Thyrocopa apatela (Walsingham)

Medeiros, Matthew J., 2009, A revision of the endemic Hawaiian genus Thyrocopa (Lepidoptera: Xyloryctidae: Xyloryctinae), Zootaxa 2202, pp. 1-47 : 13-14

5. Thyrocopa apatela (Walsingham)

( Figs. 13–14 , 68–70 )

Hodegia apatela Walsingham, 1907b: 488 , plate 14, fig. 2. Type species of Hodegia .

Lectotype: Thyrocopa apatela : UNITED STATES: HAWAII: Maui: Haleakala 9500’ [2896 m]: 1 Ƥ (slide 3955 BMNH, genitalia and wings), May 1896, Perkins (BMNH), designated by Zimmerman 1978: figs. 645, 950 (as “ holotype ”).

Thyrocopa apatela (Walsingham) ; Zimmerman, 1978: 937, figs. 645, 650, 650-A.

Thyrocopa mediomaculata Walsingham, 1907b: 506 , plate 15, fig. 5; Lectotype: UNITED STATES: HAWAII: Maui: Haleakala crater: 1 Ƥ (slide 3899 BMNH), Oct 1896, Perkins (BMNH), designated by Zimmerman 1978: figs. 660, 690 (as “ holotype ”).

Thyrocopa mediomaculata Walsingham ; Zimmerman, 1978: 988, figs. 660, 690. NEW SYNONYMY.

Diagnosis: Brachypterous individuals are easily recognized; they are the only wing-reduced Thyrocopa on Maui. Macropterous individuals can be difficult to separate from T. epicapna based on morphology; however, macropterous T. apatela almost always have larger blackish spots on the wings, and they occur at higher elevations on Maui than do T. epicapna .

Description: Head: Scales light brown to dark blackish-brown. Antenna ca. 0.8–0.9x forewing length; dense, extremely short, piliform cilia surround male flagellomere, though cilia sometimes difficult to see on dorsal side; female with extremely short, piliform cilia on ventral side of flagellomere. Labial palpus mottled very light brown to brown or dark blackish-brown; third segment ca. 0.9–1.2x length of second. Thorax: brown to dark blackish-brown. Forewing length 8–11 mm for brachypterous morph and 9–11 mm for macropterous morph; ground color brown with some darker brown scales scattered throughout; sometimes with poorly defined blackish spots, curving poorly defined whitish band through terminal area, and evenly spaced spots on distal half of costa and along termen at vein endings in macropterous morph; brachypterous morph with fainter, smaller spots and no whitish band or spots along termen. Brachypterous individuals with one lost M vein. Hindwing light brown with small dark area near apex in brachypterous individuals, and dark scales along anal margin in macropterous individuals; fringe brown in macropterous individuals and nearly absent in brachypterous individuals. Abdomen: Brown to dark blackish-brown. Male genitalia ( Figs. 68–70 ) with uncus scarcely cleft apically; sacculus moderately long, tapering to a point, with a scooped-out appearance. Female genitalia typical for genus; signum long.

Food plants: “Bunchgrass? The originally unique female holotype was shaken from a tuft of grass by Dr. Perkins” ( Zimmerman 1978). T. apatela is likely a generalist, feeding on Dubautia and other plant species found in the alpine scrub of Haleakala’s high elevation areas. F.G. Howarth reported finding T. apatela larvae feeding on wind-blown debris under small rocks ( Howarth 1979).

Flight period: May–August. This species is largely diurnal, though specimens occasionally come to light (S.L. Montgomery, personal communication). Typically, adults are collected while hopping between sunny rocks. No adults have been found during colder months of the year, despite extensive searching. Howarth (1987) wrote, “the adults hop in the wind and flutter along the ground in a manner similar to dry Dubautia leaves,” and suggested that this behavior helps adults locate suitable oviposition sites in accumulations of windblown leaves.

Distribution: This species appears to be undergoing severe range reduction. Although it was found as low as 1524 m in the 1970s, recent collecting indicates it is now restricted to areas above ca. 2900 m. This may be the result of the range expansion of introduced ants on Haleakala ( Krushelnycky et al. 2005). Lepidopteran larvae are found in significantly lower numbers in areas on Haleakala with ants compared with areas that have not yet been invaded ( Cole et al. 1992). Thyrocopa apatela appears to be more vulnerable to extinction by ant predation than other congeners; for example, T. epicapna is still found in similar dry, windy, scrubby habitats, including some that have large ant populations such as the Kanaha Pond area on Maui.

Remarks: I synonymize the brachypterous and flightless T. apatela and the macropterous and typically – though not always – volant T. mediomaculata for several reasons. First, there is a range of variation in wing size among specimens, though some strongly brachypterous individuals are missing the M-vein in the forewing ( Sattler 1991). Some individuals, such as specimen 04A22, are fully winged but flightless. And as Zimmerman (1978) wrote, “While this proof was being read, Klaus and Edith Sattler found fully-winged males of this species on Maui…” Second, the genitalia of both species are the same. Third, DNA evidence reveals that macropterous and brachypterous individuals form one, least-inclusive clade. For example, individual 04A22 is macropterous but genetically indistinguishable from brachypterous individuals (Medeiros, in preparation). Fourth, the habitat and collecting localities for these individuals overlap completely, and their resource use, feeding under rocks on dead leaves, is the same. This evidence indicates that there is only one species with considerable variation in flight ability and wing size. When collecting on Haleakala in 1976, Klaus Sattler wrote in his unpublished field notes, “It should be noted that we considered T. mediomaculata to be a macropterous morph of T. apatela .” Other Hawaiian Lepidoptera show similar variation (Medeiros et al. 2009), and T. apatela is likely a species that is undergoing selection for wing reduction and reduced flight ability. These themes will be discussed further, alongside a phylogeny of Thyrocopa (Medeiros, in preparation).

