coahuilan hill country near Ciudad Acuña.

The species is named in honor of the late Douglas C. Ferguson, a reigning and much respected authority on the geometrid fauna of North America for more than four decades. Dr. Ferguson’s notes, dissections, and collections were valuable assets that guided this effort. Dr. Ferguson was in the process of describing this species before his passing (Knudson and Bordelon 2002) (pers. comm. Charles Covell; Alma Solis).

The larvae are believed to be specialists on woody Salvia (Lamiaceae). Stamnodes fergusoni larvae were collected and reared to maturity on Salvia pinguifolia (rock sage) from Carrizozo Malpais, New Mexico (BOLD Process ID: WAGL1235-18, BOLD Sample ID: DLW-001425). A middle instar larva was collected from Salvia pinguifolia in Warren, Arizona (BOLD Process ID: WAGL1401-19, BOLD Sample ID: DLW-001401). In the Southwestern Hill Country of Texas, the species is believed to feed on Salvia ballotiflora (shrubby blue sage) as this is the only woody Salvia at the localities where this species has been taken.

The larvae of S. fergusoni were first discovered on Salvia pinguifolia plants growing at the bottom of large gas bubbles that formed during the deposition of the Carrizozo Malpais lava field, west of Carrizozo, New Mexico. When the top of a bubble erodes away, the remaining volcanic pit acts as a catch basin for rain and dust, and over time comes to support diverse gardens in an otherwise black ultraxeric landscape. Larvae were found on plants growing within these bubbles, especially where overhanging lava shelves shield plants from full sun. Smaller, water-stressed plants growing in full sun yielded no S. fergusoni larvae. The purple pigments in the caterpillar appear to be derived from the flowers of its host (Fig. 13). In the laboratory, caterpillars were observed with their bodies deeply inserted into the calyx of individual flowers, feeding on reproductive tissues and callow seeds. The caterpillars of S. deceptiva and S. fervefactaria are so far unknown; we suspect they are using other Lamiaceae.

Stamnodes fergusoni has a single late-summer generation that appears to be tied to the flowering time of its preferred host. The moth is locally common in New Mexico and southwestern Hill Country of Texas with peak adult activity in September and October. Adults fly earlier (first weeks of September) in New Mexico. Several worn individuals were taken in March (2002) from the Guadalupe Mountains, by Roy Kendall. Knudson and Bordelon (2002) believed this collection represented overwintering adults. Mature larvae pupate in leaf litter or over soil. Over most of the species’ range, the pupa is believed to overwinter and remain in diapause until the following fall.