Description of Larva and redescription of Pupa and Adult of Palpomyia guarani (Diptera: Ceratopogonidae)

Descripción de la larva y redescripción de pupa y adulto de Palpomyia guarani (Diptera: Ceratopogonidae)

Ronderos, María M., Gustavo R. Spinelli, and Florentina Díaz

División Entomología, Museo de La Plata, Paseo del Bosque, 1900 La Plata, Argentina;  e-mail: ronderos@museo.fcnym.unlp.edu.ar

ABSTRACT. The larva of Palpomyia guarani Lane, 1946 is described and illustrated by using a phase-contrast and Scanning Electron Microscope, and pupa and adult redescribed by using a phase-contrast stereoscope. Immatures were collected breeding in a tree hole in Bella Vista, Paraguay. Larvae have character states typical of carnivorous larvae. The species is compared with its similar congener Palpomyia columbiana Kieffer, and this record constitutes the first one from Paraguay.

KEY WORDS. Larva. Pupa. Adult. Palpomyia guarani. SEM. Paraguay.

RESUMEN. Se describe e ilustra la larva de Palpomyia guarani Lane, 1946 utilizando Microscopio de Contraste de Fase y Microscopio Electrónico de Barrido. Se redescriben pupa y adulto usando Microscopio de Contraste de Fase. Los estados inmaduros fueron capturados en Bella Vista, Paraguay, en hueco de árbol, donde se desarrollan. La larva presenta características típicas de larvas carnívoras. La especie se cita por primera vez para Paraguay, y es comparada con su similar cogenérica Palpomyia columbiana Kieffer.

PALABRAS CLAVE. Larva. Pupa. Adulto. Palpomyia guarani. MEB. Paraguay.

INTRODUCTION

The cosmopolitan genus Palpomyia Meigen, 1818 includes predaceous midges that are relatively common inhabitants of aquatic and semiaquatic environments (Grogan & Wirth, 1979). Borkent & Wirth (1997), in their world catalog of Ceratopogonidae, listed 234 extant species, of which 75 inhabit the New World. The immature stages of the majority of the species remain unknown, i.e., from the 48 species listed by Borkent & Spinelli (2000) from the Neotropical region, only the larva of one species and the pupae of six are described: Palpomyia armatipes Wirth (larva and pupa, in Grogan & Wirth, 1979), Palpomyia guarani Lane (pupa, in Lane, 1946), Palpomyia lacustris Lane, Forattini & Rabello (pupa, in Lane et al., 1955), Palpomyia linsleyi Wirth (pupa, in Grogan & Wirth, 1979), Palpomyia subaspera (Coquillett) (pupa, in Grogan & Wirth, 1979), and Palpomyia wirthi Lane, Forattini & Rabello (pupa, in Lane et al., 1955).

Palpomyia guarani was originally described by Lane (1946) based on male and female adults and pupa, being the descriptions and illustrations, especially those of the pupa, very incomplete. Subsequently the species has never been mentioned again in the literature except in reference to its original description and/or type-series (Wirth, 1974; Borkent & Wirth, 1997; Borkent & Spinelli, 2000; Felippe-Bauer & de Oliveira, 2001).

During a development of a collecting program of ceratopogonids in the area influenced by the Yacyreta dam lake, in the Parana river between Argentina and Paraguay, we found immatures of P. guarani breeding in a tree hole. The purpose of this paper is to describe the larva and to redescribe the adult and pupa of this species by using Scanning Electron Microscope (SEM), phase-contrast stereoscope and binocular microscope.

MATERIALS AND METHODS

Larvae were collected by using suction pipetae in tree holes and carried to the laboratory in tubes containing water from their natural evironment. They were observed daily for recording pupal development. For the observation of larvae with phase-contrast microscope at oil inmersion, they were slide-mounted in Canada balsam, placed with their ventral side upward to facilitate examination of the epipharynx within the head capsule. Pupae and adults were slide-mounted in Canada balsam, and examined, measured and drawn using binocular microscope with camera lucida. The pinned paratypes in the Entomological collection of the Instituto Oswaldo Cruz, Rio de Janeiro, Brazil were examined using stereo-microscope.

Larva were also examined using Scanning Electron Microscope (SEM) at the Museo de La Plata (JOEL T 100). For that purpose, larvae were prepared following the technique of Ronderos et al. (2000). Terminology follows Huerta et al. (2001) for larvae and pupae, and Downes & Wirth (1981) for adults.

