Rivula stepheni Sullivan, 2009

Sullivan, J. Bolling, 2009, A New Species of Rivula Guenée (Lepidoptera, Noctuidae) from Southeastern United States, ZooKeys 9 (9), pp. 3-10 : 5-8

Rivula stepheni Sullivan , sp. n.

urn:lsid:zoobank.org:act:D97F6D3C-55D4-4C19-B5CA-24DFF70646AE

Figs. 3-6 , 11

Type locality. MacPherson Creek, Ft. Bragg, Cumberland County, North Carolina, USA.

Type material. Holotype, male: USA, North Carolina: Cumberland Co., Ft. Bragg, MacPherson Creek , 20 Jun 2001, J. B. Sullivan ( USNM) . Paratypes: 29 ♁, 3 ♀: USA, North Carolina: Onslow Co., Camp LeJune, Verona Loop, 25 Jul1995 (♁) ; Craven Co., Croatan National Forest Rd. 147, 22.Apr.1996 (♁) ; Croatan National Forest Rd. 3046, Craven Co., 7.Apr.1998 (♁) ; Craven Co., Croatan National Forest Rd. 169, 16 Aug 1999 (♁) ; Cumberland Co., Ft. Bragg, MacPherson Creek , 21 Jun 2001 (♁) ; Craven Co., Havelock, off Sunset Drive , 31 Aug 2005 (♀) and 27 Sep 2005 (♁) ; Jones Co., Croatan National Forest , Haywood Landing, 24 Jun 2006 (♁) ; Craven Co., Croatan National Forest Rd. 3046, 20 Jun 2008 (2 m), all collected by J. B. Sullivan ( BMNH, USNM, JBS) . Louisiana: St. John the Baptist Parish, Edgard, 4 Sep 1975 (♁) ; 4.2 mi NE of Abita , 25 Oct 1984 (♁), 16 Sep 1986 (♁), 8 Oct 1989 (♁), 29 Aug 1992 (♁), 24 Sep 1994 (♁), 25 Sep 1994 (♁), 30 Sep 1994 (♁), 3 Oct 1994 (♁), 16 Oct 1994 (♁), 29 Oct 1994 (♁), 26 Sep 1995 (♁), 4 Oct 1996 (♁), 10 Oct 1996 (♁), 11 Oct 1996 (♁), 29 Oct 1997 (♁), 6 Oct 1997 (♁), 26 Oct 1998 (♁), 20 Sep 2002 (♁), 23 Dec 2002 (♀), 15 Jun 2005 (♁) ; West Feliciana Parish, Weyanoke , 8 Sep 1980 (♀), all collected by V. A. Brou, Jr. ( CNC, VAB) .

Other material examined. One additional specimen was examined from pictures supplied by Hugo L. Kons, Jr.: Florida, Gadsden Co., south side of Dolan Road, 0.1 miles W. of Hwy. 269, 23 May 1999, UV light trap, Hugo L. Kons, Jr. and Robert J. Borth .

Etymology. This species is named for Stephen A. Hall of the North Carolina Natural Heritage Program, whose tireless work to preserve natural habitats in North Carolina and to describe the natural communities in those habitats has greatly enriched the people of North Carolina.

Diagnosis. Rivula stepheni is a plain, ivory-colored species with scattered black markings but easily distinguished from other species with which it might be confused. Rivula propinqualis has a smooth diagonal postmedial line that approximately follows the line of the wing margin. In R. stepheni it is less well marked but clearly undulated. Additionally, there is a moderately large black spot (coastal plain specimens) or smudge (mountain specimens) along the forewing costa near the apex of the wing in R. propinqualis but two very small dots in R. stepheni . Macrochilo louisiana (Forbes) is superficially similar but has prominent labial palps. Wear quickly eliminates some of the scattered black markings in R. stepheni .

Description. Male ( Figs. 3, 4 ): Head – antenna fasciculate, setae approximately length of shaft diameter; scape white; antenna scaled dorsally, white basally, becoming tan terminally; length of shaft 60 % of wing length; lower half of frons covered with straw to tan flattened scales; upper half of frons white medially, tan laterally, with narrow scales overlain with broader scales, all of which point anteriorly projecting over lower frons; eye without setae, slightly flattened toward thorax, scaling around eye straw to tan colored.; ocellus present; tongue normal; labial palp slightly porrect anteriorly,

