NOTA CIENTÍFICA

Redescription of the pupa of Parabezzia balseiroi (Diptera: Ceratopogonidae)

Redescripción de la pupa de Parabezzia balseiroi (Diptera: Ceratopogonidae)

Spinelli, Gustavo R., María M. Ronderos & Pablo I. Marino

División Entomología, Museo de La Plata, CCT CONICET- La Plata, Paseo del Bosque s/n, 1900 La Plata, Argentina; e-mail: spinelli@fcnym.unlp.edu.ar

Recibido: 23-VIII-2011
Aceptado: 21-XII-2011

ABSTRACT. The pupa of Parabezzia balseiroi Spinelli & Grogan was described and illustrated using binocular microscope, camera lucida and digital photographs. Pupae were captured along a stream margin in the Parque Provincial E. Tornquist Reserve, Sierra de la Ventana, Buenos Aires province, Argentina. Also, additional pupae were observed, measured and photographed on the basis of the type series deposited in the Museo de La Plata. Parabezzia balseiroi is compared with P. alexanderi Wirth, which was also herein studied and photographed from Nearctic specimens.

KEY WORDS. Parabezzia balseiroi; Pupa; Sierra de la Ventana; Argentina; Parabezzia alexanderi.

RESUMEN. Se describe e ilustra la pupa de Parabezzia balseiroi Spinelli & Grogan, utilizando microscopio binocular, cámara clara y fotografía digital. Las pupas fueron capturadas en el margen de un arroyo en la reserva Parque Provincial E. Tornquist, Sierra de la Ventana, provincia de Buenos Aires, Argentina. Asimismo, se observaron, midieron y fotografiaron las pupas de la serie tipo depositadas en el Museo de La Plata. Se compara Parabezzia balseiroi con P. alexanderi Wirth, la cual ha sido también estudiada y fotografiada en este trabajo, sobre la base de ejemplares neárticos.

PALABRAS CLAVE. Parabezzia balseiroi; Pupa; Sierra de la Ventana; Argentina; Parabezzia alexanderi.

The worldwide genus Parabezzia Malloch is a small group of poorly known biting midges, commonly breeding along the edge of more permanent bodies of water (Grogan & Wirth, 1977). Borkent & Spinelli (2007), in their catalog of the Neotropical ceratopogonids, recorded 24 species from this region which were reviewed by Spinelli & Grogan (1987). By virtue of the presence of a conspicuous basal swelling of the costal vein, Spinelli & Grogan (1987) recognized the alexanderi group, composed by five species: P. alexanderi Wirth, P. balseiroi Spinelli & Grogan, P. blantoni Wirth, P. costalis Wirth and P. spangleri Wirth. Of these, they described the pupae of P. alexanderi from eastern North America, Mexico, Belize, El Salvador and northeastern Argentina, and P. balseiroi from Mendoza, Corrientes and Entre Ríos provinces in Argentina. Although these are relatively modern descriptions, they are very incomplete.
The purpose of this paper is to fully describe the pupa of P. balseiroi from material collected during a recent entomological survey in Sierra de la Ventana, Buenos Aires province, Argentina. In addition, the pupal exuviae of P. alexanderi is herein studied, photographed and compared with P. balseiroi. Due to the possibility of a synonymy of these species based on the adult similarity the detailed study of their pupae is strongly needed to clarify the identification problem. The improvement in the knowledge of the pupae of ceratopogonids in the last years has allowed to determine the differences which, although minimum, make possible the distinction of the two species in this study.
Female pupae of P. balseiroi were collected with pipette from a white tray with muddy water from the edge of a stream margin in the Reserva Natural Parque Provincial Ernesto Tornquist in Sierra de la Ventana, Buenos Aires province, Argentina. They were carried back to the laboratory and conditioned in vials, individually, with a drop of water. Observations were done daily, until adult emergence. For microscopic observation, pupal exuviae were slide-mounted in Canada balsam following the technique described by Borkent & Spinelli (2007). They were mounted ventrally to examine cuticular processes of the cephalothorax, respiratory organs, and abdominal segments. All the illustrations were made with camera lucida. Photographs were taken with a Pentax Optio Power Shot S60 digital camera through a Leitz SM-Lux (10x or 40x). All the images were assembled in Photoshop CS4.
Male pupal exuviae of P. balseiroi were described from the type-series, represented by specimens slide mounted in Canada balsam following Wirth & Marston (1968).
Male and female pupal exuviae of P. alexanderi, also slide mounted in the manner of Wirth & Marston (1968), were studied and photographed from Nearctic specimens housed in the Florida State collection of Arthropods, Gainesville, Florida, USA (FSCA). For terminology see Borkent & Craig (2001). Studied specimens of P. balseiroi are deposited in the collection of the Museo de La Plata, Argentina (MLPA).

