Corresponding author: Paul Z. Goldstein ( email@example.com )
Academic editor: Donald Lafontaine
© 2017 Paul Z. Goldstein, Michael W. Nelson.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation: Goldstein PZ, Nelson MW (2017) Two psammophilic noctuids newly associated with beach plum, Prunus maritima (Rosaceae): The Dune Noctuid (Sympistis riparia) and Coastal Heathland Cutworm (Abagrotis benjamini) in Northeastern North America (Lepidoptera, Noctuidae). ZooKeys 661: 61-89. https://doi.org/10.3897/zookeys.661.10867
Beach plum, Prunus maritima Marshall, 1785 not Wangenh., 1787 (Rosaceae), currently under development as a potential crop, represents an under-acknowledged host plant for several Lepidoptera that have undergone declines in the northeastern USA. The Coastal Heathland Cutworm, Abagrotis nefascia (Smith, 1908), and the Dune Noctuid, Sympistis riparia (Morrison, 1875), are unrelated species of psammophilic noctuines (Lepidoptera: Noctuidae) regularly encountered on a localized basis in coastal southern New England and New York, and whose precise life history requirements are undocumented. We inferred and, based on field observation and rearing, corroborated beach plum as a larval host for these species in Massachusetts; the plant’s role in sustaining other moths with limited or contracting regional distributions is discussed. Sympistis riparia, belonging to a widely distributed complex of closely related species, has been associated specifically with both maritime and freshwater dunes. The eastern populations of Abagrotis nefascia represent a conspicuous range disjunction, separated from the nearest western populations by more than 2000 miles, and originally described by Franclemont as race benjamini of A. crumbi, both later synonymized with A. nefascia. Following examination of types and other material, an evaluation of putatively diagnostic features from both the original description and our own observations, genitalic characters, and the results of provisional barcode analyses, Abagrotis benjamini Franclemont, stat. rev., is elevated to the rank of a valid species rather than representing eastern populations of Abagrotis nefascia (=crumbi) to which it originally referred.
Abagrotis, Sympistis, beach plum, Prunus maritima, Noctuidae, psammophile
Distributions of herbivorous insects are often constrained by ecological or edaphic factors, in addition to the presence of their host plants. In northeastern North America, some of the most threatened terrestrial plant communities, including pitch pine-scrub oak barrens, maritime heathlands, shrublands, and grasslands, are limited to sandy, well-drained soils geologically derived from glacial outwash or ancient lake beds, sometimes collectively referred to as sandplains. Lepidoptera associated with such soils are often localized and hence prominent among those considered regionally endemic or locally threatened, and in the Northeast are heavily concentrated in coastal areas. Habitat associations and life history requirements of many sandplain insects remain undocumented, potentially due to a combination of regional variation in host specificity and the fact that observations of adult moths may belie the precise location of their larval hosts. Dunes and related habitats, such as barrier beaches, are obvious features of coastal areas, often adjacent to strictly terrestrial sandplain habitats, but are commonly overlooked as potential resources for invertebrates and may further confound our inferences of host associations. In several cases, moths’ habitat associations, if not host plants themselves, have been inferred or asserted in the absence of corroborating life history information, even to the point of being reflected in the animals’ common names.