flattened dorsally; second segment 3 × longer than other two segments, broadly scaled dorsally and with large flattened scales ventrally, color tan on exterior, straw on interior; neck and collar covered with white scales. Thorax – with flattened scales overlaying pointed scales, with occasional darker scales intermixed; tegulae scales and coloration similar to remainder of thorax; leg scales white and straw with darker scales scattered throughout; prothoracic femur with grey scaling dorsally. Forewing – length 8.2-10.2 mm; ground color ivory with darker tan scaling along margins; reniform spot visible as two black spots, upper one slightly closer to thorax; basal black spot between vein Sc and R1; wing margins with tan scaling, a spot formed at extremity of each major vein; cross lines visible but often very diffuse. Hindwing – similar to forewing but without black spots. Underside similar to upperside but may be darker and without reniform or basal spots; retinaculum on base of costa, neither bar-like nor well defined. Abdomen – scales blunt tipped, white with occasional dark scales scattered throughout, particularly posteriorly. Male genitalia (Figs. 5, 6) – valves symmetrical; uncus elongate, widest in middle, knife shaped, setae found over entire surface but longest dorsally; base of uncus forms a window at junction with tegumen; gnathos and socii absent; anal tube strongly sclerotized dorsally; tegumen arms broad, forming inverted “V;” vinculum U-shaped, narrower, articulating directly with base of tegumen without pleural sclerite; valva 1.62 mm long, unsclerotized, membranous, with a subbasal broad, rounded ampulla covered with pimple-like processes bearing setae; costa excavated at base; juxta lightly sclerotized and difficult to see; transitilla membraneous; aedeagus: length 0.41 mm, short, stout, with ductus entering at base; vesica with two principal diverticula;

base with band of short tooth-like projections; two diverticula separated by a broad, sclerotized, thumb-like disc; larger evagination on left covered with sharpened, peg-like cornuti over entire surface but largest on dorsal side; right diverticulum slightly scobinate. Female – similar to male except antennal setae sparse. Female genitalia (Fig. 11) – anal papillae with pimples bearing setae on inner surface; outer surface with long sparsely placed setae; each papilla triangular with blunt tip; posterior apophyses slightly longer than anterior ones, slender, with slightly rounded tips; ostium membranous, ductus bursae lightly sclerotized and striated, moderately thickened; corpus bursae with accessory bursa posteriorly on right side; posterior half of corpus bursae cylindrical, 2-3 × as broad as ductus bursae and slightly striated; anterior half of corpus bursae forming heart-shaped chamber containing three embedded plate-like signa; two signa situated posterior to third signum, all well sclerotized; total length of female genitalia 3.93 mm.

Distribution and biology. Initially thought to be limited in distribution to eastern North Carolina, a picture of an unknown moth collected in Gadsden County, Florida by Hugo Kons, Jr. and Robert Borth was provided and is Rivula stepheni . All North Carolina specimens were found in mesic mixed pine and hardwood forests near small streams with cane ( Arundinaria spp.) growing nearby. The adjacent upland areas contain both hardwoods and loblolly pine ( Pinus taeda L.) with American holly ( Ilex opaca Ait. ) and witch hazel ( Hamamelis virginiana L.) in the understory. Typically, cabbage palmettos ( Sabal palmetto (Walter) Lodd. ex Schult. & Schult. f.) are in the floodplain of the stream. Grasses and small sedges are common in the floodplain area and both Rivula propinqualis and R. stepheni have been found in the same trap. The Florida specimen was collected on May 23, 1999 in Gadsden County in essentially identical habitat (Hugo Kons, Jr., personal communication). North Carolina specimens have been captured from early April ( Fig. 4 ) through September indicating that the species bred continuously in the area (likely representing three or four broods). Summer captures are most common and spring specimens are approximately 20 % larger than individuals from subsequent broods (see Sullivan and Miller 2007).

Twenty two additional specimens were collected by Vernon A. Brou, Jr. in Louisiana, primarily at his home near Abita Springs. These specimens were collected during an extensive year round trapping program ongoing statewide for 40 years. They were taken in June (1), August (1), September (8), October (10), November (1), December (1) and each was a singleton capture in one of six traps operated each night. This would indicate that the species is not breeding at the trapping site but instead is wandering into the trapping area from some presumed nearby site. Rivula pusilla is known to migrate late in the year into the Gainesville, Florida area in some years (Hugo Kons, Jr., personal communication) and the European R. sericealis is known to migrate within Europe and to Britain ( Sparks et al. 2007; Wood et al. 2009). Captures in the Abita Springs area may derive from a similar wandering/migratory behavior in the fall and their infrequent occurrence would indicate that the species is limited in distribution in Louisiana as well as in Florida and North Carolina.

Reported host plants for species of Rivula are grasses and sedges. Larvae pupate in loose cocoons covered with debris (figured in Kitching and Rawlins 1999).

Figures

Figures 1-4. Adult Rivula. 1. Rivula pusilla Möschler. 1.4 mi WSW Anthony, Marion Co., Florida, 2 Jan. 2006, Terhune Dickel. 2. Rivula propinqualis Guenée. Edmundston, New Brunswick, 8 Sept 1987, Henry Hensel. 3. Rivula stepheni Sullivan. Holotype. Macpherson Creek, Ft. Bragg, Cumberland Co., N.C., 20 June 2001. J. Bolling Sullivan. 4. Rivula stepheni Sullivan. Croatan National Forest Road 3046, Craven Co., N.C., 7 April 1998, J. Bolling Sullivan.

Figures 11-12. Female genitalia of Rivula. 11. Rivula stepheni Sullivan. Craven Co., N. C. (JBS 2212). 12. Rivula propinqualis Guenée. Alleghany Co., N. C. (JBS 2210).