The following measurements and ratios of larvae were taken and/or calculated: head length (HL), head width (HW), subgenal width (SGW), head ratio (HR=HL/HW), mandible length (ML), mandible width (MW), distance between the tips of the lateral arms of the epipharynx (LAW), width of the individual dorsal comb sclerites of epipharynx (DCW), subgenal ratio (SGR=HW/SGW). The following measurements for pupae were taken and/or calculated: total length, operculum length (OL), operculum width (OW), pedicel length, respiratory horn length, pedicel/horn ratio (P/H), operculum length ratio (OW/OL), caudal segment length, caudal segment width.

The studied specimens are deposited in the collection of the Museo de La Plata, Argentina. Paratypes, deposited in the collection do Instituto Oswaldo Cruz, Río de Janeiro, Brazil, were also examined.

RESULTS

Palpomyia guarani Lane, 1946

(Figs. 1-26)

Palpomyia guarani Lane, 1946: 221 (female, male, pupa; Brazil); Wirth, 1974: 54 (in Neotropical catalog); Borkent & Wirth, 1997: 132 (in World catalog); Borkent & Spinelli, 2000: 63 (in Neotropical catalog); Felippe-Bauer & de Oliveira, 2001: 1115 (in list of types IOC).

Description of fourth instar larva (Figfigs13s. 1-13).

Exuvia pale brown. Head capsule (Figs. 1-3) three times longer than broad, apex slightly bent ventrally, chaetotaxy as figured; HL 0.30 (0.32-0.30, n=3) mm; HW 0.21 (0.22-0.20, n=3); SGW 0.11 (n=3); HR 1.43 (1.50-1.36, n=3); SGR 1.93 (2.00-1.80, n=3). Labrum (Figs. 2, 4, 6, LB) not extending beyond hypostoma, longer than wide, with anterolateral sensilla styloconicum; palatum (Fig. 5, PL) with sensillae styloconicum, campaniformia and trichodeum. Messors (Figs. 4-5) thin, gently sclerotized, away from mandibles. Maxilla (Figs. 4, 6-7, MX) with long, cylindrical palpus with three subapical papillae (Figs. 4, 7); galeolacinia (Figs. 4, 7, GL) with upper papilla long, flat, bundle of three stout lower papillae, stout setae thin, long. Mandible (Figs. 4, 7, 10, Mn) hooked, with one strong pointed curved tooth, basal minute one, mandibular pit present, one strong setae in surface, ML 0.04 (n=3) mm; MW 0.01 (n=3) mm. Hypostoma (Figs. 2, 4, 12, HY) finely toothed, medial portion lightly sharp-pointed. Labium small, subtriangular, apex broad. Epipharynx (Fig. 11) gently massive; single comb with a row of 3-4 lanceolate, stout, pointed teeth interrupted by 8-9 shorter ones; small, curved auxiliary sclerites near lateral arms; LAW 0.09 (0.10-0.09, n=3)mm; dorsal comb sclerite wide, semicircular in outer line; DCW 0.03 (0.04-0.03, n=3) mm. Hypopharynx (Fig. 13) long, thin, arms slender.

Thoracic coloration uniformly pale yellowish. Caudal segment (Figs. 8-9) with four pairs of long, stout, caudal setae, two pairs of thiner ones.

Figs. 1-3: Palpomyia guarani Lane, larva. 1. head capsule (laterodorsal view), chaetotaxy; 2. head capsule (ventral view), chaetotaxy; 3. head capsule (laterovental view), chaetotaxy. (ANT) antennae; (LB) labrum; (HY) hypostoma; (x) parantennal setae; (t) prefrontal setae; (z) frontal pits; (s) anterior perifrontal setae; (q) postfrontal setae; (w) anterolateral setae; (u) mesolateral setae; (v) posterolateral setae; (p) posterior perifrontal setae; (o) parahypostomal setae; (y) ventral setae.

Figs. 4-6: Palpomyia guarani Lane, larva. 4-5 head capsule (anteroventral view); 6. head capsule (anterodorsal view). (ANT) antennae; (LB) labrum; (PL) palatum; (Sca) sensilla campaniformia; (SS) sensilla styloconicum; (ST) sensilla trichodeum; (MS) messors; (MP) maxillary palpus; (MX) maxilla; (HY) hypostoma; (GL) galeolacinia; (Mn) mandible.

