Research Article |
Corresponding author: Tanner A. Matson ( tanner.matson@uconn.edu ) Academic editor: Christian Schmidt
© 2019 Tanner A. Matson, David L. Wagner, Scott E. Miller.
This is an open access article distributed under the terms of the CC0 Public Domain Dedication.
Citation:
Matson TA, Wagner DL, Miller SE (2019) A Revision of North American Lactura (Lepidoptera, Zygaenoidea, Lacturidae). ZooKeys 846: 75-116. https://doi.org/10.3897/zookeys.846.31953
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The Lactura Walker, 1854 fauna north of Mexico is revised. Six species are documented, one new species Lactura nalli Matson & Wagner, sp. n. is described, and two new synonymies are proposed: Lactura psammitis (Zeller, 1872), syn. n. and L. rhodocentra (Meyrick, 1913), syn. n. One new subspecies Lactura subfervens sapeloensis Matson & Wagner, ssp. n. is also described. Adult and larval stages, male and female genitalia, are illustrated, a preliminary phylogeny is presented based on nuclear and mitochondrial data, distribution records provided for verified specimens, and the biology and life history for each species is briefly characterized. Phylogenetic analyses, larval phenotypes, and life history information reveal that much of the historic taxonomic confusion rampant across this group in North America traces to the phenotypic variation in just one species, L. subfervens (Walker, 1854).
CO1, DNA barcodes, gum bully, subspiracular gland, Sapotaceae, Sideroxylon, tropical burnet moths
Lacturidae (tropical burnet moths) are a tropical and sub-tropical family of Zygaenoidea. Prior to the family description by
The most recent checklist of North American Lepidoptera (found north of Mexico) recognizes six species of Lactura (
Our collections of wild Lactura caterpillars and reared ex-ova cohorts from across the southeastern US and Texas have revealed six distinct larval phenotypes. These were found to align with CO1 haplotype clusters (
Fresh adult collections were obtained by light trapping with UV and mercury-vapor lights. Larvae were collected from Sideroxylon (Sapotaceae). Additional larval specimens were reared from ova deposited by gravid females. We examined the Nearctic Lactura holdings of the following museums:
ECK Edward C Knudson, personal collection, Houston, TX
JKA James K Adams, personal collection, Dalton, GA
JRM James R McDermott, personal collection, College Station, TX
KSU-MEPAR Kansas State University–Museum of Entomological and Prairie Arthropod Research, Manhattan, KS
MEM Mississippi Entomological Museum, Mississippi State, MS
Photographs from BugGuide, iNaturalist, Moth Photographers Group, and Barcode of Life Database (
CO1 barcodes for North American Lactura were compiled from holdings in the following institutions and personal collections: (CNC) Canadian National Collection of Insects, Arachnids, and Nematodes,
Seven single-copy genes capable of resolving phylogenetic relationships of Lepidoptera were sampled (5508 bp total): cytochrome c oxidase subunit 1 (CO1) from the mitochondrial genome and elongation factor–1 α (EF–1α), glyceraldehyde–3–phosphate dehydrogenase (GAPDH), isocitrate dehydrogenase (IDH), cytosolic malate dehydrogenase (MDH), sorting nexin–9–like protein (Nex9), and ribosomal protein S5 (RpS5) from the nuclear genome (
Specimen voucher data and GenBank accession numbers for samples used in phylogenetic analysis. Dash indicates DNA markers that did not amplify.
Outgroup Zygaenoidea included Adscita statices Linnaeus (Zygaenidae), Strigivenifera venata Aurivillius (Limacodidae), and Dalcerides gugelmanni Dyar (Dalceridae), as well as another lacturid, Anticrates Meyrick. Sequences were partitioned by locus and codon position. The best-fit model of nucleotide substitution for each partition was found using the Akaike Information Criterion in PARTITIONFINDER2 (
Lactura dives Walker, 1854: 485.
