Paracles vulpina (Hübner, [1825])

Beccacece, Hernán Mario, Viglione, Gabriela Bentancur, Graff, Pamela & Morelli, Enrique, 2021, Redescription of Paracles vulpina (Hübner, [1825]) (Lepidoptera: Erebidae), with comments of the aquatic habit of larval instars, Zootaxa 5061 (1), pp. 157-166 : 159-164

Paracles vulpina (Hübner, [1825])

Antarctia vulpina Hübner, [1825] : pl. [193], figs. 1-4

Purius? vulpinus Walker, 1856: 1782 [new combination proposed]

Arctia pallicosta Boisduval, 1859: 158 [synonymized by Berg, 1899: 377]

Paracles vulpina (Hübner) ; Watson & Goodger, 1986: 32 [new combination proposed] Type material. Undisclosed number of syntypes. These specimens could be lost or destroyed ( Vincent & Laguerre 2014).

Redescription ( Fig. 2a–f ). Male ( Fig. 2a–b ): body completely covered with a great density of long hairs. Head: brown dorsally and dark brown ventrally. Posterior margin of the scape and eye edge light brown-orange. Antenna strongly bipectinate, whitish, and rami light brown. Palpi dark brown, erect, and directed to the ventral area. Proboscis reduced, no longer than the head, possibly not functional. Thorax: brown dorsally and dark brown ventrally. Legs: brown except the dorsal side of coxa, trochanter, and femur light brown-orange. Forewing – length 17-18 mm: shining brown dorsally with paler costa. Ventrally white except outer margin and apex darker and coastal area brownish. Hindwing – length 14-15 mm: dorsal and ventral white except the coastal and basal areas light brown-orange. Abdomen: brownish-orange dorsally and dark brown ventrally except the last segment the same as dorsal. There are darker specimens with same pattern. Male genitalia ( Fig. 2d ): genital capsule rhomboid. Uncus subtriangular with base rounded and apex finger-shape, curved ventrally; tegumen slightly rounded with an invagination at middle; juxta wide and trapezoidal; vinculum slightly rounded; saccus wide and broadly rounded; valvae shorter than uncus, with sacculus and costa fused, flattened and slightly directed towards the internal region; aedeagus ( Fig. 2e ) curved and slightly shorter than the genital capsule, caecum present and vesica membranous. Female ( Fig. 2c ): Externally similar to males except for the following features: larger and more robust, antennae with smaller rami. Forewing – length 24- 20 mm: Brown dorsally with paler costa. Ventrally dark except base which is white and first part of costa which is brownish. Hindwing – length 14-15 mm: dorsally paler brown than forewing and inner margin whitish brown. Ventrally darker and base withish brown. There are darker specimens with same pattern. Female genitalia ( Fig. 2f ): Papillae anales subquadrangular and setose. Pheromone gland tubelike, short, reaching the apophyses posteriores. Apophyses anteriores shorter than posteriores. Ductus bursae short, flattened, and sclerotized, tube-like. Corpus bursae oval, membranous with a circular striated band. Two rounded signa, sclerotized and present at the base of the corpus. Appendix bursae globose, membranous and similar in dimension to corpus bursae.

Immature stages ( Figs. 3a–d , Fig. 4 ). Eggs ( Fig. 3a ): whitish, disposed in a mass and covered with pale scales. Larvae ( Figs. 3b–c , Fig. 4 ): eruciform, very pubescent with a dark general color, with a very compact dorsal line of yellow silks. Body length up to 39 mm. +/– 3 mm.Aeriferous plastron present in T2-A9. Thoracic plastron with tufts of crisscrossed silks tightly packed and abdominal plastron airframe formed by plumes of tight white silks. Head: shiny black and rounded. Thorax ( Fig. 4a ): T1 plastron absent, dorsal, subdorsal and lateral verrucae blue; T2-3 plastron gray and verrucae same as T1 ( Fig. 3d ). Abdomen ( Fig. 4b ): A1 plastron gray and verrucae same as T1; A2 plastron white, dorsal and subdorsal verrucae blue, and lateral and subventral verrucae red; A3-8 plastron white, dorsal verrucae blue, and sublateral, lateral and subventral verrucae red;A9 plastron white, and dorsal, subdorsal, and lateral same as T1. Cocoon ( Fig. 3d ): cocoon elliptical, tapered at both ends, with circular emergency area. Maximum length 38 mm. All the cocoon wrapped in a loose weaving of light gray silks, compact cocoon with an interweaving of parchment-like appearance. The cocoon is made of grey soft silk, the long black hairs of the caterpillar are woven into the outer layer and with the white hairs the inner. Pupa male ( Fig. 3d ): Smooth tegument, caramel brown color, length 21 mm, and maximum width 8 mm. General elliptic shape, quadrangular broad front with slightly sinuous edges. Clipeus broadened, continuing the front edges with a slight lateral notch on each side, continuing in a rounded labyrinth. Labial palps with a wide base, tapering towards the end. Mouthpieces and antennae reach the edge of the metathorax. The meso and metathoracic podothecs visible, wide and with sinuous edges, tapering towards the apex. Antennae with visible external segmentation, somewhat shorter than the metathoracic podothec. Ceratothecas hardly visible accompanied the lateral edge of the pterothec. Pupae with seven free segments in the ventral area. Cremaster formed by a compact group of short and thick silks of bright amber color. Metathoracic spiracle visible, seven abdominal spiracles, from second to eighth segment. Anal slit transversely elongated framed in a pair of anal pads. Transverse short gonopore over a small blister in the ninth abdominal segment.

