Redescription of Culex(Culex)brethesiDyar, 1919 (Diptera: Culicidae)

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Accepted by G. Courtney: 21 Aug. 2006; published: 11 Sept. 2006 25

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ISSN 1175-5334 (online edition)Copyright © 2006 Magnolia Press

Zootaxa 1312: 25–35 (2006) www.mapress.com/zootaxa/

Redescription of Culex (Culex) brethesi Dyar, 1919 (Diptera: Culicidae)

ROSSI, GUSTAVO C.Centro de Estudios Parasitológicos y de Vectores (CEPAVE) 2N° 584, B1902CHX La Plata, Argentina. E-mail [email protected]

Abstract

Culex (Culex) brethesi Dyar is redescribed in the adult, pupal and fourth-instars larvae and the malegenitalia. The paper includes available information on the taxonomy and distribution of the species.The taxonomy and identification of Cx. brethesi are reviewed in light of current knowledge of thesubgenus Culex.

Key words: Diptera, Culicidae, Culex brethesi, male, female, larva, pupa, Argentina

Introduction

Culex (Culex) brethesi was named by Dyar (1919) based on the male genitalia of Culexlynchii Bréthès, 1912 (illustrated by Bréthès, 1916), a junior synonym of Aedes crinifer(Theobald, 1903). The first brief description of the species appeared in Dyar (1928).Edwards (1932) listed brethesi in the salinarius-apicinus section and suggested thepossibility that it was the same species known as Cx. dolosus (Lynch Arribalzaga, 1891).Culex brethesi was synonymized with Cx. inflictus Theobald, 1901 by Lane (1953),without explanation. Duret (1953) mentioned the presence, in his collection, of the firstknown male of Cx. brethesi from Buenos Aires Province. Bachmann and Casal (1962)compared the genitalia of Cx. brethesi with those of Cx. inflictus and stated that Duret(1953) validated this synonymy of these nominal species by Lane (1953). Duret (1953)however, did not mention this. Bachmann and Casal (1962) also presented a briefdescription of the pupal and larval stages. Forattini (1965) followed Bachmann and Casal’sdescription of the pupa and larva, and misunderstood the description of the adultscharacterized as "tromba escura", "tergites abdominais escuros com faixas basais deescamas brancas", and “ditistilo com fina anelaHao na extremidade distal”. The descriptionof Culex brethesi by Bram (1967), and the characters used to identify this species in his

ROSSI, GUSTAVO C.26 © 2006 Magnolia Press

1312ZOOTAXA key, disagreed with the corresponding figure of this species. Since the only reliable

treatments of Culex brethesi is the brief description of the adult by Dyar (1928) and thepupal and larval stages by Bachmann and Casal (1962), the purpose of this paper is toprovide a more detailed description of the male, female, pupa and fourth-instars larva.Most of the specimens used in this study were collected as larvae and pupae and reared toadults in the laboratory. Collections were made in Punta Lara, City Bell, Romero andZarate in Buenos Aires Province. Other specimens are deposited in the La Plata Museumcollection. The morphological terminology follows Harbach and Knight (1980), theabbreviations for genera and subgenera are from Reinert (2001).

Culex (Culex) brethesi Dyar, 1919

Previous usage: Culex lynchii Bréthès, 1912, female; Bréthès, 1916, male (not female); Bachmann& Casal, 1962, male, larva, pupa; in part of Bram, 1967.

Culex (Culex) brethesi of Dyar, 1928, male, female.Culex (Culex) inflictus in part of Lane, 1953.

