Toxorhynchites (Lynchiella) caatingensis, Andrade & Corte, 2021

Andrade, David Campos & Corte, Roseli La, 2021, Toxorhynchites (Lynchiella) caatingensis sp. nov. (Diptera: Culicidae) from the semi-arid region of Brazil, Zootaxa 5072 (2), pp. 130-144 : 132-134

Toxorhynchites (Lynchiella) caatingensis , sp. nov.

LSID: urn:lsid:zoobank.org:pub:72908E7C-78C0-4C07-810F-71ED07E00959

Adult female ( Figs 1 , 2 ). Head: Occiput covered with metallic blue scales with violet sheen, golden laterally; ocular line with 6 light brown scales; 14–16 erect short brown scales in postoccipital area. Antenna with flagellomere 1 covered with dark scales; integument of pedicel, clypeus and frons dark with white pruinosity. Proboscis long, length 4.8 mm, gradually attenuated towards apex, abruptly curved downward, scales with metallic sheen, mainly golden with blue, green and violet accents, except at base; labellum with scales and short setae. Maxillary palpus with 4 palpomeres, predominantly covered by golden scales, upper portion with violet and blue metallic sheen, palpomere I globose with violet-blue sheen, palpomeres II and IV subequal in length and smaller than III, all with violet-blue sheen, palpomeres with setae, more abundant on palpomere III. Thorax: Length 2.4 mm; integument of scutum dark brown bordered by metallic blue scales and wide central line formed by mixture of metallic golden, blue and green scales. Antepronotum covered by metallic blue scales and 7 or 8 strong setae; postpronotum covered by metallic white scales ( Fig. 1a ); postspiracular areas with 2 strong setae and 3 or 4 smaller ones; proepisternum with metallic white scales and 5 setae; mesokatepisternum and mesanepimeron covered with metallic white scales; mesomeron bare, darkened; scutellum with metallic blue scales and 26 golden marginal setae; mesopostnotum brown, bare ( Fig. 1b ). Legs: Forefemur length 3.1 mm, 0.65 length of proboscis; hindcoxa with metallic white scales and golden setae; all legs with dorsal surface metallic blue-scaled and ventral surface with golden metallic scales, tarsi dark-scaled (also in male); apical portion of tibia with slightly erect scales. Wing: Length 4.4 mm; with scattered golden scales and purple sheen. Halter : Integument yellowish with golden scales. Abdomen ( Fig. 2 ): Length 4.2 mm; terga covered by purple and blue metallic scales with thin coppery apical band increasing slightly in thickness until terminal tergum, basolateral spots of golden scales, last 3 terga with lateral tufts, golden on VI, dark on VII and VIII ( Fig. 2a ); sterna largely covered with metallic golden scales, III–VII with median patch of metallic blue scales (incomplete posteriorly on III), sternum VIII with 2 submedian line of metallic blue scales ( Fig. 2b ).

Male genitalia ( Fig. 3a ). Tergum IX with 2 lobes, each bearing 6 apical setae. Gonocoxite 0,56 mm, covered by scales and setae, with 2 rows of stronger dorsal and internal setae extending from mid-area to apex, basomesal lobe covered with setae, bearing 4 differentiated setae with curved apices decreasing in size, 2 apical ones more evident; gonostylus 0.63 mm, with vestigial setae from mid-area to apex; gonostylar claw 0.15 mm, slightly curved, acute, 0.25 gonostylus length. Paraproct with short denticles and 3 small setae. Aedeagus simple.

Fourth-instar larva ( Figs 4 , 5 ). Chaetotaxy in Table 2 . Head: Length 1.70 mm; dorsal apotome with a median dark brown area surrounding a central circular pale spot, with 2 divergent dark brown lines directed towards palatal brushes and antennae; extended posteriorly into 2 arches directed laterally, lateralia lightly tanned, dark brown around eyes anteriorly ( Fig. 4 ). Antenna: Short, slender. Thorax: Dorsal surface as follows: prothorax with iridescent central spot surrounded by reddish brown area; mesothorax with median dark spot surrounded by several irregularly distributed iridescent yellow and green spots; metathorax dark with 2 iridescent bracket-shaped pink lines with blueish spots laterally. Abdomen: With reddish brown pigmentation and iridescent spots distributed as follows: 2 irregular submedian iridescent lines that pass through all segments, sometimes incomplete from segments IV to VIII, segment III with this iridescent coloring covering almost the entire segment ( Fig. 4 ); seta 1-VII double, setae 2–4,7,9–13-VII single; seta 3-VIII single; seta 1-X spinulate, 4-X fanlike with dendritic branches; saddle incomplete, large, length 0.83 mm, with conspicuous groups of marginal spicules on posterior margin ( Fig. 5 ). Siphon: Length 1.40 mm, width at base 0.41 mm, index 2.9–3.4 (mean 3.2, n = 3); seta 1-S fanlike with aciculate branches.

