Harbach, Rossi & Harbach, 2008

Rossi, Gustavo C. & Harbach, Ralph E., 2008, Phytotelmatomyia, a new Neotropical subgenus of Culex (Diptera: Culicidae), Zootaxa 1879 (1), pp. 1-17 : 2-14

Culex subgenus Phytotelmatomyia Rossi & Harbach , new subgenus

Type species. Culex renatoi Lane & Ramalho, 1960 . Species included: Culex castroi Casal & García, 1967a , Culex hepperi Casal & García, 1967b , Culex machadoi da Silva Mattos, da Silveira Guedes & Hamilton Xavier, 1978 , and two undescribed species (sp. 1 and sp. 2) from Argentina.

Morphological study revealed a suite of characters that distinguishes this group of species from subgenera Culex and Phenacomyia . The distinctive characters that diagnose this group are listed and compared with homologous characters of subgenera Culex and Phenacomyia in Table 1, and the numbered characters in Table 1 correspond to the numbered arrows on the larval and pupal stages illustrated in Figs. 3–8 . Whereas the larvae and pupae of the group are easily distinguished from the larvae and pupae of Culex and Phenacomyia , the adults are scarcely distinguishable. Despite this, the results of the cladistic analysis (see discussion below) reveal that Phytotelmatomyia is a distinct monophyletic lineage.

Diagnosis. Adults: The scutum has a pattern of pale scales, principally on the margins, which is inconspicuous in Cx. castroi and Cx. machadoi . Females have a patch of pale scales on the maxillary palpus, except in Cx. castroi and Cx. machadoi , which lack pale scales, and a pale patch or band is more or less evident on the proboscis. The tarsi have broad bands across the joints (except in Cx. castroi and Cx. machadoi ). The postgenital lobe of the female genitalia is trapezoidal, at least in Cx. castroi , Cx. hepperi , and the two undescribed species. The male genitalia ( Fig. 2 ) differ from those of Phenacomyia , which have a small hair-like seta f and a nearly straight, short seta h, and are similar to the male genitalia of various Cx. (Cux.) species in having a relatively large, curved seta f and a strong, hooked seta h on the subapical lobe of the gonocoxite. The male genitalia otherwise do not exhibit distinctive characteristics except for the number of teeth on the lateral plate of the phallosome and the number of setae on the ninth tergal lobes.

The principal distinctions of Phytotelmatomyia are found in the immature stages. Larvae: Setae 2–4-A forked or bifid; antenna very short, <0.33 length of head, nearly cylindrical, seta 1-A small with few branches; seta 1-C short, stout, branched or forked; seta 4-C long, reaching anterior margin of head, fan-like, developed similar to 5,7-C; maxilla short, stout, seta 1-Mx inserted 0.60 from base; maxillary brush relatively short, slightly shorter than maxillary body, spiculose area lateral to seta 5-Mx poorly developed; seta 0-P large, inserted posterior to 5-P; seta 3-P multiple branched, short, about 0.33 length of 1-P; seta 4-P similar to 3-P; setae 14-P, 1-M,T and 1-I,II usually with multiple branches; seta 1-I,III multiple branched; seta 7-II long, similar to 7-I; saddle largely covered with spicules that grade into long spicules posteriorly, especially dorsally; ventral brush comprised of 4 pairs of setae. Pupae: Seta 1-CT significantly longer than 2,3-CT; seta 7-II as long as 6-II; seta 5-IV as long as 5-V,VI, about 1.5 length of following tergum; paddle spiculate on anterior 0.4 of surface, with distinct serration posteriorly on margins of inner and outer parts.

Etymology. Phytotelmatomyia is derived from three Greek words: Phyton (n. plant, combining form phyto -); telma, - tos (n. standing water, combining form telmato -), and myia (f. fly). The name is feminine in gender. The three-letter abbreviation Phy. is recommended for the subgeneric name.

Distribution. The species of Phytotelmatomyia are distributed in the Neotropical Region, along the Río Paraná Basin from Brazil to Argentina, including Paraguay and Uruguay. The collection sites of the species are indicated in Fig. 1. This distribution corresponds to the Tupi area of dispersion of Lane (1953). The occurrence of Cx. hepperi in Cosquín, Cordoba Province reported by Brewer et al. (1991) is doubtful.