Medium-sized (wingspan 17–26 mm) with respect to other members of the family. Body salmon red. Head. Antenna filiform in both sexes; labial palpus porrect, maxillary palpus small. Thorax. Adult forewing elongate and subquadrangular, widest at 2/3, and typically satin white or white with speckled brown or red maculation. Oblique antemedial and postmedial rows of red or black spots often present. Apex broadly rounded and little differentiated from outer margin, bounded within R4 and R5; likewise, tornus poorly differentiated. Forewing discal cell with areole; R, M, and Cu veins sessile; CuA veins running to tornus; A1 and A2 fused from basal quarter to inner margin; A3 absent. Hindwing oval quadrate and uniformly pink-red or red-orange with elongate fringe scales. Frenulum 1/5 the size of hindwing length; wing apex poorly defined, bounded within Rs and M1; R, M, and Cu veins sessile; vannal area greatly enlarged; distinct fold between A1+A2 and A3. Venation as in Fig.
(Figs
(Figs
(Figs
(Fig.
(Figs
Lactura are difficult to rear, often molding or desiccating as prepupae. We have had modest success rearing larvae in vials with a deep (3–5 cm), occasionally moistened, layer of peat or coir.
Larvae secrete a tacky exudate from their integument to which feculae adhere and often remain attached until the next molt. We suspect the exudate is a deterrent to ants and other invertebrates, as such sticky secretions have been shown to be in the caterpillars of the related Dalceridae (
We suspect adult Lactura sometimes disperse from their natal colonies, given that several collection records appear to be out of range, e.g., a single L. rubritegula from Houston, Texas (Fig.
1 | White forewing with black dashes, spots, or streaks; light red scales on vertex | 2 |
– | White forewing with series of red or brown dashes, spots, or streaks; white scales one vertex | 3 |
2 | Forewing with black scaling over veins in upper half of forewing extending around the apex and terminating about tornus; two oblong antemedial spots and three oblong postmedial spots; absent from southern Texas |
Lactura pupula (Fig. |
– | Forewing without black scaling over veins; contiguous series of black antemedial and postmedial spots and black subcostal dash; from southern Texas |
Lactura atrolinea (Fig. |
3. | Tegula with inconspicuous red scale patch at base (below plane of forewing), otherwise white; forewing entirely white (apart from antemedial and postmedial spots); red subcostal dash often present at base of FW; from southern Texas |
Lactura basistriga (Fig. |
– | Tegula basally and medially red (extending well above plane of forewing); forewing with or without scattered red or brown scales (apart from antemedial and postmedial spots); subcostal dash absent at base of FW; absent from extreme southern Texas | 4 |
4 | Forewing with scattered red/brown scales (variable in density); antemedial and postmedial spots present but sometimes reduced; patagium white; widespread across portions of Midwest and southeastern US |
Lactura subfervens (Figs |
– | Forewing without scattered red/brown scales; antemedial and postmedial spots present; patagium with red scales near collar; west central Texas |
Lactura rubritegula (Figs |
1 | Dorsum darkly pigmented: gray, black, or brown | 2 |
– | Dorsum without gray, black, or brown pigmentation | 3 |
2 | From extreme southern Texas (Hidalgo and Cameron Counties) | 4 |
– | Absent from extreme southern Texas | 5 |
3 | Ground color green, green semitransparent dorsum; from western end of Rio Grande Valley of Texas |
Lactura nalli (Figs |
– | Ground color frosty, white stripes over dorsum; widespread across southern Midwest and southeast US, absent from Rio Grande Valley of Texas |
Lactura subfervens (Fig. |
4 | Dorsum with yellow middorsal stripe and green addorsal stripe; conspicuous metallic blue warts |
Lactura atrolinea (Fig. |
– | Variable dark coloration over dorsum interrupted by wavy, white addorsal stripe; conspicuous yellow warts |