Figs. 7-9: Palpomyia guarani Lane, larva. 7. (MX) maxilla; (GL) galeolacinia; (MP) maxillary palpus; (Mn) mandible; 8. caudal segment; 9. insertion of setae of caudal segment.

Figs. 10-13: Palpomyia guarani Lane, larva. 10. mandible; 11. epipharynx; 12. hypostoma; 13. hypopharynx (scale = 0.02 mm).

Redescription of pupa (Figs. 14-19)

Female. Length 3.63 (3.93-3.39, n=5) mm. Exuvia pale brown. Cephalotoraxic tubercles (Figs. 14, 16) as follows: anterodorsal tubercle (ad) with two long, subequal, thin setae; dorsolateral tubercle (dl) with two long, subequal setae, one stout, one thin; dorsal tubercles (d) i, ii, iv with long thin seta, iii with long stouter seta, v pore; ventral setae: vm with one very thin seta, vl with two setae, one thin, one very thin. Respiratory horn (Figs. 14, 16) 2.5 times longer than broad, surface bare, apex with 10-12 spiracles; pedicel stout, length 0.04 (0.05-0.03, n=5) mm; length respiratory horn 0.18 (0.19-0.17, n=6) mm; P/H 0.21 (0.27-0.17, n=5). Operculum (Figs. 14-15) 0.5 as long as greatest width, disc covered with small rounded tubercles; posterior margin pointed; two anteromarginal tubercles (am) bearing single long seta, basal sensillum present; OL 0.09 (0.11-0.08, n=4) mm, OW 0.20 (0.21-0.19, n=4) mm, OW/OL 2.08 (2.60-1.80, n=4). Abdominal segments with scattered small spinules. Fourth abdominal segment (Figs. 17-18) with two dorsal anterosubmarginal tubercles (dasm), i with thin seta, ii with stouter seta; four dorsal posteromarginal tubercles (dpm), i,ii on single stout base, i with short, thin seta, ii with long, stout seta, iii pore, iv with minute seta; three ventral posteromarginal tubercles (vpm) with base rounded, seta thin; two lateral posteromarginal tubercles (lpm) with base broad, i with short, thin seta, ii with long, stouter seta; one lateral anterosubmarginal tubercle (lasm) without seta. Caudal segment (Fig.19) length 0.32 (0.39-0.33, n=6) mm, width 0.18 (0.21-0.15, n=6) mm, dorsal surface with abundant posteriorly directed spinules, also present on posterolateral processes.

Male. Length 3.48 mm. Respiratory horn 0.18 mm; pedicel 0.10 mm; P/H 0.55; OL: 0.10 mm, OW 0.20 mm. Caudal segment length 0.31 mm, width 0.19 mm.

Figs. 14-19: Palpomyia guarani Lane, pupa. 14. cephalothorax (lateral view); 15. operculum; 16. respiratory horn; 17. 4th abdominal segment; 18. tubercles of 4^th abdominal segment; 19. female caudal segment (ventral view); (P) pedicel; (RH) respiratory horn; (O) operculum; (ad) anterodorsal tubercle; (vl) ventrolateral setae; (vm) ventromedian setae; (dl) dorsolateral tubercle; (d) dorsal tubercles.

Redescription of adult (Figs. 20-26)

Female (Figs. 20-24).