Bionomics. The daily cycle of activity of Phytotelmatomyia species is unknown. Adults are attracted to humans (see Material examined), but have never been collected inside or outside houses or in CDC light traps (during more than 8,000 hours of trapping in the vicinity of Eryngium plants in Buenos Aires, Entre Ríos, Corrientes, and Misiones Provinces in Argentina, Salto in Uruguay, and Itapua in Paraguay). Only the capture of immature stages is reported previously in published literature. Campos and Lounibos (1999) found Cx. hepperi , Cx. castroi , and Cx. renatoi in two species of Eryngium in Punta Lara, Buenos Aires Province, Argentina, which is concordant with collections made for the present study. Eggs are deposited in small rafts of 4– 8 eggs or as single eggs placed in different axils. Eggs are small but generally resemble the eggs of Cx. (Cux.) species.

Material examined. Specimens included pinned adults reared from fourth-instar larvae collected from the axils of Eryngium species , adult females captured landing on the legs of collectors, dissected male and female genitalia, fourth-instar larvae, and the larval and/or pupal exuviae (of reared adults) mounted on microscope slides in Canada balsam. A total of 605 specimens were examined: 85 M, 89 GM, 65 F, 5 GF, 215 Pe, 122 Le, 2 P, 22 L.

Culex hepperi . 33 M, 30 GM, 13 F, 4 GF, 88 Pe, 44 Le, including holotype, allotype, and paratypes as follow: Argentina, Buenos Aires Province, Zárate , Canal 6 y Paraná de las Palmas River , 1 M (holotype), 8 GM, 1 F, 4 GF, 57 Pe , 30 Le , holotype and paratypes, Casal & García leg , Administración Nacional de Laboratorios de Salud ( ANLIS) " Dr. Carlos G. Malbrán " (formerly Instituto Nacional de Microbiología); Zárate , Talavera Island near Paraná de las Palmas River , 10-03-2004, 1 M, 1 MG, 3 F, 4 Pe, D. Carpintero leg ; same locality, 10-18-2004, 2 M, 2 GM, 5 F, 7 Pe, 4 Le, Rossi leg ; Magdalena, Punta Lara, 2 M, 2 GM, 1 Pe , 1 Le , 10-13- 1987, Rossi leg ; idem, 08-06-1988, 3 M, 3 GM, 1 F, 4 Pe, 2 Le, Rossi & García legs ; same locality, 07-14- 1988, 1 GM, Rossi leg ; idem, 11-02-1988, 4 M, 1 GM, 3 Pe, 1 Le ; same locality, 08-14-1989, 8 M, 8 GM, 1 F, 2 Pe, Campos & Maciá legs ; same locality, 08-28-1989 1 M, 1 GM, Rossi leg ; same locality, 10-23-1989, 1 M, 1 GM, Campos & Maciá legs ; same locality, 08-31-1995, 1 M, 1 GM, Campos leg ; Berisso, Los Talas , 11- 30-1988, 1 M, 1 GM, Rossi leg ; Punta Indio, Balneario Sarandí, 7 M, 1 F, 8 Pe , 4 Le , 04-06-2006, Rossi leg ; Paraguay, Itapua, Encarnación, Quiteria , 10-03-2000, 1 M, 1 GM, 1 F, 2 Pe, 2 Le, López & Ortiz leg.

Culex castroi . 32 M, 41 GM, 31 F, 1 GF, 97 Pe, 56 Le, 2 P, 9 L including holotype and paratypes as follow: Argentina, Buenos Aires Province, Zárate , Canal 6 y Paraná de las Palmas River , 1 M (holotype), 13 GM, 1F, 33 Pe , 16 Le , Casal & García legs, Administracion Nacional de Laboratorios de Salud ( ANLIS) " Dr. Carlos G Malbrán " (formerly Instituto Nacional de Microbiología ); Zárate , Talavera Island , near Paraná de las Palmas River , 03-10-2004, 2 M, 2 GM, 7 F, 1 GF, 10 Pe, 8 Le, D. Carpintero leg ; idem, 18-10-2004, 6 M, 6 GM, 4 F, 9 Pe, 1 P, Rossi leg ; Cañada Honda at Route 9, 03-03-2004, 2 M, 2 GM, 1 F, 3 Pe, 2 Le, Rossi leg ; La Cruz stream at Route 9, 2 M, 2 Pe , 1 Le ; Areco River at Route 9, 6 M, 6 GM, 2 F, 7 Pe , 4 Le , all same date and collector; Los Talas , Berisso , 3 M, 3 GM, 1 F, 2 Pe , 10-30-1988, Rossi leg ; Punta Indio, Balneario Sarandí, 1 M, 1 Pe , 04-06-2006, Rossi leg ; Corrientes Province, Garapé , 09-23-1999, 3 M, 3 GM, 6 F, 8 Pe, 1 P, 9 Le, 2 L, Rossi leg ; Misiones Province, Maní Port, Corpus , 09-17-1999, 1 F, 1 Pe, 1 Le, Pascual leg ; Paraguay, Itapua, Quiteria River , 10-15-1998, 3 L, Spinelli leg ; idem, 10-03-2000, 5 M, 9 F, 15 Pe, 1 P, 13 Le, López & Ortiz legs; Encarnación , Mboy Cae , 10-27-1999, 4 F, 4 Pe, 2 Le, 4 L, Rossi leg ; Uruguay, Salto, 01-03-2001, 1 M, 1 GM, Rossi leg.