Lactura basistriga (Fig. |
5 | Prominent, white to orange addorsal stripes with embedded orange warts; widespread across Midwest and southeastern US |
Lactura pupula (Figs |
– | No orange stripping or warts; broad, cinnamon-brown middorsum outwardly edged by black addorsal stripes; from west central Texas |
Lactura rubritegula (Fig. |
1 | Lateral lobe of juxta lightly sclerotized with 20–30+ spiniform setae; aedeagus with large, broadly concave aperture and thumb-like distal process | 2 |
– | Lateral lobe of juxta heavily sclerotized with 10–20+ thickened spiniform setae; aedeagus with obliquely concave aperture, thumb-like distal process absent | 3 |
2 | Uncus with strong medial constriction in basal third; broadly cylindrical to apex |
L. atrolinea (Fig. |
– | Uncus robust and tapering with slight medial constriction in basal third; narrowly cylindrical to apex |
L. pupula (Fig. |
3 | Uncus basally quadrangular |
L. subfervens (Fig. |
– | Uncus basally cordiform |
L. basistriga (Fig. |
1 | Anterior accessory pouch present on corpus bursae; 4–6 coils in ductus bursae; signa ca. half diameter of corpus bursa | 2 |
– | Anterior accessory pouch absent on corpus bursae; 6–12 coils in ductus bursae; signa ca. quarter diameter of corpus bursae | 3 |
2 | Diameter of ductus bursae coils subequal throughout; anterior accessory pouch connected to corpus bursae by broad opening |
L. atrolinea (Fig. |
– | Diameter of ductus bursae coils increasing in size anteriorly, anteriormost coil ca. 3× diameter that of posteriormost; anterior accessory pouch connected to corpus bursae by narrow opening |
L. basistriga (Fig. |
3 | Six to eight coils in ductus bursa |
L. rubritegula (Fig. |
– | Nine to twelve coils in ductus bursa |
L. subfervens (Fig. |
Eustixis pupula Hübner, [1831]: 24. Type locality: Georgia, USA. Type material: presumably lost
Eustixis leata Geyer, 1832: 5. Type locality: Unknown. Type material: not examined
Mieza igninix
Enaemia crassivenella
Enaemia crassinervella Slosson, 1896: 86; misspelling
Lactura pupula was first described as Eustixis pupula in vol. 3 of Hübner’s Zuträge zur Sammlung exotischer Schmetterlinge (1827–1831). The original description was published subsequent to Hübner’s death, and the approximate date of description has been inferred to be 1831 (
A few decades later
Enaemia crassivenella (Zeller, 1872) and Enaemia crassinervella (Slosson, 1896) are both synonyms of L. pupula—
Forewing pattern instantly distinguishes this species from its congeners. The most notable difference is the black streaking along the veins of the forewing, and two oblong antemedial spots and three oblong postmedial spots in the lower half of the forewing. The postmedial spots are arranged in a triangular pattern with the lower distal spot touching the inner margin. Female genitalia have 9–10 distal spirals in the ductus bursae. The larva's orange verrucae on white to orange addorsal stripes distinguishes it from all other Nearctic Lactura.
(Fig.
(Figs
Lactura pupula occurs in woodlands, thickets, scrublands, back dune and coastal strand communities, and along forest edges of central Texas northward in Midwest to Nebraska and Illinois, and eastward to South Carolina and the whole of Florida (Fig.
In central and west-central Texas, larvae show a reduction in the amount of dorsal orange maculation. A close relative of L. pupula, based on CO1 data in BOLD (BOLD: ACN5528), occurs in Tamaulipas, Mexico. It would be worthwhile to do more sampling in south Texas and northern Tamaulipas to better delineate the ranges of the two moths. Lactura pupula is rapidly expanding its range westward in Texas. In 2019, the first records of adults were made in Austin (Travis County), Boerne (Kendall County), and Camp Wood (Edwards County)—all at sites that have been regularly sampled over the past decade. Larvae were found in great numbers in the first two of these counties in April of this year.