Parabezzia balseiroi Spinelli & Grogan, 1987 (Figs. 1-3, 7-9, 14-18)

Figs. 1-6. Female pupa: 1-3, Parabezzia balseiroi, 4-6, Parabezzia alexanderi; 1, 4, cephalothorax, lateral view; 2, 5, operculum; 3, 6, anal segment. Anteromarginal setae (am); antenna (AN); anal segment (AS); apicolateral processes (AP); crest (c); dorsal sensillae (d); foreleg (fl); hindleg (hl); midleg (ml); pedicel (P); pore (p); pore at tubercle base (ps); respiratory organ (RO).

Figs. 7-13. Male pupa: 7-9, Parabezzia balseiroi, 10-13, Parabezzia alexanderi; 7, 10, cephalothorax, ventral view; 8, 12, operculum; 9, 13, anal segment; 11, ventromedian setae. Anteromarginal setae (am); antenna (AN); anal segment (AS); apicolateral processes (AP); fore leg (fl); genital sac (GS); hind leg (hl); labium (Lb); mid leg (ml); operculum (O); pedicel (P); pore (p); pore at tubercle base (ps); respiratory organ (RO); thoracic plate (tp); ventrolateral setae (vl); ventromedian setae (vm).

Figs. 14-23. Female pupa: 14-18, Parabezzia balseiroi, 19-23, Parabezzia alexanderi; 14, 19, tubercles of cephalothorax; 15, 20, dorsal setae; 16, 21, ventromedian and ventrolateral setae; 17, 22, 1^st abdominal segment; 18, 23, 4^th abdominal segment. Scale bars 0.05 mm. Anterodorsal setae (ad); dorsolateral seta (dl); dorsomedial setae (dm); spiracular scar (sp.s); ventrolateral setae (vl); ventromedian setae (vm). Fourth abdominal segment setae: dorsal posteromarginal setae (d.p.m.); dorsal anterosubmarginal setae (d.a.s.m.); lateral posteromarginal setae (l.p.m.); ventral posteromarginal setae (v.p.m.).

Parabezzia balseiroi Spinelli & Grogan, 1987: 13 (female, male, pupa; Argentina); Spinelli & Wirth, 1993: 49 (in list of Argentinean species); Borkent & Wirth, 1997: 104 (in World catalog); Spinelli, 1998: 326 (in list of Argentinean species); Borkent & Spinelli, 2000: 51 (in catalog species south of USA); Spinelli, 2000: 70 (distribution); Borkent & Spinelli, 2007: 84 (in Neotropical catalog); Borkent, 2011: 127 (online catalog).

Diagnosis adult. Only Neotropical species of the Parabezzia alexanderi group with basal costal swelling non detached, costal section III separate from vein M₁, legs mostly yellowish, r-m crossvein at an oblique angle, and female claws on fore and mid legs equal.

Redescription of female pupa (Figs. 1-3, 14-18). Length (including apicolateral processes) 2.85-3.60 (3.22, n = 10) mm. Exuviae pale brown, body surface smooth. Operculum (Fig. 2) with anterior margin quadrangular, posterior margin truncated, disk with longitudinal wrinkles on anterior portion, lateral margin with broad raised areas with well developed anteromarginal tubercle (am) bearing minute seta, pore at tubercle base, OL 0.056-0.080 (0.066, n = 9)  mm, OW 0.200-0.296 (0.257, n = 10) mm, OW/OL 3.3-4.1 (3.6, n = 9). Labrum, mandibular, maxillary, labial sheaths well developed, palpal sheath medium-sized (Fig. 16). Cephalothorax surface smooth, with medium-sized medial crest extending between bases of respiratory organs (Fig. 1). Cephalothorax length 1.10-1.32 (1.18, n = 10) mm, width 0.78-0.82 (0.80, n = 7) mm. Two anterodorsal setae (ad), one minute seta, one pore (Fig. 14); one short, stout dorsolateral seta (dl) (Fig. 14); two minute, stout dorsomedial setae (dm) (Fig. 14). Dorsal sensillae (d) and thoracic tubercles (Figs. 1, 15): i-ii peg, iii pore on tubercle I, iv pore on tubercle II, tubercles III, IV without sensillae. Respiratory organ (Fig. 1) 2.5 longer than broad, dark brown, short, with 10-12 apical opening pores in two rows, RO length 0.084-0.116 (0.100, n = 10) mm, RO width 0.038-0.046 (0.041, n = 10) mm, base slightly tapered; pedicel slightly pale, smooth, short, pedicel length 0.012-0.022 (0.018, n = 10), P/RO 0.12-0.22 (0.18, n = 10). One ventromedian, short, strong seta (vm); one ventrolateral (vl) pore (Fig. 16). Abdominal segments integument smooth, tubercles poorly developed. First abdominal segment as in Fig. 17; anterior edge with two minute setae on small tubercle; lateral portion with two minute setae, one pore; mesal portion with one pore, two minute setae. Fourth abdominal segment with sensillar pattern (Fig. 18) as follows: one dorsal anterosubmarginal (d.a.s.m.), medium-sized, stout seta; 3 dorsal posteromarginal (d.p.m.) setae: i stout, black, minute seta, ii-iii absent, iv pore, v short seta, base rounded; lateral anterosubmarginal (l.a.s.m.) absent; 3 lateral posteromarginal (l.p.m.): i pore, ii-iii short seta, all on triangular, strong tubercles; ventral anterosubmarginal (v.a.s.m.) absent; 2 ventral posteromarginal (v.p.m.) setae: i, short, stout seta on raised, triangular base; ii, minute, hyaline seta. Female anal segment (Fig. 3) with dorsal surface smooth, only few spicules on anterior edge, ventral surface with spinules, apicolateral processes triangular with ventral pore at mid portion, medium-sized, base wide, slightly divergent, extreme tip slightly clear; anal segment length (with apicolateral processes) 0.344-0.400 (0.37, n = 10) mm, width 0.176-0.264 (0.20, n = 10) mm, apicolateral processes length 0.136-0.170 (0.153, n = 10) mm.