Biology. Females put the egg masses on the underside of the grass and cover them with a dense tuft of scales of the anal area. The caterpillar from Uruguay was found on aquatic plants in a lentic system and only ate Azolla at night. The pupae stage lasted for 21 days. On the other hand, hundreds of larvae (e.g.: 274 larvae in 12 m 2) from the Flooding Pampa grassland in Buenos Aires ( Argentina) were found feeding on different grasses such as Schenodorus arundinaceus (= Festuca arundinacea , tall fescue), Lolium multiflorum (annual ryegrass), Paspalum dilatatum , and P. paludivagum (native grasses). They were observed swimming and looking for new food resources but feeding out of the water ( Fig. 1b ; https://youtu.be/_cbyrf7-cDo). A total of 18 larvae of the 30 individuals collected and feeded with Bromus catharticus pupated. This stage lasted 22.33 days (± 0.43 S.E.) before developing a moth.

Distribution. Eastern Brazil, Uruguay, and central and eastern Argentina ( Burmeister 1878; Köhler 1926; Breyer 1930; Pastrana 2004; Teston & Corseuil 2004; Ferro & Teston 2009; Formentini et al. 2015).

Material examined (adults). 5 males and 1 female: Buenos Aires (locality information in Table 1 , all dissected), MZUC. 10 males and 2 females: Córdoba (locality information in Table 1 , 2 males dissected and 1 female dissected), MZUC. 1 male: Santa Lucia, FCEL (locality information in Table 1 ) .

Discussion

The adults of P. vulpina can be differentiated from other species of Paracles by the presence of a whitish paler brown band in costal area of forewing and whitish paler brown antenna in both sexes. These are the main diagnosis to identify the species. The habitus is similar to the type species of the genus: Paracles contraria Walker 1855 ( Vincent & Laguerre 2014; Drechsel & Drechsel García 2016b) except for the ground color of this latter. Previous studies did not agree with some taxonomic rearragement proposed concerning P. vulpina ( Burmeister 1878; Hampson 1920; Strand 1919). These disagreements are because the type material of some species is lost, the type locality was not correctly specified in the original description and the original illustration representing the species is not enough detailed, e.g. P. vulpina (Type locality: South America ) and Paracles brunnea (Hübner, [1831; Type locality: Montevideo [ Uruguay]). Concerning these two species, Burmeister (1878) was the first to consider P. brunnea as a variation of P. vulpina . However, Hampson (1901) and Köhler (1926) omitted this synonymy and they commented that these two species can be differentiated on account of the larger pectination of the antenna, costal margin of forewing without a pale color band, and hindwing darker in P. brunnea . The habitus description used by these authors for P. brunnea is very different from P. vulpina and even, it is more similar to Paracles severa (Berg 1875) . Strand (1919) also considered P. brunnea as a valid species in his catalogue. We found darker specimens in PN Condorito (Córdoba, Argentina), as Burmeister (1878) observed, and the genitalia is exactly the same as brownish specimens. A more careful study is needed using material from different localities or new collects to confirm if P. brunnea is or not a synonym of P. vulpina . On the other hand, it is necessary to discuss the status of Paracles felderi (Rothschild, 1910) because the habitus is very similar to P. vulpina . In fact, Hampson (1920) was the first to propose this species as a junior synonym of P. vulpina and later omitted. In this article, we show for the first time the male and female genitalia of P. vulpina and this will contribute to clarify the status of these species in further studies.