Mieza subfervens
Lactura psammitis,
Lactura rhodocentra, Meyrick 1913: 142; syn. n. Type Locality: Texas, USA. Type material: not found at
Zeller described Enaemia psammitis from Texas in 1872. As early as 1874, Grote synonymized L. psammitis with L. subfervens; a decision followed subsequently by
Lactura rhodocentra (Mieza rhodocentra) was described from Texas by Meyrick in 1913. Shortly thereafter, it was designated as a synonym of L. basistriga by
Adult Lactura. 15 Lactura subfervens (heavy maculation), TX: Kaufman Co., Becker, 18 February 2011, J. McDermott coll., CO1 Barcode DLW-000111 16 Lactura subfervens (light maculation), TX: Harrison Co., Caddo Lake St. Pk., 14 June 1998, E. Knudson coll., CO1 Barcode DLW-000509 17 Lactura subfervens sapeloensis, FL: Marion Co., Hopkins Prairie (29.275N, 81.692W), 18 March 2013, J. Vargo coll 18 Lactura atrolinea, TX: Cameron Co., Sabal Palm Grove Sanctuary, 16–17 November 1998, E. Knudson coll., genitalia slide #TAM-2017-015, CO1 Barcode DLW-000510 19 Lactura rubritegula [HOLOTYPE], TX: Kendall Co., Boerne, D. Cain Home (29°52'51"N, 98°36'51"W), 27 April 2015, David Wagner & Delmar Cain colls., genitalia slide #TAM-2017-002, CO1 Barcode DLW-000816 20 Lactura basistriga, TX: Cameron Co., Sabal Palm Grove (25°51'9"N, 97°25'3.8"W), BBN15#27a, larva collected 25 April 2015, emerged 21 May 2015, Berry Nall coll., host: Sideroxylon celastrinum, genitalia slide #TAM-2017-005 21 Lactura nalli [PARATYPE], TX: Starr Co., Falcon Heights (26.5585N, 99.1220W), 19 March 2018, Berry Nall coll 22 Lactura pupula, FL: Nassau Co., Fort Clinch State Park, Ft. Clinch Fernandina Beach, DLW Lot: 2014D136, larva: 28 April 2014, emerged: 22 May 2014, host: Sideroxlon tenax, Richard Owen coll.
Male genitalia. 23 Lactura nalli [PARATYPE], TX: Starr Co., Falcon Heights (26.5337N, 99.1059W), larva: 30 March 2014, pupated: 05 May 2014, emerged: 06 November 2014, host: Sideroxylon celestrinum, Berry Nall coll., BBN14#06c, genitalia slide #TAM-2017-014, CO1 Barcode DLW-000486 24 Lactura subfervens sapeloensis [PARATYPE], GA: McIntosh Co., Sapelo Island, Lighthouse Rd. Salt marsh edge habitat (31°23'25.7"N, 81°16'55"W), 11–12 March 2016, James Adams and Brian Scholtens colls., genitalia slide #TAM-2017-018, Voucher Code TAM0010 25 Lactura atrolinea, TX: Cameron Co., Sabal Palm Grove Sanctuary, 16–17 November 1998, E. Knudson coll., genitalia slide #TAM-2017-015, CO1 Barcode DLW-000510 26 Lactura pupula, FL: Nassau Co., Fort Clinch St. Pk. Ferdinanda Beach, larva: 28 April 2014, emerged: 24 May 2014, host: Sideroxylon tenax, Richard Owen coll., DLW Lot: 2014D136, Genitalia slide #TAM-2017-016, CO1 Barcode DLW-000282, Voucher Code TAM0009 27 Lactura subfervens, TX: Uvalde Co., Neil’s Lodges, Rio Frio, larva: 17 April 2014, emerged: 16 April 2015, host: Sideroxylon lanuginosum, David L. Wagner coll., DLW Lot: 2014D45, genitalia slide #TAM-2017-019, Voucher Code TAM0007 28 Lactura basistriga, TX: Hidalgo Co., Bentsen St. Pk., 30 April 1995, E. Knudson coll., genitalia slide #TAM-2017-003, CO1 Barcode DLW-000513 29 Lactura rubritegula [PARATYPE], TX: Kendall Co., Boerne (29°52'51"N, 98°36'50"W), 27 April 2015, David Wagner and Delmar Cain colls., genitalia slide #TAM-2017-004 30 Lactura rubritegula [HOLOTYPE], TX: Kendall Co., Boerne, D. Cain Home (29°52'51N, 98°36'51"W), 27 April 2015, David Wagner & Delmar Cain colls., genitalia slide #TAM-2017-002, CO1 Barcode DLW-000816. Scale bar: 1mm. Dissections and images prepared by Tony Thomas.