FEMALE: (Range of branches based on 8 reared females). Head: integument dark brown.Vertex and occiput with narrow, curved decumbent pearly scales medially, broader andwhitish laterally and denser, forked scales black. Clypeus dark brown, bare. Proboscislonger than forefemur, dark-scaled but scales on underside paler from near base to distal0.2. Maxillary palpus 0.17 length of proboscis, palpomere 3 dark-scaled. Antennasubequal to proboscis in length, pedicel brown. Thorax: scutal integument dark brown,setae dark. Scutal scales small, fine, golden, somewhat larger on scutal fossa and supraalarareas. Scutellar integument moderate brown. Scutellar setae strong, long, 8 on mid lobeand 6 each in lateral lobe. Scutellar scales same as scutal fossal scales. Paratergite bare.Antepronotum: light brown, 8–10 large setae, 2–5 small setae and few scales. Pleuralintegument whitish. Pleural setae dark, numbers as follows: 12 (9–15) proepisternal, 2–4prealar, 2 upper mesokatepisternal, 2–5 lower mesokatepisternal, 1 prominent lowermesepimeral, 9–12 upper mesepimeral. Pleural scales in whitish patches on lower andupper mesokatepisternal and small patch before upper mesepimeral setae. Without prealarand postspiracular scales. Legs: coxae and trochanters with scales on lateral surface.Femora darkscaled except for line of light scales on anterior surface from base to nearapex; tibiae dark-scaled with white scales at apex and base; tarsi dark-scaled. Wings: dark-scaled, costa with pale scales from base to level of humeral crossvein. Halter: stem light,apex and knob dark-scaled. Abdomen: terga mainly black-scaled; tergum I setose, withoutscales; terga II, VIII with traces of basal white bands, with posterolateral triangular patchof white scales extending basally, these spots united to inconspicuous basal pale bandswhen present. Sternum II with white scales, III to VIII with dark scales and median andposterior patches of white scales.

MALE: Holotype male mounted on a microscope slide with a female, labeled: "Culex

© 2006 Magnolia Press 27CULEX (CULEX) BRETHESI

1312ZOOTAXALynchii Brethes" (handwritten in ink) and “Holotipo Culex (Culex) brethesi 364, Dyar,

1919; 1966 Casal” (handwritten in pencil). On the other side: “Holotypus” and “Dipt. 62”on separate labels. This information appears in Belkin et al. (1968). The holotype isdeposited in the Buenos Aires Museum (Fig. 2 a, b, c). Head: as described for femaleexcept for sexual differences. Proboscis dark-scaled except from base to apex ventrally.Maxillary palpus exceeding length of proboscis by length of two distal palpomeres; basesof palpomeres 3, 4 and 5 and apices of 3 and 5 with spot of white scales, and 4 with smallline apically. Abdomen: terga with traces of narrow basal white bands, basolateral spotsdistinct. Genitalia (Fig. 1): Ninth tergal lobes small, each with 9–19 setae in 2 or 3irregular rows (Fig. 3 d). Gonocoxite (Fig. 1 a, b, Fig. 2 c) normal, with 10-16 stronglydeveloped ventrolateral setae. Subapical lobe undivided, gonostylus stout, curved andnarrowed distally, with 2 small slender setae near apex of concave surface. Gonostylarclaw short, trough-like. Subapical lobe of gonostylus prominent, undivided, setae a–c andg in row on apex, setae f and h at level of g on mesal and lateral sides of lobe respectively,setae a rod-like and pointed, b and c with hooked apices, g foliform, asymmetrical, f short,and h slightly curved distally. Phallosome (Fig. 1 c, d, e, Fig. 3 c): lateral plate small with1-3 small teeth, small lateral lobe flat, continuous with base of thumb-like dorsal process.Ventral arm straight dorsomesad, dorsal surface somewhat convex, longer than teeth,dorsal arm V-shaped medially. Paraproct with long, curved basal lateral arm andconspicuous ventral acetabulum, with lobe-like appearance near paraproct crown, crowndark with numerous needle-like spicules, basal lateral arm with 2–5 cercal setae. Seta f ofthe holotype is very short. In 10 of 36 male genitalia examined, seta f was minute (Fig. 2c), in 14 other it was represented by one alveolus and in another 12 it was not visible.