Head. Dark brown, clypeus slightly paler. Eyes bare, separated by distance equal to diameter of 2.5 ommatidia. Clypeus with 13-15 slender setae. Antenna (Fig. 20) with flagellomeres brown, narrow bases only slightly paler; scape without setae; AR 1.47 (1.56-1.35). Palpus (Fig. 21) elongated; third segment with few scattered sensilla; PR 3.05 (3.22-2.75, n=4). Mandible with 10-12 stout teeth. Thorax. Uniformly dark brown. Scutum with anterior tubercle; three prealar strong setae; double row of three dorsocentral setae. Scutellum with four setae. Legs yellow except coxa, trochanter, femur, basal half of tibia of hind leg dark brown; fore femur swollen, with 10-12 spines; tarsomeres 3- 5 in all legs slightly infuscated; fifth tarsomeres unarmed; hind tarsal ratio 2.50 (2.60-2.30, n=4); claws small, with small basal inner tooth. Wing (Fig. 22) membrane slightly infuscated, anterior veins brown; wing length 1.70 (1.74-1.62, n=4) mm, width 0.55 (0.57-0.54, n=4)mm, CR 0.71 (0.72-0.70, n=4). Halter dark brown. Abdomen. Brown, no trace of gland rods. Sternite 8 (Fig. 24) with anterior portion rectangular, greatly broader than long; posterior portion hyaline, anterolateral margins rounded, heavily sclerotized; two large, prominent setose lobes arising from anterior margin. Sternite 9 (Fig. 24) divided, each arm with slender anteriorly directed portion and broader laterally directed portion. Sternite 10 pale yellowish, with five pairs of large setae; cerci stout. Two rounded, slightly unequal spermathecae with short necks, diameter 0.050 and 0.046 mm, plus rudimentary third (Fig. 23).

Male. Similar to female with usual sexual differences. Wing length 1.32 mm; width 0.42 mm; CR 0.52.

Genitalia (Figs. 25-26). Sternite 9 0.25 times longer than broad, with shallow, irregular posteromedial excavation, ventral surface smooth; tergite 9 tapering distally, cerci lightly sclerotized, bluntly rounded, each one with four setae. Sternite 10 rounded, pilose. Gonocoxite stout, nearly twice as long as broad with setose mesoventral lobe; gonostylus 0.6 times the length of gonocoxite, curved distally, tapering to stout, pointed tip. Aedeagus stout, heavily sclerotized, 1.4 times broader than long; basal arms very short, recurved; basal arch extending 0.25 of total length; distal portion tapering to stout rouded tip; underlying membrane spiculate, with broad rounded tip extending to 0.8 of total length. Parameres (Fig. 26) divided, each with conspicuous, doubly recurved basal arm; stem curved, deeply sclerotized; distal portion stout, nearly straight, tip blunt.

Figs. 20-24: Palpomyia guarani Lane, adult female. 20. antenna; 21. palpus; 22. wing; 23. spermathecae; 24. genital sclerotization.

Figs. 25-26: Palpomyia guarani Lane, adult male. 25. genitalia (parameres removed); 26. parameres.

Distribution. Brazil (São Paulo, Rio de Janeiro, Espirito Santo), Paraguay (Itapua).

Specimens examined. Paraguay, Itapua, Bella Vista, 8-XI- 2000, G. Spinelli, 1 male, 4 females (reared in laboratory), 3 larvae, 1 pupal exuviae male, 6 pupal exuviae female.

For SEM: same locality, 4 larvae.

This is the first record of P. guarani from Paraguay. All the above mentioned specimens were collected in a single, shallow, one meter height tree hole of aproximately 5 cm long and 3 cm width.

Paratypes (pinned): Brazil, Espirito Santo, São Joao, 6-V- 1940, L. Whitman, from bambu, 3 females with pupal exuvia (IOC 360, 361, 362); Brazil, Rio de Janeiro, Distrito Federal, Rio de Janeiro Silvestre, 2-II- 1940, L. Whitman, from tree hole, 1 female (IOC 363); Brazil, São Paulo, Horto Forestal, V-1944, J. Lamosa, 1 female with pupal exuvia (IOC 364)

Discussion

As it was pointed out by Lane (1946) P. guarani is very similar to the colombian species Palpomyia columbiana Kieffer, from which it can be distinguished at the adult stage by the apical fifth of hind femur yellowish and hind tibia dark brown almost to apex in P. columbiana. These differences are itself not very significant, and perhaps P. guarani is a junior synonym of P. columbiana. Unfortunately this pressumption could not be corroborated, because the type of P. columbiana, deposited in the Musée National Hongrois de Budapest, was destroyed by a bombing during the occupation of Hungary by the soviets in 1956. 

The specimens studied were determined as Palpomyia guarani based on the comparison with the original description, as well as with part of the type-series deposited in the Instituto Oswaldo Cruz. We attempted to study the holotype of this species, deposited in the Facultade da Saude Publica da Universidade de São Paulo, but unfortunately it is lost (Maria Anice Sallum, pers. comm.).