Lactura subfervens adults can be immediately distinguished by the presence of scattered smoky red scales (although highly variable in density) over the forewing. The forewing lacks the basal subcostal red or black dash usually present in L. atrolinea, L. basistriga, and L. nalli. This species can also be separated from L. basistriga, L. nalli, and L. rubritegula by the absence of red scaling at the base of the patagium. Female genitalia differ from those of other Lactura in having 11 or 12 coils along the ductus bursae. The caterpillar is among the most distinct of the North America Lactura: it is the only species whose ground color is predominately white; seven pairs of pale stripes run the length of the body, giving the larva a frosted appearance. The darker stripes are due to the larva’s internal coloration showing through its transparent body wall; with the exception of the prothoracic shield, there is essentially no black pigmentation dorsally or laterally along the trunk.
(Figs
(Fig.
Lactura subfervens is found in woodlands, bottomlands, and thickets of central Texas northward to southeast Kansas, Missouri, and Illinois, and east through Gulf States to coastal Georgia (Fig.
For decades, less speckled forms of L. subfervens have been misidentified as L. basistriga in collections, literature (
Lactura subfervens collections from central and coastal Florida, and coastal Georgia show modest genetic differentiation (pairwise distance ~0.02) (Fig.
Male abdomens with scent-emitting androconial structures. 31 Lactura pupula, FL: Nassau Co., Fort Clinch St. Pk. Ferdinanda Beach, DLW Lot: 2014D136, larva: 28 April 2014, emerged: 24 May 2014, host: Sideroxylon tenax, Richard Owen coll., Genitalia slide # TAM-2017-016, CO1 Barcode DLW-000282, Voucher Code TAM0009 32 Lactura atrolinea, TX: Cameron Co., Sabal Palm Sanctuary (25°51'3"N, 97°25'1"W), ex-ova: female 25 November 2014, DLW Lot: 2014L121b, emerged: 17 February 2015, host: Sideroxylon celastrinum, genitalia slide #TAM-2017-006, Voucher Code TAM0008. 33 Lactura subfervens sapeloensis [PARATYPE], GA: McIntosh Co., Sapelo Island, Lighthouse Rd. salt marsh edge habitat (31°23'25.7"N, 81°16'55"W), 11–12 March 2016, James Adams and Brian Scholtens coll., genitalia slide #TAM-2017-018, Voucher Code TAM0010 34 Lactura nalli [PARATYPE], TX: Starr Co., Falcon Heights (26.5337N, 99.1059W), larva: 30 March 2014, pupated: 05 May 2014, emerged: 06 November 2014, host: Sideroxylon celastrinum, Berry Nall coll., BBN14#06c, genitalia slide #TAM-2017-014, CO1 Barcode DLW-000486 35 Lactura atrolinea, TX: Cameron Co., Audubon Sabal Palm Grove Sanctuary, 16–17 November 1998, E. Knudson coll., genitalia slide # TAM-2017-015, CO1 Barcode DLW-000510 36 Lactura subfervens sapeloensis, see 33 above. Dissections and images prepared by Tony Thomas.
Female genitalia. 37 Lactura basistriga, TX: Cameron Co., Sabal Palm Sanctuary (25°51'9"N, 97°25'3.8"W), larva: 25 April 2015, pupated: 29 April 2015, emerged: 21 May 2015, host: Sideroxylon celestrinum, Berry Nall coll., BBN15#27a, genitalia slide #TAM-2017-005, Voucher Code TAM0005 38 Lactura nalli [PARATYPE], TX: Starr Co., Falcon Heights (26.5337N, 99.1059W), genitalia slide #TAM-2017-013, CO1 Barcode DLW-000569 39 Lactura atrolinea, TX: Cameron Co., Sabal Palm Sanctuary (25°51'3"N, 97°25'1"W), 25 November 2014, David L. Wagner coll., genitalia slide #TAM-2017-007 40 Lactura pupula, FL: Duval Co., Little Talbot State Park, 24 March 2007, B.D. Williams coll., genitalia slide #TAM-2017-011 41 Lactura rubritegula [PARATYPE], TX: Kendall Co., Boerne (29°52'51"N, 98°36'51"W), 27 April 2015, David L. Wagner coll., ♀ DLW 2015D60.2b, genitalia slide #TAM-2017-001 42 Lactura subfervens, TX: Comal Co., New Braunfells off Huaco Sprgs, Loop Road, 24 March 1995, genitalia slide #TAM-2017-009 43 Lactura subfervens sapeloensis [PARATYPE], GA: McIntosh Co., Sapelo Island, Lighthouse Rd. salt marsh edge habitat (31°23'25.7"N, 81°16'55"W), 11–12 March 2016, James Adams and Brian Scholtens colls., genitalia slide #TAM-2017-017, CO1 Barcode DLW-000770, Voucher Code TAM0003. Scale bar: 2 mm. Dissections and images prepared by Tony Thomas.