The Dune Noctuid, Sympistis riparia (Morrison), and the Coastal Heathland Cutworm, Abagrotis nefascia (Smith), are cases in point. Both represent large noctuid genera with numerous cryptic species (
The range of S. riparia extends westward to California and British Columbia, and although the eastern portion includes sporadic inland occurrences and coastal areas from New Brunswick to the mid-Atlantic, records are most heavily concentrated along the southern New England coast and the southern shores of the Great Lakes. The distribution of Abagrotis nefascia, in contrast, is more conspicuously centered in western North America, where it is considered a major pest of grapes (
This project began with the modest goal of elucidating the life history and host plant of S. riparia, which we all-too-slowly grew to suspect included one of the most common dune shrubs, beach plum (Prunus maritima). Well-known regionally for its fruit, this shrub has a checkered history of cultivation (
Despite its well-known association with both maritime and inland dunes, the host(s) of S. riparia have eluded lepidopterists for decades. Among the candidate host plants suggested on the basis of their prevalence in dunes was American beachgrass (Ammophila breviligulata Fern.), which would account for a high concentration of records along the Atlantic Coast as well as the shores of the Great Lakes. Beachgrass represents not only an important structural and stabilizing component of dunes but an important host for herbivorous insect biodiversity, including other noctuid dune associates such as Apamea lintneri (Grote, 1873) (
With this in mind, we began our survey of potential host plants with what we surmised to be more likely candidates, the shadbushes or serviceberries Amelanchier Medikus. Amelanchier was also among the hosts recorded by
As a state-listed species, observations of S. riparia are tracked by the Massachusetts Natural Heritage Program, and upon examining these data we initiated our survey at a series of sites near Moshup Trail in Aquinnah, Massachusetts (Figs
Section of coastal southern New England including Cape Cod and the Massachusetts offshore islands. Study sites in Aquinnah and Dartmouth marked with a ★.
Martha’s Vineyard and neighboring islands comprising Dukes County with indication of town boundary lines and relevant geologic formations and substrates overlain. Moshup Trail and Lobsterville Dunes sites marked with a ★.
a Distribution of Sympistis riparia adults recorded from Massachusetts as of 2016 (MNHESP), b Distribution of Sympistis riparia adults recorded from Martha's Vineyard as of 2016 (MNHESP).
a Distribution of Abagrotis benjamini adults recorded from Massachusetts as of 2016 (MNHESP), b Distribution of Abagrotis benjamini adults recorded from Martha’s Vineyard as of 2016 (MNHESP).
A casual survey for Sympistis larvae on Amelanchier in April 2011 was timed to coincide with the plant’s flowering season, but was unsuccessful. Later the same season, however, light trapping efforts at a site approximately three kilometers distant yielded adult moths in high numbers which were unprecedented in our experience. Although radically different from our initial target site in terms of its immediate plant community composition, which includes a mixture of mesic forest and morainal scrub, the trap site overlooks the expansive and under-studied peninsular dune system, Lobsterville Dunes. This site supports a structurally and floristically diverse vegetative cover lichenized and dominated by beach plum Prunus maritima, scrub oak Quercus ilicifolia Wangenh., and beach heather, Hudsonia tomentosa Nutt. (Fig.
Examples of habitats represented at the Lobsterville Dunes. a Immediate backdune, dominated by beach plum, also in foreground b Floristic diversity on a secondary dune, the vegetation including beach heather (Hudsonia tomentosa) and heavy lichenization c A section of dune supporting a mixture of salt- and wind-dwarfed oak, including scrub oak (Quercus ilicifolia) in the foreground.
Pinned specimens were examined with an incandescent light source. Genitalic preparations varied, the more recent ones following parts of
Even a cursory examination of the known distribution of Abagrotis nefascia reveals an obvious disjunction between the range occupied by nefascia west of the Rocky Mountains and the populations restricted to a narrow band along the northeastern coast of North America. Recognizing this,
Those populations formerly known as A. crumbi race benjamini have thus not been validly recognized as taxonomically distinct since 1998. Despite the formal synonymy, benjamini has been retained as a subspecies of A. nefascia outside the taxonomic literature, most prominently in the roster of protected species and subspecies in New York (New York Natural Heritage Program 2016), and Connecticut (Connecticut Dept. of Energy & Environmental Protection 2016) as Abagrotis nefascia benjamini, as well as at iNaturalist.org. This usage appears traceable to entries in NatureServe (http://explorer.natureserve.org/), a portal for disseminating information on taxa of conservation concern. Below we revisit the grounds for retaining or elevating the status of A. benjamini based on available character information, and revise its status accordingly, providing a diagnosis and re-description of the genitalia. A more detailed treatment of the larvae and life history of these animals will occupy a separate work.
