Epimartyria pardella (Walsingham)

Davis, Donald R. & Landry, Jean-Francois, 2012, A review of the North American genus Epimartyria (Lepidoptera, Micropterigidae) with a discussion of the larval plastron, ZooKeys 183, pp. 37-83 : 58-62

Epimartyria pardella (Walsingham) Figs 3813 –173288– 96.

Micropteryx pardella Walsingham 1880: 83.

Epimartyria pardella (Walsingham) 1898: 161.- Kearfott in Smith 1903: 125.- Dyar 1903: 581.- Meyrick 1912: 6.- McDunnough 1939: 110.- Davis 1983: 5; 1984: 341.- Kristensen 1984b: 97.- Tuskes and Smith 1984: 40.- Nye and Fletcher 1991: 113.- Poole 1996: 716.- Hashimoto 2006: 43.- Powell and Opler 2009: 33.

Diagnosis:

Adults of Epimartyria pardella most resemble those of Epimartyria bimaculella in possessing dark fuscous forewings marked by pale golden spots. Four spots are present on the forewing of pardella with two of these located across the distal third of the wing. In contrast, a total of two yellowish spots occur in bimaculella, with only a single large costal spot present beyond the middle of the forewing. In the male genitalia, the caudal lobes of sternum X (uncus) are more simple than those of the other members of Epimartyria in consisting of more shallow, rounded lobes compared to being curved and more slender in the males of auricrinella and bimaculella.

Adult

(Figs 3, 8). Head: Vestiture light orange brown. Antenna with vestiture of scape and pedicel concolorous with head; scales of flagellum pale golden yellow. Labial palpus pale brown to cream.

Thorax: Dark fuscous with coppery to purplish luster. Tegula concolorous with head. Forewing dark fuscous with coppery to purplish luster dorsally, marked with four, pale yellowish spots; the largest, irregularly rectangular and slightly oblique spot extends from costa approximately halfway across the distal third of wing; a smaller, more oval spot opposite costal spot on dorsal margin; an oblique basal spot arising midway along dorsal margin and extending halfway across wing to base of radial vein; a fourth, smallest spot at base of wing; forewing less iridescent ventrally; fringe pale yellow along termen, more gray along dorsal margin. Forewing length: 5.0-5.5 mm. Hindwing mostly gray, becoming darker and slightly iridescent toward apex; fringe gray; fringe light to dark gray. Legs medium to dark brown dorsally, paler brown ventrally and over tarsomeres; epiphysis present, ~ 1/3 the length of foretibia and arising slightly beyond its midlength.

Abdomen: Piliform scales light to dark brown.

Male genitalia (Figs 88-92): Tergum X with more slender caudal lobes. Caudal apex of sternum X (gnathos) not deeply divided, with short, triangular caudal lobes and without accessory lateral lobes. Valva short, ventral length less than 1/3 the maximum midventral length of segment IX; apex rounded and bearing a short, stout subapical spine; mesal surface smooth, without median process; elongate basal process nearly equal to length of valva. Dorsal branch of phallus more depressed, with subapical margins bearing short, paired spines, gonopore with less thickened radial folds than in previous two species.

Female genitalia: (Figs 93-96): As described for genus. Caudal end of genital sclerite deeply furcated; length of furcations exceeding length of short, undivided base.

Egg. White; dimensions 0.44 × 0.44 mm. Tuskes and Smith (1984) report the ova are flattened, circular and smooth when first deposited but soon become spherical and covered with numerous minute projections similar to those reported for Micropterix calthella (L.) by Lorenz (1961). The eggs were observed to hatch in 21 days at 22°C.

Larva. Not examined. The following description has been summarized from Tuskes and Smith (1984): Body length 4.3 to 4.6 mm; width 1.4 mm; height 1.2 mm. The body tapering at both ends with highest and broadest point at abdominal segment 4. Dorsal and lateral surface brown to dark brown, ventral surface light brown.

Head. Length 0.5 mm, diameter 0.27 mm. Brown. Antennae prominent, 3-segmented and situated on small tubercles located on dorsal lateral portion of head. Stemmata with 5 facets and located near base of antenna. Labrum simple with a pair of 3-segmented palpi. Mandibles simple and dark brown. Head diameter of first and second instar larvae 0.11 and 0.22 mm, respectively.

Thorax: Prothorax distinctly narrower than mesothorax. Prothoracic shield with 10 peg-like setae, 8 on the anterior and lateral border and 2 dorsally. Mesothorax with 8 setae, 6 on dorsal and lateral anterior portion of gray brown pigmented area, and 2 just ventral to this pigmented area. Setae of metathoracic segment similar to those of mesothorax except subdorsal (D2) seta is greatly reduced in size. All thoracic segments have additional small micro-seta just dorsal to each true leg. Thoracic legs brown, with 3 segments (excluding coxa) and simple claw.

Abdomen: Abdominal segments Al to A8 (and T2 and T3) with serrated knobs which form a dorsal and lateral ridge; areas between ridges concave. The mid-dorsal area concave with a small dark depression present on posterior of segments T2 to A8. Segments Al to A8 each with one dorsal seta (length 0.18 mm) atop dorsal ridge. Segments Al to A8 with reduced, almost microscopic subdorsal (D2) seta (length 0.04 mm) and prominent lateral seta (length 0.12 mm) on lateral ridge. Dorsal. subdorsal and lateral setae occur in brownish pigmented area which has rough and wrinkled appearance. Dorsal and lateral intersegmental area constricted and may contain series of 8 to 20 microscopic dots. Cuticle ventral to lateral ridge smooth and light brown. Series of brown dots form pattern around protuberance that usually support a small seta. Conical ventral prolegs occur on segments Al to A8, with a small, sclerotized protuberance present on ventral surface of each. Segments A9 and Al0 fused and with enlarged simple sucker. Spiracles posterior and ventral to lateral setae.