Pupa ( Figs 3 , 6 ). Chaetotaxy in Table 3 . Abdomen with iridescent sheen spread throughout body, prominent on segment III ( Fig. 6 ). Integument slightly spiculate and tan colored. Cephalothorax ( Fig. 3b ): Trumpet length 0.74 mm; setae 2–4,7-CT single. Abdomen ( Fig. 3c ): Length 5.00 mm; seta 5-III–V long; seta 6-II–V short, 6-VI long; seta 1-IX short, centrally placed. Paddle: Length 1.92 mm, width 1.32 mm; somewhat pentagonal in outline, narrowed basally, enlarging from base to middle portion, tapering towards apex ( Fig. 3c ).

Molecular characterization. The new species was not similar to any species listed in GenBank. Fragments of old specimens identified as Tx. violaceus deposited in the IOC-RJ collection did not have amplifiable DNA. ITS2 sequences are rare in GenBank, so the new ITS2 sequence of Tx. caatingensis was deposited therein ( MF537256 ), but no phylogenetic analysis could be carried out. The CO1 phylogenetic tree ( Fig. 7 ) resolved two clades corresponding to the subgenera Lynchiella and Toxorhynchites . Toxorhynchites caatingensis ( MF537258 ) was included in the clade with other species of the subgenus Lynchiella in the Americas, in closest relationship with Tx. haemorrhoidalis from French Guiana, but with 13% divergence.

Systematics. Toxorhynchites caatingensis is named after the Caatinga, the exclusive biome of northeastern Brazil where it was found. It is a species of the subgenus Lynchiella and is morphologically similar to Tx. violaceus and Tx. mariae . The crucial elements for the differentiation of this species were found to be the size of the female, the presence of blackish caudal tufts on the eighth abdominal segment, blue coloring of the ventral midline of the abdomen, characteristics of the male genitalia, an iridescent sheen in the immature forms, the chaetotaxy of the pupa and its presence in a distinct environment in which the species with the greatest morphological similarity also occur ( Table 1 ).

Habitat. Larvae were collected in the epiphytic bromeliad Aechmea aquilega in a part of the ESEC known as Pororoca, which is an area of approximately 29 ha (0.29 km 2) of denser and more humid forest, compared to its surroundings. It also features undergrowth and trees of up to 15 m in height, with epiphytic plants and lianas ( Marteis et al. 2017a, b).

Type specimens. Holotype: Male (pinned) with associated slide-mounted genitalia and larval and pupal exuviae (specimen field no. L 1862 , accession no. E-15937), BRAZIL: Bahia, Jeremoabo, Estação Ecológica Raso da Catarina (ESEC-RC) ( Raso da Catarina Ecological Station ) (9° 48′ 39.1″ S, 38° 29′ 30.8″ W), 26 September 2014 . Paratypes: Pinned female with associated slide-mounted larval and pupal exuviae (specimen field no. L 2112, accession no. E-15938), 28 September 2014; 2 pinned males with associated slide-mounted genitalia and larval and pupal exuviae (specimen field nos L 1874 and L 1865, accession nos E-15939 and E-15940), 27 July 2014; and one slide-mounted larva (specimen field L 1685, accession no. E-15941), 29 January 2014. The type series is deposited in the entomological collection of the Faculty of Public Health of the University of São Paulo ( USP).

Figures

FIGURE 1. Adult female of Toxorhynchites caatingensis n. sp. (a) Lateral view, right side; (b) dorsal view of thorax and abdomen.

FIGURE 2. Abdomen of the adult female of Toxorhynchites caatingensis n. sp. (a) Dorsal; (b) ventral.

FIGURE 3. Male genitalia (a) and pupa (b, cephalothorax; c, metanotum and abdomen) of Toxorhynchites caatingensis n. sp. (drawn by David Campos Andrade).

FIGURE 4. Larva of Toxorhynchites caatingensis n. sp. (dorsal view).

FIGURE 5. Terminal abdominal segments of the larva of Toxorhynchites caatingensis n. sp. (drawn by David Campos Andrade).

FIGURE 6. Pupa of Toxorhynchites caatingensis n. sp. (lateral view, left side).

FIGURE 7. Phylogenetic tree of CO1 sequences of Toxorhynchites caatingensis n. sp. and 11 other species of the genus, and two outgroup species, deposited in GenBank.