Franclemont wrote in his description of race benjamini (1955: 46): “Similar to the typical race, but the markings are a little less distinct, and the color is generally duller. All the specimens are a rather uniform tannish brown with a contrasting purplish gray terminal area.” He described the male genitalia as “somewhat larger than the typical race” and the female as having the “ductus bursae more heavily sclerotized; general characteristics similar to those of forbesi.” The paratypes of benjamini comprise specimens from East New York [Brooklyn], NY; Connecticut; and Martha’s Vineyard, MA. Upon close examination of these and other specimens, including a series of Massachusetts specimens and the holotypes of A. crumbi, A. nefascia, A. forbesi, and A. reedi, we noticed consistent, if subtle, differences between eastern specimens and typical A. nefascia. In addition to those differences in coloration noted in
As Lafontaine suggested, subtle features of wing pattern may be unreliable indicators of phylogenetic affinity in Abagrotis. That said, both Franclemont and Lafontaine acknowledged trends in coloration and shading among eastern A. nefascia that may serve to differentiate most specimens from their western counterparts. Eastern specimens range in forewing ground color from a gray brown to brick red; we have not seen any with a dark-maroon forewing ground color.
In addition to exhibiting the secondary diverticulum putatively diagnostic for A. nefascia (Lafontaine, 1998: 221), the scobinate plate on the vesicae of eastern specimens tends to be less evenly denticled. The basal sclerotized patch consists of a more heteroideous series of teeth, with two or three very prominent and 5–8 much smaller (Figs
Finally, we observe that the presence of signa on the female bursa has been interpreted inconsistently in this group.
Interspecific variation in COI sequences in Abagrotis is atypically low for a noctuid genus. In the analyses of
We typically eschew the use of distance-based analyses of character data as rigorous arbiters of either phylogenetic relationship or species diagnosis (
In Aquinnah, high numbers of adult S. riparia were observed, routinely exceeding 200 specimens in a single light trap, the highest numbers appearing between 21 June and 5 July. Based on our capture dates, the flight season of S. riparia is somewhat protracted, extending from mid-June through early August. Females retained for obtaining eggs oviposited with varying success, most readily when presented with honey water and in the presence of beach plum foliage. Eggs proved difficult to overwinter without succumbing to desiccation or mold but efforts involving chilled hydration and aureomycin-laden artificial diet are ongoing.
Other species appearing in unusually high numbers included A. benjamini, the erebids Argyrostrotis anilis (Drury, 1773), Catocala herodias Strecker, 1876, and Drasteria graphica Hübner, 1818; and the noctuids Schinia spinosae (Guenée, 1852) and Eucoptocnemis fimbriaris (Guenée, 1852). Species apparently associated with beach plum included regular occurrences of Wild Cherry Sphinx (Sphinx drupiferarum J.E. Smith, 1797), which has declined in the Northeast (Wagner, 2012), and now appears confined to coastal areas (
Finally, we collected at least four species of Abagrotis in addition to A. benjamini, namely A. alternata, A. brunneipennis (Grote, 1875), A. cupida (Grote, 1865), and A. magnicupida Lafontaine, 1998, some of which have since been reared as wild-caught larvae from beach plum. Abagrotis benjamini adults first appeared in late June, apparently aestivating and appearing in highest numbers later in the season, primarily in August but extending through September.
Initial efforts to locate larvae on beach plum at Aquinnah in 2012 and 2013 were less immediately successful due to a combination of seasonal conditions and timing. Larvae of Sympistis riparia were collected from beach plum and reared to adults at a mainland site in Dartmouth, MA on 16 and 22 May 2013 (Fig.
a–d Larvae of Abagrotis benjamini a–c in situ, Aquinnah, MA, 2016 (P. Goldstein) d Dartmouth, MA, 2012. (M. Nelson).