Larval hosts.

Hepaticophyta : Conocephalaceae : Conocephalum conicum (L.) Dumort.; Pelliaceae : Pellia species, with the latter host preferred from rearings ( Tuskes and Smith 1984).

Pupa.

Not examined. Exarate, decticous; white to light brown.

Cocoon.

Not examined. Brown, oval in general form, measuring 5.5 × 4.5 mm; primarily of silk with small fragments of vegetation attached.

Biology

(Fig. 8). Tuskes and Smith (1984) observed the eggs of Epimartyria pardella to be deposited in June on the underside of liverwort thalli singly or in small clusters of up to five eggs. They are white, measuring ~ 0.40 × 0.44 mm, and are flattened, circular, and smooth when first deposited but become spherical within a short time and covered with a series of small projections. First instar larvae ~ 0.75 mm long were reported to emerge in about 21 days (at 22°C). The larvae are rather inactive (in captivity) and are usually found on the underside of the thalli during the day. When disturbed or inactive the head may be withdrawn into the thorax. Pupation occurs within a thin walled, tightly woven brown cocoon close to the ground and attached to vegetation with strands of coarse silk.

Adults begin to emerge in late May with the flight season ranging from late May to mid- July and peak flight activity in June at the Prairie Creek State Redwood Park locality. Tuskes and Smith reported the adults to be relatively inactive, remaining motionless for hours and seldom travelling more than 30 cm. They are known to be diurnal and most active between 0900 and 1930 h. Adult feeding by Epimartyria pardella has not been reported, but the adults were observed drinking water by lowering their heads to the moisture. Moths can die in less than two days if deprived of moisture but may survive in captivity from 9 to 18 days when provided with water.

Tuskes and Smith concluded that Epimartyria pardella possessed a two year life cycle similar to that proposed for Epimartyria auricrinella ( Davis 1987). In captivity eggs deposited in June 1981 became adults in June 1983. In the field they frequently collected second instar larvae during the adult flight period.

Lectotype.

♂ (present designation), "OREGON: Klamath Co: nr. Redwood Creek, Coast: 26 June 1872, Wlsm. 90591; B.M. Genitalia Slide No. 25352; Epimartyria (= Micropteryx Wlsm.) pardella Wlsm. PARATYPE; Lectotype ♂, Epimartyria pardella Wlsm. (BMNH)." The lectotype has been selected from a series of five syntypes collected "on the borders of the forest of “redwood” ( Taxodium sempervirens ) near the coast, in southern Oregon, at the beginning of June 1872" ( Walsingham 1880).

Material examined.

UNITED STATES: CALIFORNIA: Humbolt Co: Arcata: 1 ♂, 11 Jun 1969, slide USNM 16613, wing slide USNM 18441 (USNM). Fern Canyon: 1 ♀, 18 Jun 1977, N. J. Smith, slide DRD 4529 (UCB). Fern Canyon, Prairie Creek State Park: 3 ♂, 19 Jun 1981, Ann & Paul Tuskes; 1 ♂, 20 Jun 1981, P. Tuskes, 3 ♂, Ann & Paul Tuskes (USNM). Kneeland: 69 Prairie Lane: 1 ♂, 17 Jun 2001, 2 ♂, 18 Jun 2001, 1 ♂, 29 Jun 2001, 1 ♂, 30 Jun 2001, R. S. Wielgus, diurnal flight in wet meadow below house, slide USNM 34278 (USNM); 1 ♀, 22 Jun 2003, R. S. Wielgus, slides DRD 4528, 4529 (UCB). Trinity Co: Forest Glen: 2 ♀, 25 May 1973, J. Doyen (UCB). OREGON: Klamath Co: nr. Redwood Creek, Coast: 1 ♂ (lectotype), 26 June 1872, Wlsm. 90591; B.M. Genitalia Slide No. 25352, (BMNH). Multnomah Co: Benson State Park, Multnomah Falls: 2 ♂, C. V. Piper, 1 ♂, wing slide USNM 91788 (USNM).

Distribution

(Fig. 32). Epimartyria pardella is known from northwestern California and northern Oregon. California localities and the type locality in Oregon are near the coast in redwood forests. The most northern Oregon locality occurs in the Columbia River valley.

Remarks.

Information included in this report on the immature stages and life history of Epimartyria pardella has been quoted or summarized from the thorough study of this species by Tuskes and Smith (1984) at the Prairie Creek State Redwood Park, California. In addition to possible color differences, two major morphological differences noted in their description of the larva of Epimartyria pardella from that observed for Epimartyria auricrinella include: (1) 10 versus 11 (in auricrinella) peg-like setae on each side of the prothorax, and (2) D2 of metathorax and abdominal segments 1-8 greatly reduced in pardella (as reported also in Austromartyria , Gibbs 2010, and for the abdomen in Agrionympha , Gibbs and Kristensen 2011). Although examples of the larva, pupa, and cocoon of this species were reportedly deposited in the collections of the California Academy of Sciences, San Francisco, CA by Tuskes and Smith (1984), attempts to locate and borrow this material for study were unsuccessful. The skeletomuscular anatomy of the male genitalia of Epimartyria pardella was reviewed by Kristensen (1984b).