The larvae of P. guarani are prognathous, exhibiting an elongate, narrow head, mandible hooked with a single strong tooth, epipharynx gently massive and hypostoma finely toothed, which are character states typical of carnivorous larvae (Thomsen, 1937; Mullen & Hribar, 1988). Apparently, this is the only species of Palpomyia of the world known to breed in tree holes, where microfauna such as copepods were very abundant.

ACKNOWLEDGEMENTS

We would like to acknowledge María Felippe-Bauer and the authorities of the Instituto Oswaldo Cruz for facilities during the recent visit of one of us (MMR) to the Instituto Oswaldo Cruz, where paratypes of P. guarani were studied. Our gratitude also to Maria Anice Sallum from the Coleção Entomológica, Facultade da Saúde Pública da Universidade de São Paulo, for the information on the holotype of P. guarani.

LITERATURE CITED

1. BORKENT, A. & G. R. SPINELLI. 2000. Catalog of the New World biting midges south of the United States of America (Diptera: Ceratopogonidae). Contrib. Entomol. Internat., 4 (1): 1-107.         [ Links ]
2. BORKENT, A. & W. W. WIRTH. 1997. World Species of Biting Midges (Diptera: Ceratopogonidae). Bull. Amer. Mus. Nat. Hist. 233, 257pp.         [ Links ]
3. DOWNES, A. J. & W. W. WIRTH. 1981. Ceratopogonidae. In: McAlpine, J. F. et al. (eds.), Manual of Nearctic Diptera Vol 1, Agric. Canada Monog. 27, Otawa, pp. 393-421.         [ Links ]
4. FELIPPE-BAUER, M. L. & S. J. DE OLIVEIRA. 2001. Lista dos Exemplares Tipos de Ceratopogonidae (Diptera, Nematocera) depositados na Coleção Entomológica do Instituto Oswaldo Cruz, Rio de Janeiro, Brasil. Mem. Inst. Oswaldo Cruz 96 (8): 1109-1119.         [ Links ]
5. GROGAN, W. L. & W. W. WIRTH. 1979. The North American predaceous midges of the genus Palpomyia Meigen (Diptera: Ceratopogonidae). Mem. Entomol. Soc. Wash. 8: 1-125.         [ Links ]
6. HUERTA, H., M. M. RONDEROS & G. R. SPINELLI. 2001. Description of the larva and pupa and redescription of the adult of Culicoides albamaculus Root and Hoffman (Diptera: Ceratopogonidae). Trans. Amer. Entomol. Soc. 127 (4): 545-561.         [ Links ]
7. LANE, J. 1946. Duas Espécies Novas de Ceratopogonídeos Brasileiros. Diptera Ceratopogonidae (Heleidae). Livro de homenagem R. F. d'Almeida 22: 219-226.         [ Links ]
8. LANE, J., O. P. FORATTINI & E. X. RABELLO. 1955. Biologia e espécies novas de Palpomyia e Stilobezzia (Diptera, Nematocera, Ceratopogonidae). Dusenia 6: 81-88.         [ Links ]
9. MEIGEN, J. G. 1818. Systematische Beschreibung der bekannten europäischen zweiflügeligen. Insekten. Vol. 1, xxxvi + 333 pp. Aachen.         [ Links ]
10. MULLEN, G. R. & L. J. HRIBAR. 1988. Biology and feeding behavior of Ceratopogonidae larvae (Diptera: Ceratopogonidae) in North America. Bull. Soc. Vector Ecol. 13 (1): 60-81.         [ Links ]
11. RONDEROS, M. M., G. R. SPINELLI & P. SARMIENTO. 2000. Preparation and Mounting of Biting Midges of the Genus Culicoides Latreille (Diptera: Ceratopogonidae) to be Observed with a Scanning Electron Microscope. Trans. Amer. Entomol. Soc. 126 (1): 125-132.         [ Links ]
12. THOMSEN, L. C. 1937. Part V. Ceratopogonidae. In: Johannsen O. A, Thomsen L. C (eds.), Aquatic Diptera. Parts IV and V. Cornell Univ. Agr. Exp. Sta. Mem. pp. 57-80.         [ Links ]
13. WIRTH, W. W. 1974. Family Ceratopogonidae. A catalog of the Diptera of the Americas south of the United States. Mus. Zool., Univ. Sao Paulo 14: 1- 89.         [ Links ]

Recibido: 17-XI-2003
Aceptado: 25-III-2004