Larvae of both Abagrotis benjamini and Sympistis riparia are subterranean by day, and we were impressed in particular by the ease with which S. riparia larvae move through sand. As has been observed of other Sympistis, larvae of S. riparia construct an underground cell within which to pupate. With S. riparia, the cell is approximately 3 cm below the surface of the sand, and lined with a thin layer of silk. For this reason, the precise time of pupation was difficult to pinpoint. But, based on our extraction of some larvae and, in the case of Abagrotis, their successful pupation in paper towels, the pupal period for S. riparia was under 20 days; that of A. benjamini was somewhat longer, between 25 and 33 days.
The maturity of the S. riparia caterpillars at the time of their observation in the field was surprising given the brief time their host had been in flower (no more than 10 days). Some Sympistis (e.g., S. forbesi Zacharczenko & Wagner, 2014, S. piffardi (Walker, 1862)) are known to over-winter as eggs (
Our observations of mature Abagrotis larvae, on the other hand, are consistent with those of
Damage from storm surge at Lobsterville Dunes following Hurricane Sandy, October 31, 2012 (A.O. Fisher).
The following abbreviations refer to collections from which specimen material forms the basis of this work:
Beyond the history of nomenclatural confusion surrounding Abagrotis nefascia and its synonyms, complicating matters further is the difficulty in locating type material, some of which is incompletely labeled or lost, including the genitalic preparation of the benjamini holotype. Notwithstanding the apparently mixed type series of A. nefascia (
Meanwhile, Benjamin’s dissection (FHB 850), which represents the holotype slide of A. crumbi as per
However, most of Franclemont’s paratype material for A. crumbi (24 of 27 specimens) and A. benjamini (5 of 8 specimens) is intact, as are series of adults and accompanying dissections of Massachusetts Abagrotis “nefascia” collected by Jones and Kimball on Martha’s Vineyard and Nantucket, the dissections made subsequently by A.E. Brower.
Abagrotis nefascia. (Figs
Lectotype of Rhynchagrotis nefascia Smith. a Dorsal b Ventral. Scale bars: 1 cm (Photos C. Richenbacher).
Abagrotis crumbi. (Figs
Abagrotis reedi. Holotype (♂,
Abagrotis forbesi. Holotype (♂,
Other material examined.
Abagrotis nefascia. USA: COLORADO (2♀): Oak Creek Cany Col VII.12; Col. Jacob Doll.;
Holotype of Abagrotis crumbi Franclemont (=nefascia). a Dorsal b Ventral Scale bars: 1 cm (Photos B. Proshek).
Abagrotis nefascia (Smith), Yakima, WA. P. Landoldt. a Dorsal b Ventral. Scale bars: 1 cm (Photos B. Proshek).
Abagrotis magnicupida. USA: MASSACHUSETTS (2♂, 2♀): West Tisbury, Manuel F. Correllus State Forest, Willow Tree Bottom, 20 July 2004; P.Z. Goldstein leg. (1♂, 3♀);
Abagrotis brunneipennis. USA: MASSACHUSETTS: Edgartown, Manuel F. Correllus State Forest, bathtup deerstand 41°23.770'N, 70°35.550'W, 30 June 2011 @ UV trap P.Z. Goldstein (1♂).
Abagrotis alternata. USA: MASSSACHUSETTS (1♂, 2♀): West Tisbury, Manuel F. Correllus State Forest, Willow Tree Bottom 22 August 2000 (1♂, 1♀);
Type material (Abagrotis crumbi benjamini Franclemont, 1955)
Holotype of Abagrotis crumbi race benjamini Franclemont. a Dorsal b Ventral. Scale bars: 1 cm (Photos B. Proshek).
Slide labels [Paratypes]: (Fig.