In the present study, the life cycle was not studied completely because we could not follow all stages. For this reason, more studies are necessary to know the number and differences of instars and development times for each stages. The female oviposits masses of eggs on the hostplant and cover them with a tuft of withish scales from the anal area. This particular habit is a common behaviour in different species of Paracles ( Köhler 1926) and other Lepidoptera and it seems to act as an egg protection against predator or weather climate ( Floater 1998). Regarding the larvae of P. vulpina , we improved the previous information of Köhler (1926). He only provided superficial characteristics of the coloration pattern and the number of verrucae and their disposition. We agree with this author about the characteristics of the larvae provided by Seitz (1920) are not from P. vulpina but correspond to Paracles fusca (Walker, 1856) . This last species has a general brown greyish coloration, verrucae are red pinkish and the white yellowish dorsal band is visible because the setae of the plastron are shorts ( Laplanche 2016). Rothschild (1911) also presents a lateral view illustration of P. vulpina larva. However, this is not useful because some important details to recognize this species are not visible. The last instar of Paracles vulpina can be differentiated from other species such as P. contraria and P. azollae because P. vulpina shows body with a black pubescence except for a ferruginous subventral pubescence, blue dorsal verrucae, red lateral verrucae, and dorsal plastron with longest white setae. P. contraria shows blue greyish marbled localized pubescent area, black lateral verrucae, and dorsal plastron with ocher yellowish shorter setae in well-defined areas. Finally, P. azollae shows a body with jet black pubescence, reddish lateral verrucae, and dorsal plastron with white well-compacted setae ( Laplanche 2018; Morelli et al. 2018). About the pupa, this is here the first time this stage is described and shown. Köhler (1926) briefly described the cocoon. This stage has the same common characteristics than other Arctiinae .

Larvae of P. vulpina have been previously reported feeding on several plants from different families such as Cucurbita maxima (Fam. Cucurbitaceae ), Medicago sativa , and Glycine max (alfalfa and soybean; Fam. Fabaceae ), Quercus robus (oak; Fam. Fagaceae ), Juglans regia (walnut; Fam. Juglandaceae ), Dactylis glomerata (Orchardgrass; Fam. Poaceae ), Populus nigra and Salix humboldtiana (poplar and willow; Fam. Salicaceae ), Cupania vernalis (camboatá; Fam. Sapindaceae ), and Tilia cordata (linden; Fam. Malvaceae ; Hayward 1969; Pastrana 2004; Formentini et al. 2015). However, this information should be corroborated because an incorrect identification of the larvae could have happened. On the other hand, Köhler (1926) also commented that the larvae can feed on different herbaceous plants species. As shown previously, we observed several larvae feeding on different Poaceae such as the invasive grass Schenodorus arundinaceus (= Festuca arundinacea , tall fescue) ( Graff et al. 2020), and Lolium multiflorum (annual ryegrass), both endophyte-infected plants with alkaloid compounds. The larvae were also observed on native grasses species such as Paspalum dilatatum and Paspalidium paludivagum , and they accepted Bromus catharticus as foodplant. A single larva was registered feeding of the aquatic plant Azolla in Uruguay. The evidence of the polyphagia and the possibility to consume toxic plants can be related to supplementing endogenous defenses by sequestering compounds from their host plants ( Zaspel et al. 2014). Regarding the biology of caterpillars observed in the field, the aquatic larval habit is not a necessary strategy and it could be used depending on the ground topography or weather of the place.

Despite similar dull coloration of the Paracles adults, this speciose genus is maybe not a monophyletic group because there are important differences on the habitus, genitalia and immature stages of several species ( Becker & Miller [1991]; Meneses et al. 2013; Drechsel 2014; Drechsel & Drechsel García 2016a, b, 2017). For this reason, it is necessary to make a full review of Paracles . The aquatic habits of larvae instars could be a character to consider. However, more studies of life-cycles and natural history of the Paracles species are needed.

Figures

FIGURE 1 Localities and environments where larvae and adults of Paracles vulpina were found. a Map of South America and a closer view of the localities. Red squares = Localities, b Flooded Pampa, Buenos Aires, Argentina. Black circles: larvae eating grass, c Grassland and Caragüatales of Santa Lucía, Montevideo Department, Uruguay, d High grassland, Quebrada del Condorito National Park, Córdoba, Argentina.

FIGURE 2 Habitus and genitalia of Paracles vulpina (Hübner, [1825]). a Dorsal (left) and ventral (right) view of adult male, b Dorsal (left) and ventral (right) view of darker adult male, c Dorsal (left) and ventral (right) view of adult female, d Male genitalia, e Aedeagus, f Female genitalia. Scale bar: 10 mm.

FIGURE 3 Immature stages of Paracles vulpina (Hübner, [1825]). a Egg masses on grass leaves and emergence of the first instar stage, b First instar stage, c Last instar stage, d Cocoon and pupa.

FIGURE 4 Chaetotaxy of the last instar of Paracles vulpina (Hübner, [1825]). a Thorax, b Abdomen. T1 (prothorax) Vd (dorsal verruca), Vsd (subdorsal verruca), Vl (lateral Verruca), T2-3 (meso and metathorax), Pl (Plastron), A1-9 (abdominal segments 1 to 9), Vsv (subventral verruca).