DISSIDENS, Taai & Harbach, 2015

Taai, Kritsana & Harbach, Ralph E., 2015, Systematics of the Anopheles barbirostris species complex (Diptera: Culicidae: Anophelinae) in Thailand, Zoological Journal of the Linnean Society 174 (2), pp. 244-264 : 253-256

ANOPHELES ( ANOPHELES ) DISSIDENS SP. NOV.

Anopheles (Anopheles) barbirostris in part of Reid, 1962 ( Thailand, ♀ * ♂ E* L P*, taxonomy); Harrison & Scanlon, 1975 ( Thailand, ♀ * ♂ * L* P*, taxonomy); Reid et al., 1979 ( Thailand, ♀ L P morphology).

Anopheles barbirostris in part (?) of Harrison et al., 1988 ( Thailand, A L P morphology).

Anopheles barbirostris forms A (in part), B (in part), and C of Baimai et al., 1995 ( Thailand, metaphase karyotypes).

Anopheles barbirostris Form A in part of Saeung et al., 2007 ( Thailand, mitotic karyotype, cross-matings, COI and COII mtDNA, ITS2 rDNA).

Anopheles barbirostris species A1 of Saeung et al., 2008 ( Thailand, mitotic karyotype, cross-matings, COI and COII mtDNA, ITS2 rDNA); Suwannamit et al., 2009 ( Thailand, cross-matings, metaphase karyotype, COI and COII mtDNA, ITS2 rDNA); Thongsahuan et al., 2011 ( Thailand, Plasmodium susceptibility); Otsuka, 2011 ( Thailand, ITS2 rDNA).

Anopheles barbirostris Clade III of Paredes-Esquivel et al., 2009 ( Thailand, COI mtDNA, ITS2 rDNA); Paredes-Esquivel & Townson, 2014 (Sumatran Indonesia, Thailand, ITS2 rDNA).

Diagnosis

Anopheles dissidens closely resembles but is generally smaller than other members of the Barbirostris Complex. Sequences for COI and ITS2 are diagnostic and reliably distinguish An. dissidens from other members of the Barbirostris Complex, including the very closely related An. vanderwulpi (see below). Some potentially differential morphological features are denoted below, but for practical purposes An. dissidens is morphologically indistinguishable from other species of the complex.

Description

Female

Distinctly smaller than An. barbirostris , as indicated by measurements of anatomical features listed in Table 1: lengths of proboscis, maxillary palpus, antennal flagellum, wing, vein R 4+5, and forefemur statistically significantly shorter ( Table S2). Lower mesokatepisternal setae (zero to four) and upper mesepimeral setae (five to seven) usually less numerous than in An. barbirostris ( Table 1); apical pale band of hindtarsomere 3 0.06– 0.12 mm (mean 0.07 mm), extended across joint onto base of hindtarsomere 4 in 10% of females examined.

Male

As for An. barbirostris except generally smaller, as indicated by measurements of the gonocoxite, distal parabasal setae, internal seta, gonostylus, claspette club, and aedeagus listed in Table 2: lengths of claspette, claspette club, and aedeagus statistically significantly shorter ( Table S3).

Pupa

As described for An. barbirostris ; setal branching in Table S6; branching of seta 2 compared with other species of the complex in Table 3; differences include seta 2-V with one to three branches; sum of branches of pair of seta 12-CT = 4–7 (6, 7), pair of seta 3-III = 5– 12 (7).

Larva, fourth instar

As described for An. barbirostris ; setal branching in Table S7; differing in having seta 13-M with two to eight (three) branches; seta 8-S with three to eight (four) branches.

Mitotic karyotype

Three types of X chromosome (X 1, X 2, X 3) and four types of Y chromosome (Y 1, Y 2, Y 3, Y 4) comprising four karyotypic forms (X 1 X 2 X 3 Y 1, X 1 X 2 X 3 Y 2, X 2 X 3 Y 3, X 2 Y 4) have been identified in the early fourth-instar larval brains of An. dissidens ( Baimai et al., 1995; Saeung et al., 2007; Suwannamit et al., 2009).

Cross-matings

Reciprocal cross-matings between An. dissidens (as An. barbirostris species A1) and An. saeungae (as species A2) were conducted by Saeung et al. (2008). Only 21% (A 1♀ × A 2♂) and 13% (A 2♀ × A 1♂) of the eggs laid by the females gave rise to F 1 adults, with distorted sex ratios, abnormal ovarian follicles in females, and atrophied accessory glands and testes in males. Additionally, the salivary gland polytene chromosomes of the F 1 larvae exhibited partial asynapsis, particularly at the free ends of the chromosome arms. Suwannamit et al. (2009) obtained similar results from cross-matings between An. dissidens (as species A1) and An. barbirostris (as species A4).