PUPA: Placement and character of setae as in Fig. 3, range and modal number ofbranches in Table 1. Cephalothorax: Lightly tanned, metanotum and legs darker, setae 1,2-9-CT usually triple, 3,5-12-CT usually with 4 branches, 10-CT usually with 9 branches(4–11), 11-CT usually double (90%) (2,3). Trumpet: tanned, almost cylindrical, index 5.50(4.18–6.43) tracheoid area darker, about 0.3 from base. Abdomen: lightly tanned, posteriorarea of tergum I and anterior margin of other terga darker, particularly terga II-VII; lengthabout 3.3 mm. Seta 1-I with 6–8 primary branches, 1-II with 9–20 branches, 1-III usually 6branches, setae 2-I, 10-IV, 11-V,VII and 7-VII usually single (90%). Genital lobe: lightlytanned in both sexes, length 0.20 mm in female, 0.39 mm in male. Paddle: lightly tanned,midrib distinct except at apex; 2 setae present 1-Pa larger, single or double with distinctalveolus, 2-Pa shorter, single, without distinct alveolus. The positions of these setaerelative to each other are quite variable.


1312ZOOTAXA TABLE 1. Number of branches for pupal setae of Culex (Culex) brethesi Dyar a.

a Based on counts from 10 specimens.b Number of primary branches Mode in parenthesis.

LARVA: Placement and character of setae as in Fig 4, range and modal number ofbranches in Table 2. Head: lightly tanned, darker areas of antennal prominence, compoundeye and dorsal apotome. Collar moderately developed along lateralia, tanned.Dorsomentum with 5–7 teeth on either side of median tooth. Seta 1-C slender, 2-C absent,3,4-C single, 5-7-C strongly developed, 5-C usually 5 branched (3–7), 6-C usually triple(3–6), 7-C with 5–10 branches. Antenna: length 0.64–0.74 mm, range 0.66 mm. lightlytanned, darker distally; seta 1-A with 18–28 (mode 21) aciculate branches. Thorax:integument hyaline, covered with tiny spicules (near 5 µm), tubercles of all large setaetanned, tubercles of setae 9-12-P, M with moderately large spine. Setae 1-3, 6-P single,4,7-P double, 8-P usually with 1-4 branches, 11-P with 3–5 branches. Seta 1-M usuallywith 1–5 branches, larger than 3-M; 3-M usually single. Setae 1,2-T of similar length.

SetaNumber CT I II III IV V VI VII VIII IX P

0 - - 1 1 1 1 1 1 1 - -

1 24 (3) 68 (7)b 4-10 (8)

920 (17) 4-8 (7) 27 (6) 3-7 (4) 1-6 (3) - 1 1,2 (1)

2 24 (3) 15 (1) 90%

1 1 1 1 1 1 - - 1

3 37 (4) 13 (2) 80%

2 1,2 (2) 26 (3) 2 13 (2) 2,3 (3) 90%

- - -

4 27 (3) 13 (2) 17 (4) 26 (4) 14 (3) 27 (3) 1,2 (2) 27 (2) 80%

1-4 (2) - -

5 2-6 (4) 17 (6) 46 (4) 2-8 (6) 27 (3) 2 15 (2) 2-6 (2) 80%

- - -

6 24 (2) 1 1 2-6 (4) 36 (3) 26 (5) 2-8 (5) 2,3 (3) - - -

7 24 (2) 1,2 (1) 1,2 (1) 1-4 (3) 17 (3) 17 (1) 1 1,2 (1) 90%

- - -

8 3-7 (6) - - 1-6 (1) 1,2 (2) 1-4 (2) 1,2 (1) 14 (3) - - -

9 1 1 1 1 1 1 1 2-6(4) 618 (8) - -

10 411 (9) - - 1,2 (2) 1,2 (1) 90%

1 1 1 - - -

11 1,2 (2) 90%

1 - 1 1 1,2 (1) 1 1,2 (1) - - -

12 27(4) - - - - - - - - - -

13 - - - - - - - - - - -

14 - - - 1 1 1 1 1 1 - -


1312ZOOTAXAAbdomen: integument hyaline, spiculation present but finer than on thorax, more evident