Culex renatoi . 7 M, 5 GM, 10 F, 17 Pe, 13 Le, 10 L as follow: Argentina, Buenos Aires, Punta Indio, Balneario Sarandí, 2 M, 2 F, 4 Pe , 2 Le , 04-06-2006, Rossi leg ; Entre Ríos Province, Chajarí , 09-24-1989, 1 F, Balseiro leg ; idem, Ayuí , 12-19-2003, 1 M, 1 GM, 4 F, 5 Pe, 2 L, 5 Le, Rossi leg ; Misiones Province, Santa Ana River at Route 12, 11-16-1999, 4 M, 4 GM, 4 F, 8 Pe, 6 Le, 8 L, Rossi leg.

Culex sp. 1 . 7 M, 7 GM, 3 F, 6 Pe, 2 Le, 1 L as follow: Argentina, Buenos Aires Province, Punta Indio, Villordo stream, 4 M, 4 GM, 3 F, 6 Pe, 2 Le, 1 L, P. Marino leg ; Misiones Province, Santa Ana River and Route 12, 08-13-1999, 3 M, 3 GM, Araki & Pascual legs .

Culex sp. 2 . 6 M, 6 GM, 8 F, 7 Pe, 7 Le, 2 L as follow: Argentina, Corrientes Province, Garapé at Paraná River , 11- 23-1999, 3 M, 3 GM, 4 F, 7 Pe, 7 Le, 2 L, Rossi leg ; Misiones Province, Posadas, Martires Stream , 08-13-1999, 3 M, 3 GM, 4 F, Araki & Pascual legs .

Discussion. The taxonomy of Neotropical mosquitoes of tribe Culicini has changed over the past couple of decades. Harbach and Peyton (1992) introduced Culex subgenus Phenacomyia for Cx. corniger Theobald and two related species, and González Broche and Rodríguez R. (2001) established subgenus Nicaromyia for Cx. nicaroensis Duret. Navarro and Liria (2000) proposed subgeneric status for genus Deinocerites Theobald based on morphological features of larval mouthparts, but this action has not been accepted because it is not supported by the numerous unique characters that distinguish the adults, larvae, and pupae from Culex (Har- bach, 2007). Finally, Tanaka (2003) removed Lutzia Theobald from subgeneric status within Culex and raised it to its original generic rank. As a result of these changes, 14 subgenera are currently recognized within genus Culex in the New World, including: Aedinus Lutz , Allimanta Casal & García , Anoedioporpa Dyar , Belkinomyia Adames & Galindo , Carrollia Lutz , Culex , Melanoconion Theobald , Micraedes Coquillett , Microculex Theobald , Neoculex Dyar , Nicaromyia , Phenacomyia , Phytotelmatomyia , and Tinolestes Coquillett. Of these subgenera, only Culex and Neoculex are widely distributed outside of the Neotropical Region. Culex is by far the largest subgenus, with 201 species (http://mosquito-taxonomic-inventory.info) distributed throughout the world. The subgenus is divided into two principal groups, the Pipiens and Sitiens Groups ( Edwards, 1932) and two smaller groups, the Atriceps and Duttoni Groups ( Belkin, 1962 and Harbach, 1988 , respectively). The New World species are placed in the Pipiens Group, but are not further classified in subordinate groups as are Old World species of the subgenus. The recognition of subgenus Phytotelmatomyia clearly shows that larval characters are more indicative of natural affinities than are the male genitalic characters on which the broad concept of subgenus Culex is principally based.