(not including ~13 with DNA barcodes pending)
MASSACHUSETTS (28♂, 18♀): Edgartown (1♂, 2♀): Katama Plain 41°21.472'N, 70°31.256'W, 19 June 2010 (1♂); Wintucket Cove frost bottom 24 July 1991 (1♀); Felix Neck Wildlife Sanctuary 7 VII 1989 P.Z. Goldstein, leg. (1♀). Aquinnah (22♂, 15♀): East Pasture Road, 41°20.494'N, 70°47.248'W, @ UV Trap: 30 June 2013 (1♂, 1♀); 1 July 2011 (1♂); 15 July 2011 (1♂); off Moshup Trail/E. of Moshup Trail, 41.324894, -70.810698 / 41°19'29.6'N, 70°48'38.5'W (7♂, 7♀): 17 vii 2003 (3♂, 1♀) [
Forewing ground color ranging from pale gray brown to, more commonly, a rusty brown, occasionally reddish brown (paprika colored), never dark; both FW and soma more heavily peppered with black scales than in A. nefascia; both fasciae and subterminal line (as dashes on underside, scalloping on upperside) less conspicuous than in A. nefascia. Scobinate patch on vesicae of male genitalia with 12 or fewer denticles, at least two of them markedly larger than others. Female bursa with a single signum.
Abagrotis benjamini Franclemont, Dartmouth, MA. M.W. Nelson. a Dorsal b Ventral. Scale bars: 1 cm (Photos B. Proshek).
Everted vesica of A. nefascia, Yakima, WA.
Genitalia of Abagrotis crumbi (=nefascia). a Holotype, ♂.
Genitalia of Abagrotis crumbi benjamini (Paratype).
Everted vesica of Abagrotis benjamini, Aquinnah, MA. a
This work began as a seemingly challenging attempt to sleuth out what turned out to be an obvious host plant, but led us to understand better the life histories and in one case the taxonomy of two apparently psammophilic species, and to explore an interesting dune fauna that complements conventional understanding of sandplain moths. Abagrotis benjamini is endemic to a narrow coastal area of northeastern North America. Long assumed to be an oligophagous species associated with a range of rosaceous and ericaceous plants, A. benjamini is here associated specifically with beach plum Prunus maritima for the first time based on reared wild caught larvae, observed feeding primarily on flowers. Although the distribution of beach plum in combination with known records of A. benjamini and documented high abundance of the moth in dunes dominated by P. maritima strongly suggests its role as an important host, co-occurring rosaceous plants, in particular Amelanchier cannot be ruled out as alternative hosts. The reinstatement of A. benjamini follows a mildly tortuous history of nomenclatural confusion disentangled by
The association of Sympistis riparia with dunes was well documented and accurate; that of A. nefascia with coastal heathlands less so. Our elucidation of beach plum as a host was hampered by the fact that each of these moths had been recorded from sites apparently lacking this plant, and possibly by the facultative use of other hosts, especially in the case of A. benjamini. We were also misled by the fact that our initial target sites at Moshup Trail, while adjacent to considerable dune habitat, were more conspicuously unique for other reasons. The possibility that the unique habitat in the immediate vicinity of our trapping records had little to do with the high numbers of Sympistis riparia did not at first occur to us, particularly since beach plum was not especially dominant; in fact, the heathlands at the site were consistent with what we thought we knew about Abagrotis benjamini.
In light of a growing body of literature devoted to desert biodiversity, including that of moths (e.g.,
We are especially grateful to Albert O. Fisher and Brendan O’Neill for access to sites at Moshup Trail, and to Bret Stearns and the Wampanoag Tribe of Aquinnah (Gay Head) for permission to work at Lobsterville. Clara Athearn, Sharon Briton, Kendra Buresch, Oona Carroll, Luanne Johnson, Noah Manning, John Patrick, Matt Pelikan, Estelle Perera, and Tim Simmons assisted in collecting larvae. Ben Proshek (SEL) prepared dissections and generated images; Lucrecia Rodriguez (SEL) generated images. Gary Ouellette (USDA-ARS) generated templates for several maps, and Mark Metz helped construct the final versions.. The staff at Massachusetts Natural Heritage & Endangered Species Program (MNHESP) gave permission to use distribution maps of S. riparia and A. benjamini. David Grimaldi and Courtney Richenbacher (