Lactura subfervens sapeloensis is most easily identified by its Florida/Georgia distribution. We have not found consistent diagnostic characters that will distinguish it from L. subfervens in adult pattern or male genitalia. Female genitalia do show modest differentiation: there are 12 or13 coils in the ductus bursae of L. subfervens and nine or ten coils in our preparations of L. subfervens sapeloensis.
We derived this trinomen from Sapelo Island, Georgia, where the moth is particularly common, and from which most of the paratype series was collected.
Lactura subfervens sapeloensis is found in coastal strand communities, mesic woodlands, thickets, flatwoods, scrublands, and edges of wetlands from central Florida, north into southeast Georgia (Fig.
Holotype male, dry pinned, GA: McIntosh Co., Sapelo Island, Lighthouse Rd., salt marsh edge habitat (31°23'25.7"N, 81°16'55"W), 11–12 March 2016, light trap, James Adams & Brian Scholtens coll., genitalia slide #TAM–2017– 017, CO1 Barcode DLW–000570, Voucher Code TAM0003, Deposited at
Mieza atrolinea
Barnes and McDunnough, 1913: 142. Type locality: San Benito, Texas, USA. Type material:
Lactura atrolinea is easily distinguished by its larger size and nearly continuous series of black antemedial and postmedial spots. The tegula is black apically as are the spots over the thorax; the forewing has a thin black subcostal dash. In females the ductus bursae has five or six coils anteriorly. The larva displays attractive, metallic blue, dorsal warts that unmistakably separate this species from its co-occurring Texas congeners.
Geographic distribution of Lactura north of Mexico. Single dots may represent >1 individuals. 52 Lactura pupula (n = 231), Lactura basistriga (n = 93), Lactura rubritegula (n = 13), and Lactura nalli (n = 11) 53 Lactura subfervens (n = 472), Lactura atrolinea (n = 138), and Lactura subfervens sapeloensis (n = 20).
(Fig.
(Fig.
Lactura atrolinea inhabits the mesic woodlands, coastal scrub, and palm forests of south Texas, southward into Mexico. Breeding populations are known from coastal areas of Texas from Fort Bend to Cameron counties (Fig.
Mieza basistriga
Barnes and McDunnough, 1913: 142. Type locality: San Benito, Texas, USA. Type material:
Lactura basistriga can be distinguished from L. rubritegula by the absence of dorsal red scales on the tegula. Most forms exhibit a basal, red, subcostal dash on the forewing, and all individuals lack the scattered flecking of red or brown scales characteristic of L. subfervens. Many, but not all individuals can be distinguished from L. rubritegula by a reduced upper postmedial spot and the convex arcing of the three lower postmedial spots, due to a more basal placement on the lowermost spot. Adults are exceedingly close to and often indistinguishable from those of L. nalli; see comments under that species. With the exception of L. nalli and L. atrolinea, female genitalia differ from other Lactura in having four or five coils in ductus bursae. Larvae with a dark dorsum that ranges from smoky gray-green to nearly black, and without the metallic blue dorsal pinacula of L. atrolinea; larvae of L. nalli are lime green above and lack any hint of white striping or black fill between the subdorsal stripes that are present in L. basistriga.