Male (from type-series) (Figs. 7-9). Similar o female with sexual differences. Length including apicolateral processes) 2.70-3.08 2.93, n = 5) mm. Operculum (Fig. 8) longer han female, anteromarginal tubercle longer han female, with setae on anterior edge; OL 0.074-0.084 (0.078, n = 5) mm, OW 0.190-0.216 (0.197, n = 5) mm, OW/OL 2.26-2.84 (2.54, n = 5). Respiratory organ (Fig. 7) length 0.084-0.112 (0.096, n = 5) mm, pedicel length 0.014-0.020 (0.016, n = 5) mm, P/RO 0.145-0.187 (0.166, n = 5). Anal segment (Fig. 9) length 0.344-0.376 (0.36, n = 5) mm, width 0.224-0.24 (0.23, n = 5) mm, apicolateral processes length 0.116-0.156 (0.14, n =5) mm.

Distribution. Argentina (Mendoza, Corrientes, Entre Ríos, Buenos Aires provinces).

Bionomics. The development of the pupa of P. balseiroi was completed in 4 days when placed individually in cotton-stopper vials. The emergency of adults reared in laboratory was produced at T 22°-26° C (24° C) and H 42-45 % (43 %).

Examined types of P. balseiroi. Holotype female with pupal exuviae, allotype male with pupal exuviae, Argentina, Entre Ríos, Santa Ana, 23-IX-1984, E. Balseiro-G. Spinelli, collected as pupae, reared in laboratory. Paratypes, 6 females, 12 males, as follows: same data as holotype, 3 males; same data except 9-XI-1984, 9 males, 6 females. All specimens were collected as pupa along a pond margin associated with filamentous algae, and reared in laboratory (MLPA).

Other examined specimens
Parabezzia balseiroi: Argentina, Buenos Aires, Sierra de la Ventana, Reserva Parque Provincial E. Tornquist, arroyo de la Clausura, 38º 02' 46.1'' S, 61º 59'10.1'' W, 19-XII-2006, F. Díaz, 2 females with pupal exuviae; same data except 23-III-2007, P. Marino-C. Cazorla, 1 female. All specimens were collected as pupae along a stream margin and reared in laboratory (MLPA).
Parabezzia alexanderi (Figs. 4-6, 10-13, 19-23): USA, Maryland, Prince Georges Co., College Park, Lakeland Pond, 30-V-1975, W.L. Grogan, 1 male with pupal exuviae; same data except 10-IX-1975, 1 female. Specimens collected as pupa along a pond margin and reared in laboratory.

Remarks. As it was pointed out by Spinelli & Grogan (1987), adults of P. balseroi and P. alexanderi are nearly identical except for the length of tarsal claws which are equal on fore and mid legs in P. balseiroi, and unequal in P. alexanderi. The strong similarity of the adults of both species is correlated with the slight differences showed by their pupae. The following are the differences observed in the pupa of P. alexanderi when it was compared with P. balseiroi:

• The lateral margins of the operculum are not as raised as in P. balseiroi, and the anteromarginal tubercle is less developed (Figs. 5, 12).
• The respiratory organ bears 14-16 apical opening pores (Fig. 10).
• The dorsomedial setae are represented by one seta and one pore (Fig. 19).
• The dorsolateral seta is stouter and shorter, peg-like (Fig. 19).
• The ventromedian seta is minute, and the male shows an additional pore (Figs. 11, 21).
• The first abdominal segment has a single seta on its anterior margin (Fig. 22).
• The apicolateral processes have a narrow base, are subparalell, and bear two pores at their mid portion (Figs. 6, 13).

ACKNOWLEDGEMENTS

Our gratitude to Dr. William L. Grogan, who kindly sent to us specimens of P. alexanderi from the Florida Collection of Arthropods, Florida, USA. We also acknowdedge Florentina Díaz and Nélida Caligaris for technical assistance and Mónica A. Caviglia for the English proofreading.

LITERATURE CITED

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