on segment VIII. Tubercles of setae 6-I,VI, 7-I and 1-3-VIII moderately tanned. Seta 1-II-VI double, 1-I with 5–11 branches. Segment VIII: comb with 34–44 scales arranged in 3 or4 irregular rows, scales normally fringed on sides and apex. Seta 1-VIII with 7–9 branches,3-VIII with 8–12 branches, 5-VIII with 3–7 branches. Siphon: tanned; pecten on basal 0.3of siphon, with 11–17 large scales each with 1-3 basal denticles; index 3.79–4.91, mean4.35. Seta 1-S in six pairs, 1a-S inserted near most distal pecten spine, 1e-S out of line.Segment X: saddle complete, tanned, with distinct spicules on posterolateral end; length0.44–0.50 mm, range 0.46 mm. Seta 1-X usually double (2,3), 2-X usually double (2,3),ventral brush (seta 4-X) with 6 pairs of setae.

FIGURE 1. Male genitalia structures of Culex brethesi. a, b : Gonocoxite; c: Lateral plate in dorsal

view; d: Lateral plate in ventral view; e: Lateral plate of the holotype of Cx. brethesi.


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FIGURE 2. Holotype of Culex brethesi: a: Microscope slide bearing the holotype (the lowerspecimen); b: Genitalia; c: Detail of the gonocoxite.


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FIGURE 3. Pupa of Culex brethesi. a): Cephalothorax, CT; b): Metathorax and abdomen, left side= dorsal, right side = ventral; and male genitalia structures of Cx. brethesi; c): Lateral plate ofgenitalia; d): Ninth tergum of genitalia.


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FIGURE 4. Larva of Cx. brethesi, a): Thorax and abdominal segments I-VI; left side = dorsal, rightside = ventral; b): Head; left side = dorsal, right side = ventral. Pecten (PS); comb scale (CS); c):Abdominal segments VII-X, side view.


1312ZOOTAXAMaterial examined: Culex brethesi: 40 %, 41 % G, 30 &, 45 Pe, 8 P, 25 Le, 9 L, as

follows: Argentina: Buenos Aires Province, San Isidro 1 % holotype Bréthès leg. MACN;

Zarate 3-X-1998, 12 %, 12 % G, 5 &, 8 Pe, 2 L, 13 Le, Spinelli leg.; same locality Route 9

km 109 3-III-2004, 1 %, 1 % G, 5 &, 6 Pe, 4 Le Rossi leg.; Tandil, Airport, 13-X-2001 1 %,

1 % G, G. Marti leg.; Brandzen, Route 215 km, 25, 22-III-1989, 1 %, 1 % G, GarcRa-Rossi

leg.; La Plata, City Bell, 27-IX-1987, 7 %, 7 % G, 2 Pe, 1 Le, Rossi leg.; La Plata, Romero,

April, 1996, 3 &, 2 Pe, 6 Le; 24-V-1996, 1 Pe, 2 L, 2 Le; Jun., 1996, 1 %, 1% G, 1 Pe, 1 Le;

17-VIII-2001, 1 %, 1 % G, 1 Pe, 1 Le; 26-VIII-2001, 2 %, 2 % G, 2 Pe, 1 L, 4 Le, all J. J.

Garcia leg.; idem, 2 %, 2% G, 3 &, 5 Pe, 5 Le, 6-VII-2005; idem, 2 %, 2 % G, 6 &, 12 Pe, 9

Le, 2 L, 28-IV-2005, all V. Micieli leg.; Ensenada, Punta Lara, Boca Cerrada, 25-IX-1989,

4 %, 4 % G, 4 &, 3 Pe, 2 L, Campos-Maciá leg. Entre RRos Province, Chajari, Camping

Drewars, 1 % G, 1 &, 1 Pe, R. Ronderos leg.; Corrientes Province, Villa Olivari, 16-VIII-

1995, with CDC light trap, 2 %, 2 % G, Rossi leg.; Posadas, Misiones Province, 3 %, 3 % G,

3 Pe, Rossi leg. All specimens are deposited in the La Plata Museum.

Comments: The positions of the paddle setae are variable, as shown in Fig.3b. Tanaka(2004) made a similar observation for species of Culex from Japan. Tanaka designed thelonger seta with an alveolus as seta 1-Pd and the shorter one without a visible alveolus asseta 2-Pd. In this work these setae are designated setae 1-Pa and 2-Pa, respectively, inaccordance with more recent workers.