Phenology of North American Lactura, (blue square) all specimen records, (green square) records representing a unique collecting event (multiple individuals from the same collecting event represent a single data point). 54 L. pupula from Florida/Georgia (n = 82) 55 L. pupula from Texas (n = 74) 56 L. pupula from Midwest, U.S. (n = 54) 57 L. atrolinea (n = 138) 58 L. subfervens (n = 474) 59 L. subfervens sapeloensis (n = 21).
Phenology of North American Lactura, (blue square) all specimen records, (green square) records representing a unique collecting event (multiple individuals from the same collecting event represent a single data point). 60 L. nalli (n = 29) 61 L. basistriga (n = 87) 62 L. rubritegula (n = 13).
(Fig.
(Fig.
Lactura basistriga inhabits the woodlands, thickets, palm forests, and scrublands of the lower Rio Grande Valley; presumably the core of its range is in Mexico. Breeding populations are known from the extreme southern Texas counties of Hidalgo and Cameron (Fig.
Lactura rubritegula
Matson & Wagner, 2017: 141. Type locality: Kendall Co., Texas, USA. Type material:
Lactura rubritegula can be distinguished from its relative L. basistriga by the prominence of red dorsal scales on the tegula. It lacks the red subcostal dash that can be found in most forms of L. basistriga and L. nalli, and the scattered flecking of red or brown scales characteristic of L. subfervens. Many, but not all, individuals can be distinguished by the basal displacement of the lowermost antemedial spot, somewhat enlarged upper postmedial spot, and the concave arc (open to termen) of the three lower postmedial spots. Female genitalia differ from other Lactura in this treatment in having six or seven coils in the ductus bursae. Unique to the larva of this species is the rusty brown dorsum.
(Figs
(Fig.
Lactura rubritegula is known from the Hill Country around San Antonio, Texas, westward to Edwards and Uvalde counties, but its range remains unclarified due to previous taxonomic confusion with L. basistriga and other Lactura (Fig.
A comparative assessment of L. rubritegula relative to L. basistriga is provided in
Adult Lactura nalli are similar to L. basistriga, and in some cases indistinguishable. The following generalizations can be made when comparing series of adults: when the red basal streak is present, it is almost always shorter, usually ending before the most basal antemedial spot; the antemedial wing spots tend to be more reduced; and the hindwings are more roseate and given to pink, while those of L. basistriga are more orange-red in hue. L. nalli can be distinguished from L. rubritegula by the absence of red tegular scales (that are visible in dorsal view). Like L. basistriga, many individuals can be differentiated from L. rubritegula by a reduced upper postmedial spot and the convex arc facing the termen of the three lower postmedial spots. L. nalli can be separated from L. subfervens by the absence of the scattered flecking of red or brown scales over the forewing. Female genitalia overlap with L. basistriga but differ from other Lactura in having 4–5 anterior whirls present in the spiraled ductus bursae. Larvae can be immediately distinguished from those of other North American Lactura by their green semitransparent dorsum lacking any black or white markings, which is in stark contrast to the dark dorsum of L. basistriga.
(Figs
(Figs
Holotype male, dry pinned, TX: Starr Co., Falcon Heights (26.5585N, 99.1220W), 05 March 2018, Berry Nall coll., Deposited at
Adults. TX: Starr Co., Falcon Heights (26.5585N, 99.1220W), 27 February 2018, Berry Nall coll. (1♂); TX: Starr Co., Falcon Heights (26.5585N, 99.1220W), 06 March 2018, Berry Nall coll., BBN18#07 (1♂) Larvae. TX: Starr Co., Falcon Heights (26.5337N, 99.1059W), ex-ova from female 25 February 2018 – 6 March 2018, BBN18#01, BBN18#05, BBN18#06, BBN18#07, Berry Nall coll., (n~60) (
We name this new species after our colleague Berry Nall who provided the majority of type material, reared four clutches of larvae, and first photographed the larva.
So far as known, L. nalli and L. basistriga are allopatric in south Texas, with L. basistriga being limited to Tamualipan communities of the lower eastern Rio Grande Valley, and L. nalli restricted to the Chihuahuan scrub areas of the western end of the Valley (Fig.