Contrary to the species list in Zimmerman (1978: 936), this species does not occur on Hawaii Island: a paratype of T. mediomaculata from the Big Island was misidentified and is T. abusa .

Several decades ago, Klaus Sattler searched for what Perkins (1913) described as “one or two similar forms” on the “open lower slopes” of Molokai for another flightless Thyrocopa , but was unable to locate a specimen. This species, if it in fact existed (and it was apparently never collected by Perkins), may now be extinct due to ant predation.

Additional material examined: UNITED STATES: HAWAII: Maui: East Maui, Haleakala National Park, Halemau’u Trail, 7400’ [2256 m]: 1 3, 27 Jul 1976, K. & E. Sattler ( BMNH); East Maui, Haleakala National Park, Sliding Sands Trail, 7450’ [2271 m]: 1 3 (slide 21906), 27 Jul 1976, K. & E. Sattler ( BMNH); East Maui, Haleakala National Park, Sliding Sands Trail, 9750’ [2972 m]: 8 3 (slide 28762), 3 Ƥ, 26 Jul–29 Aug 1976, K. & E. Sattler ( BMNH); Haleakala, 10,000’ [3048 m]: 1 3 (slide 19860 BMNH), 17 May 1965, J.W. Beardsley ( BMNH); Haleakala National Park, Kapalaoa, 2220 m, night collecting: 5 3, 4 Ƥ, 17–20 Jun 1976, F.G. Howarth ( BPBM); Haleakala National Park, Kapalaoa, 2220 m, night collecting: 1 3, 1 Ƥ, 17 Jun 1976, F.G. Howarth ( USNM); Haleakala National Park, Sliding Sands Tr.: 3 3 (slide 04A22), 11 Jul–25 Jul 2004, M.J. Medeiros ( HALE); Haleakala National Park, Sliding Sands Tr., 2630 m: 3 3, 17 Jun 1976, F.G. Howarth & R. Rice ( BPBM); Haleakala National Park, Sliding Sands Tr, 9600’ [2926 m]: 1 3 (slide 05A97), 1Ƥ (slide 05A98), 13 Jun 2005, M.J. Medeiros ( HALE); Haleakala National Park, Sliding Sands Tr.: 4 3, 1Ƥ, 24 May 2006, M.J. Medeiros ( HALE); Haleakala National Park, west slope crater rim: 1 3, 1Ƥ, 23 Jun 2003, P. Krushelnycky ( EMEC); Haleakala National Park, west slope crater rim, 2800 m, pitfall trap: 13 3, 8 Ƥ, 28 Jun 2003 – 24 Jul 1004, P. Krushelnycky ( BPBM); Kaupo Gap ridge, Haleakala, 5000’ [1524 m]: 2 3, 10 Jul 1976, S.L. Montgomery ( BPBM).

Figures

FIGURES 1 – 15. Adults of Thyrocopa. 1. T. abusa (holotype of T. immutata), Kauai, forewing = 11 mm; 2. T. abusa, Oahu, forewing = 11 mm; 3. T. abusa, Oahu, forewing = 9 mm; 4. T. abusa, Maui, forewing = 13 mm; 5. T. abusa, Maui, forewing = 12 mm; 6. T. abusa, Maui, forewing = 13 mm; 7. T. acetosa (holotype), Kauai, forewing = 10 mm; 8. T. albonubila, Kauai, forewing = 11 mm; 9. T. alterna, Maui, forewing = 11 mm; 10. T. alterna (holotype of T. adumbrata), Hawaii Island, forewing = 11 mm; 11. T. alterna, Hawaii Island, forewing = 15 mm; 12. T. alterna, Hawaii Island, forewing = 13 mm; 13. T. apatela (macropterous morph), Maui, forewing = 9 mm; 14. T. apatela (brachypterous morph), Maui, forewing = 8 mm; 15. T. apikia (holotype), Molokai, forewing = 14 mm.

FIGURES 60 – 74. Antenna and male genitalia of Thyrocopa; lower left box with detail of uncus, lower right box with detail of sacculus. 60. T. decipiens, Molokai, male, antenna; 61. T. vagans, Kauai, male, antenna; 62. T. kea, Kauai, male, abdomen showing transverse bands of spines (slide LA 59 UHIM); 63. T. indecora, Hawaii Island, male, detail showing very shallowly cleft uncus (slide 07 B 25 BPBM); 64. T. indecora, Hawaii Island, male, detail showing sacculus with scooped-out appearance (slide 07 B 25 BPBM); 65. T. abusa, Molokai, male genitalia (slide 31580 BMNH); 66. T. albonubila, Kauai, male genitalia (slide 07 A 85 BPBM); 67. T. alterna, Hawaii Island, male genitalia (slide Jon # 2 BPBM); 68. T. apatela (intermediate winged specimen), Maui, male genitalia (slide 05 A 97 HALE); 69. T. apatela (brachypterous morph), Maui, male genitalia (slide 19860 BMNH); 70. T. apatela (macropterous morph), Maui, male genitalia (slide 21906 BMNH); 71. T. apikia, Molokai, male genitalia (slide LA 26 UHIM); 72. T. brevipalpis, Kauai, male genitalia (slide 05 A 75 BPBM); 73. T. cinerella, Kauai, male genitalia (slide 08 A 24 BPBM); 74. T. decipiens, Molokai, male genitalia (slide LA 25 UHIM).