Distribution: Culex brethesi is known from the provinces of Buenos Aires, Cordoba,Mendoza, Misiones, Santa Fe and Santiago del Estero, all confirmed by dissection of malegenitalia (Bachmann & Casal, 1962), Entre Rios Province (Rossi, 1995), CorrientesProvince (Rossi et al., 2002), and Misiones Province (this report). Other records of thisspecies not based on dissected male genitalia are dubious.

Systematics: Culex brethesi larvae were collected in ponds or pools with or withoutgrass. In some specimens were collected in association with larvae of Cx. dolosus and Cx.maxi Dyar, 1928. The presence of pale scales at the base of the costa in adults of Cx.brethesi is a characteristic of several species in South America, including Cx. apicinusPhillipi, 1865, Cx. fernandezi Casal, GarcRa & Cavallieri, 1966, Cx. lahillei Bachman &Casal, 1962, Cx. maxi and Cx. paramaxi Duret, 1968. The characteristics that separate Cx.brethesi from these species include: tarsi and abdominal segments with white bands in Cx.maxi; abdominal terga with white bands in Cx. fernandezi; postspiracular scales in Cx.lahillei; scutum with pattern of pale scales in Cx. apicinus; and Cx. paramaxi is knownonly in the type locality. The male is distinguished by the genitalia. The reduction of themesosome is similar to Cx. acharistus Root, 1927, but this species has seta f hooked. Themajority of pupae of the species of Culex (Culex) are extremely similar and very difficultto differentiate. The fourth-instars larva of Cx. brethesi is very similar to Cx. dolosus (s.l)and Cx. eduardoi Casal & Garcia. It is possible to distinguish Cx. dolosus by the largerspicules and smaller length of the saddle, and Cx. eduardoi by the larger siphonal index,larger number of comb scales and absence of spicules in abdominal segments I–VI.


1312ZOOTAXA TABLE 2. Number of branches for setae of the fouth-instar larvae of Culex (Culex) brethesi Dyar.a

Head Thorax Abdominal segments

a Based on counts from 10 specimens.Mode in parenthesis.

SetaNumber C P M T I II III IV V VI VII VIII X

0 - 48 (8) - - - 1 1 1 1 1 1 1 -

1 1 1 15 (4)

35 (4) 511 (7)

46 (4)

46 (4)

3-5 (4)

3,4 (4)

2-4 (4)

4,5 (5)

79 (8)

2,3 (2)

2 - 1 2,3 (2)

1,2 (1)

1,2 (1)

1,2 (1)

1,2 (1)

1 1 1 1,2 (1)

1 2,3 (2)

3 - 1 1 47 (4) 2,3 (2)

1,2 (2)

13 (1)

1,2 (1)

1 1-3 (1)

1,2 (1)

812 (9)

1

4 1 2 24 (2)

3-6 (4)

913 (11)

49 (7)

1-3 (1)

1-3 (2)

47 (5)

35 (4)

1,2 (1)

37 (7)

5,6 (6)

5 38 (7)

1 14 (1)

1,2 (1)

25 (3)

24 (3)

2-5 (3)

35 (3)

2,3 (3)

24 (3)

24 (4)

- -

6 36 (3)

1 1 1,2 (1)

3 3 2 2 2 2 > 16 - -

7 510 (7)

2 1 69 (9) 2 49 (5)

310 (8)

69 (7)

512 (10)

1 1Siphon

8 26 (4)

2 58 (5)

48 (5) - 1 1,2 (1)

1,2 (1)

2 13 (2)