Our phylogenetic analyses of a multi-gene dataset based on seven genes (Fig.
Lactura has challenged some of North America’s top systematic microlepidopterists, including August Busck, Harrison Dyar, and Ronald Hodges. Our contributions to the biosystematics of this group were kick-started by larval material and CO1 data for initial sorting. Both data sources were quintessentially important for L. nalli, for which no definitive adult characters are yet known. The nuclear data presented here were the last data to be added, and thus acted as a corroboratory data source, affirming the taxonomic decisions that we made based on larvae, life history information, CO1 data, genitalic characters, and distributional data.
As the taxonomic understanding of this group is untangled, it is likely that North American members of Lactura will be relegated to a new or different genus. The type-species Lactura dives (Walker, 1854) is a striking orange and black Australian moth with greater than ten percent (uncorrected) barcode dissimilarity from North American members of the genus. Presently, more than 80 species of Lactura are distributed worldwide and include an array of seemingly unrelated phenotypes (
All known species of North American Lactura are specialists on the host-plant genus Sideroxylon (Sapotaceae). L. pupula, L. rubritegula, and L. subfervens occur in sympatry in central Texas where they use Sideroxylon lanuginosum. We have found caterpillars of L. pupula and L. subfervens feeding alongside one another on early spring foliage; L. rubritegula occurs later, flying only at the tail-end of the flights of its congeners (
CO1 data were valuable in unmasking misidentifications, disambiguating cryptic lineages, and helping guide our fieldwork and genitalic dissections. Given our new understanding of this genus, the records in Barcodes of Life Database (BOLD) were in dire need of curation due to the confusion of L. subfervens and its phenotypic overlap with L. basistriga and L. rubritegula; as well as its failure to treat L. psammitis and L. rhodocentra as synonyms. Forty-six percent of the 116 North American Lactura specimens in BOLD were misidentified prior to the submission of
Evolution advances at different rates across the various behavioral, ecological, molecular, and morphological axes used to adjudicate taxonomic decisions (e.g., adult color/pattern, male and female genitalia, larval morphology, DNA, courtship behaviors, etc.). This revision of North American Lactura is a case in point that speaks to the value of larvae, life history data, and molecular analyses over the set of salient adult characters commonly used by moth systematists. Given the overlapping and seemingly indistinguishable adult phenotypes and male genitalic structures in Lactura, our findings serve as an endorsement of the value that larvae and molecular data hold for some lepidopteran groups. We venture that larval phenotypic and life history data will prove equally valuable in advancing our systematic understanding of the rich lacturid faunas of Mexico and the Neotropics.
We would like to thank the Biodiversity Institute of Ontario, University of Guelph, for providing DNA barcoding support through the iBOL project, funded by Genome Canada and others, as well as the National Museum of Natural History, Smithsonian Institution, for their generous contributions of genetic data. Specimen loans were provided by the late Edward C Knudson (Texas Lepidoptera Survey), James R McDermott, Richard L Brown (Mississippi Entomological Museum), and Jim Vargo. Andy Deans (Frost Entomological Museum) and Gregory Zolnerowich (KSU Museum of Entomological and Prairie Arthropod Research) provided specimen records from their respective institutions. A special thanks to Delmar Cain who helped with many aspects of this effort: collecting specimens and providing phenological data for the three species of Lactura on his property, egging females for ex-ova rearings, assistance with rearing, sending photographs of adults and larvae, providing lodging, and much encouragement. We are much indebted to Berry Nall for his exceptional rearing and photographic assistance and for collecting most of the type series; it was through his efforts that we could describe L. nalli as new. Ann Hendrickson sent photographs and collected specimens of Lactura from her ranch in Camp Wood, Texas. We thank Brian Scholtens and James Adams for sending material from Sapelo Island, GA, and Lance Durden and Rachel Guy for assisting TAM while on Sapelo Island. Jimmy Paz and Seth Patterson assisted with visits to the Sabal Palm Sanctuary in Brownsville. We are especially grateful to Tony Thomas who prepared most of the genitalic preparations and the (stacked) photographs used in this work (Figs
Table of localities
Data type: occurrence