DNA sequence

Specimens identified as An. dissidens are shown in Table S1, together with GenBank accession numbers for ITS2 and COI sequences. The ITS2 subunit for An. dissidens yields a dominant product of 1822 bp. The four interspecifically variable sites at bases 154, 346, 376, and 469 that are unique for the COI gene of An. dissidens are shown in Figure 4 . The results of Bayesian analyses of ITS2 and COI sequences are shown in Figures 5 and 6 , respectively. Both trees show that An. dissidens is distinct from the other species of the Barbirostris Complex. Our ITS2 sequences for An. dissidens (A1) fall within a strongly supported clade ( Fig. 5 , BPP 100%) with two sequences (th39.3 and bsk33) of An. barbirostris Clade III of Paredes-Esquivel et al. (2009).

Bionomics

Anopheles dissidens occurs in hilly country. Like all other species of the Barbirostris Complex, the immature stages of An. dissidens probably occur in stagnant or slowly running bodies of fresh water with vegetation, e.g. rice fields and associated waterways. Adult females are mainly zoophilic. Adults have been frequently collected in traps baited with water buffalo. Thongsahuan et al. (2011) found that 9.09% of females (as An. barbirostris species A1) were capable of developing sporozoites of P. vivax during experimental infection studies.

Distribution

Based on COI, COII, and ITS2 sequences, An. dissidens is currently only definitely known to occur in Thailand (Chiang Mai, Mae Hong Son, Sa Kaeo, Tak, and Trat Provinces; Saeung et al., 2008; Paredes-Esquivel et al., 2009; present study).

Etymology

The specific name is taken from the Latin adjective dissidens , meaning differing or disagreeing, in reference to the sister relationship of the species with An. vanderwulpi Townson & Harbach (see below).

Type series

Two-hundred and twenty-six specimens (115 ♀, 65 ♂, 11 Le, 11 Pe, 24 L) derived from 13 molecularly identified progeny broods: A1(1)–A1(11), A1(13), and A1(14). Holotype, ♀ [A1(1)-6], with Le and Pe on microscope slide, offspring of female collected as follows: THAI- LAND , Chiang Mai Province, Chiang Dao District, Ban Wang Jom , buffalo-baited trap, 23.xi.2013, coll. Choochote et al. Paratypes, same data as holotype: 6 ♀ LePe [A1(1)-2 to -4 and -9 to -11]; 108 ♀ [A1(2)-1, -2, -5 to -12; A1(3)-1 to -5, -8, -9; A1(4)-1, -3, -4, -6, -8 to -10; A1(5)-2, -4, -6; A1(6)-1, -5, -8, -9; A1(7)-1, -2, -4 to -12; A1(8)-1 to -7; A1(9)-2 to -4, -6 to -11; A1(10)-4 to -13; A1(11)-16 to -30; A1(13)-5, -7, -13 to -21; A1(14)- 5, -8, -17, -18, -20 to -30]; 4 ♂ LePe [A1(1)-1, -5, -7, -8]; 61 ♂ [A1(2)-3, -4; A1(3)-6, -7; A1(4)-2, -5,-7; A1(5)- 1, -3, -5; A1(6)-2 to -4, -6, -7; A1(7)-3; A1(9)-1, -5; A1(10)-1 to -3; A1(11)-1 to -15; A1(13)-1 to -4, -6, -8 to -12; A1(14)-1 to -4, -6, -7, -9 to -16, -19]; 24 L [A1(1)-A, -B; A1(2)-A, -B; A1(3)-A, -B; A1(4)-A, -B; A1(5)-A, -B; A1(6)-A, -B; A1(7)-A, -B; A1(8)-A, -B; A1(10)-A, -B; A1(11)-A, -B; A1(13)-A, -B; A1(14)-A, -B]. The type series is deposited in BMNH .

Figures

Figure 4. Alignment of the polymorphic sites along a 658-bp fragment of the mitochondrial cytochrome c oxidase subunit I gene in Anopheles barbirostris (one female), Anopheles dissidens sp. nov. (13 females), Anopheles saeungae sp. nov. (nine females), Anopheles wejchoochotei sp. nov. (six females), and An. barbirostris species A3 (three females) (Saeung et al., 2008). Codes for the specimens are shown in Table S1. Bases enclosed in boxes represent species-specific differences among the five species.

Figure 5. Bayesian consensus tree for internal transcribed spacer 2 sequences. The tree is rooted on Anopheles (Cellia) dirus. Only Bayesian posterior probabilities greater than 50% are shown on the branches. The bar represents 0.1 substitutions per site.

Figure 6. Bayesian consensus tree for cytochrome c oxidase subunit I sequences. Only Bayesian posterior probabilities greater than 50% are shown on the branches. The bar represents 0.01 substitutions per site.