58 (8)

1a-S 48 (6)

9 38 (6)

1 36 (4)

47 (5) 2 1 1,2 (1)

1 1,2 (2)

1 35 (4)

1b-S 38 (6)

10 2,3 (2)

1 1 1 1 1 1 1 1 1 1 1c-S 59 (6)

11 24 (2)

35 (3) 24 (3)

15 (4) 49 (5)

25 (3)

1,2 (2)

13 (1)

13 (2)

15 (4)

1,2 (2)

1d-S 59 (6)

12 35 (3)

1 1 1 13 (1)

14 (3)

13 (1)

1-3 (2)

13 (1)

1 1-3 (1)

1e-S 35(4)

13 2,3 (3)

- > 11 48 (5) 13 (2)

> 30 35 (4)

4,5 (4)

46 (4)

> 50 35 (3)

1f-S 35 (4)

14 1,2 (1)

1 - - - 1 1 1 1 1 1

15 27 (5)

- - - - - - - - - -

16 - - - - - - - - - - -

17 - - - - - - - - - - - - -


1312ZOOTAXAAcknowledgement

To Dr. W. R. Almirón for your comments and Dr. R. E. Harbach for your help in revisingthe manuscript.

References

Bachmann, A.O. & Casal, O.H. (1962) Notas sobre Culex (Culex) argentinos (Diptera: Culicidae).Anales del Instituto Nacional de MicrobiologRa, 1, 77– 81.

Belkin, J.N., Schick, R.X. & Heinemann, S.J. (1968) Mosquito studies. (Diptera: Culicidae) XI.Mosquitoes originally described from Argentina, Bolivia, Chile, Paraguay, Peru and Uruguay.Contribution of American Entomologist Institute, 4, 1, 9–29.

Bram, R.A. (1967) Classification of Culex subgenus Culex in the New World (Diptera: Culicidae).Procedings United States Natural Museum, 120, 3557, 1–122.

Bréthès, J. (1916) Algunas notas sobre mosquitos argentinos. Anales del Museo Nacional, BuenosAires, 28, 193–218.

Duret, J.P. (1953) Notas sobre Culex argentinos. (Diptera: Culicidae). Revista de la Sanidad MilitarArgentina, 52, 2, 272–278.

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Dyar, H.G. (1928) The Mosquitoes of the Americas, Pub. N° 387 Carnegie Institution Washington.616 pp.

Edwards, F.W. 1932 Diptera, Family Culicidae, In: P. Wytsman, Genera Insectorum, Brussels. Fas-cicle 194, 258 pp.

Forattini, O.P. 1965 EntomologRa MJdica. Vol. 2. Culicini: Culex, Aedes e Psorophora, Universityof Sao Paulo. 506 pp.

Harbach, R.E. & Knight, K.L. (1980) Taxonomists’ Glossary of Mosquito Anatomy. Plexus Publish-ing, Inc., Marlton, New Jersey. xi + 415 pp.

Lane, J. (1953) Neotropical Culicidae, Vol. 1 University of Sao Paulo. 548 pp.Reinert, J.F. (2001) Revised list of abbreviations for genera and subgenera of Culicidae (Diptera)

and notes on generic and subgeneric changes. Journal American Mosquito Control Associa-tion, 17, 1, 51–55.

Rossi, G.C. (1995) Culicidos nuevos para las provincias de Entre RRos y Corrientes. RevistaSociedad Entomológica Argentina, 54, 1–4, 97–98.

Rossi, G.C., Pascual, N.T. & Krsticevic, F.J. (2002) Mosquitos (Diptera: Culicidae) en el área deinfluencia de la Represa de Yacyretá, Argentina. Neotrópica, 48, 23–35.

Tanaka, K. (2004) Studies on the pupal mosquitoes of Japan (10) Culex (Culex) (Diptera: Culi-cidae). Japan Journal Systematic Entomology, 10, 1, 9–42.

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Redescription of Culex(Culex)brethesiDyar, 1919 (Diptera: Culicidae)