The analysis of the data set of St. John (2007) with the inclusion of character data for Phytotelmatomyia (Appendix) produced a very different pattern of relationships in the basal part of the cladogram illustrated in Harbach (2007: Fig. 23) that includes subgenera Culex and Phenacomyia . As the purpose of the analysis was to test the monophyly of Phytotelmatomyia , and a discussion of altered relationships is beyond the scope of the present study, only the segment of the cladogram that shows relationships between species of subgenera Culex , Phenacomyia , and Phytotelmatomyia is dealt with here ( Fig. 9 ). Most importantly, Phytotelmatomyia arises from the main stem of the cladogram as a very strongly supported monophyletic group (Bremer support 1.4) interposed between species of subgenera Culex and Phenacomyia . The monophyly of Phytotelmatomyia is supported by a unique combination of seven homoplastic characters (1:0, 22:0, 32:1, 34:2, 39:1, 53:1, 55:1), none of which are listed as diagnostic features in Table 1. Considering all of the data, there is no doubt that Phytotelmatomyia is a distinct lineage that appears to have its closest affinities with subgenera Culex and Phenacomyia .

Fourth-instar larvae of Phytotelmatomyia are readily distinguished from the larvae of the other subgenera of genus Culex . The larvae and pupae exhibit adaptations to specialized habitats – they survive complete desiccation for hours. The larvae of Phytotelmatomyia are capable of moving between leaf axils by sinuous crawling, an uncharacteristic movement of larval mosquitoes that is exhibited elsewhere only in species of Armigeres Theobald , Eretmapodites Edwards , and Trichoprosopon Theobald ( Lounibos, 1983) . The posture of the larvae while resting on substrate is similar to that of Cx. (Microculex) imitator Theobald , with the siphon downward. This resting posture is not frequently observed among species of subgenus Culex . Larval movement is different from the "irregular sustained" movement of Cx. (Cux.) species and the "sinuous fast" movement of Cx. (Phenacomyia) corniger ( Strickman, 1989) .

The adults of Phytotelmatomyia resemble members of the Old World Duttoni and Sitiens Groups in having similar markings on the scutum, proboscis, and tarsi. The male genitalia generally resemble those of members of the Pipiens Group ( Belkin, 1962; Sirivanakarn, 1976; Harbach, 1988 ), and Group B of Lane (1953). Seta 1-C is short and thick as it is in species of the Sitiens Group.

The similarities shared with the larvae of other subgenera of Culex include: short antenna of nearly uniform diameter and seta 1-A reduced as in Carrollia ( Valencia, 1973) , Microculex ( Lane and Whitman, 1951) , and Phenacomyia ; seta 4-C multiple as in Nicaromyia ; seta 3-P multiple branched and short as in Melanoconion ( Sirivanakarn, 1983) and Microculex ; Pecten Row Index (PRI, 0.33 – 0.58) larger than in Cx. (Cux.) (0.31–0.35); PRI and Siphon Index (SI) similar to Phenacomyia (0.37– 0.73 and <4, respectively); saddle with long spicules and larval habitat as in Microculex ; and ventral brush comprised of 4 pairs of setae as in Microculex and Neoculex .

The principal characteristics that distinguish Phytotelmatomyia from the other New World subgenera of Culex include, in larvae: seta 1-C short and thick, branched or forked, seta 0-P large and inserted posterior to 5-P, seta 14-P short and multiple branched, setae 1-M,T and 1-I,II strong and branched, and small PRI and SI; in pupae: long setae 1-CT and 5-IV, and presence of paddle marginal serration posteriorly on inner and outer parts.

Culex hepperi and Cx. castroi are closely related to one another and to Cx. renatoi and Cx. machadoi . With regard to the last species, a detailed study and description would seem necessary to determine whether it is a good species or a synonym of Cx. castroi . The original descriptions should be consulted for detailed information on these species.

Figures

FIGURE 2. Male genitalia of Cx. (Cux.) pipiens, Cx. (Phe.) corniger, and Cx. (Phy.) hepperi.

FIGURE 3. Larva of Cx. (Phy.) hepperi. a–d: Distinct forms of seta 1-C. e,f: Pecten spines of Cx. (Phy.) hepperi and Cx. (Phy.) castroi. g: Spicules on saddle of Cx. (Phy.) renatoi.

FIGURE 4. Pupa and larval maxilla of Cx. (Phy.) hepperi.

FIGURE 9. Topology of relationships between species of subgenera Culex, Phenacomyia, and Phytotelmatomyia obtained when character data for three species of the last taxon (Cx. castroi, Cx. hepperi, Cx. renatoi) are included in the data set of St. John (2007), and the data are analyzed using implied weights, implemented by PIWE, with the default value of K = 3.