Chaitoregma kirlia Wang & Huang, 2024, sp. nov.

Chaitoregma kirlia sp. nov. Figs 1, 2, 3, Table 1 Etymology. The specific epithet “ kirlia ” is a noun in apposition, named after Kirlia, a character from the popular Pokémon series. They both have a pair of front horns. The name was chosen to honor the graceful and elegant nature of this new species, reminiscent of the character. Description. Apterous viviparous female: body oval, dark purple in life. Body dorsum slightly covered with white wax powders, marginal areas on body with undeveloped flaky wax powders in life. For morphometric data see Table 1. Mounted specimens. Body oval and dark sclerotic (Fig. 1 A), 1.62–1.82 × as long as its width, sclerotic areas evenly covered with numerous irregularly shaped wax facets, wax facets arranged radially at the intersegmental area (Fig. 1 J). Head and pronotum fused (Fig. 1 B), mesonotum, metanotum, abdominal segment I and VIII mutually free; abdominal segment II to VII completely fused, sutures not clearly distinct. Head. Frons with a pair of frontal horns, frontal horns cylindrical with broadly rounded tips, about 1.2–1.7 × as long as their basal width, smooth, with 6–12 short setae (Fig. 1 C). Distance between the apex of the horns about 0.109 –0.125 mm. Embryo with blunt frontal horns (Fig. 1 F). Antennae 4 - segmented, sometimes 5 - segmented, about 0.15–0.19 × body length (Fig. 1 H); length in proportion of segments I – IV: 25–37, 25–30, 64–73, 40–52, and 18–27. Antennal setae all fine, long with acute apices; segments I – V with 1–2, 2–3, 3–6, 1–2 setae, respectively; apical part of processus terminalis with 2–5 setae (Fig. 1 F). Length of setae on segment III 0.02–0.045 mm. Segment III narrowed toward base, sensorium very small. Eyes with 3 facets in apterae. Rostrum short, reaching or nearly reaching mid-coxae; URS wedge-shaped (Fig. 1 E), about 0.60–0.75 × of second joint of hind tarsi, with 3 pairs of long primary setae. Dorsal head and pronotum with 15–20 setae, 0.050 –0.066 mm, fine wavy, with acute apices. Thorax. Margin of the pronotum to metanotum each with some wax facets (Fig. 1 D). Dorsal setae on thorax similar to head setae. Pronotum with 2 pairs of spinal setae and 2 pairs of marginal setae; mesonotum, and metanotum each with 2 pairs of spinal, 1–2 pair of pleural and 2 pairs of marginal setae, respectively. Mesosternal furca with 2 separated arms (Fig. 1 G), each arm 1.53–2.47 × as long as basal diameter of antenna segment III. Legs short, trochanters nearly fused with femora; hind tibia 0.22–0.26 × as long as body. Setae on legs fine and slightly long; setae on hind tibia 0.90–1.27 × as long as its diameter. First tarsal chaetotaxy: 4, 3, 2. The first fore tarsal joint of the legs with 2 long setae and 2 short setae (Fig. 1 K), while the first hind tarsal joint with 2 long setae. Abdomen. Abdominal tergites I – VII each with 1 pair of wax gland plates on marginal sclerites, composed with irregularly shaped to rounded wax gland facets (Fig. 1 L), surrounding 1 marginal seta, wax gland facets composed with 2–5 facets. Abdominal tergites I – V each with 2 pair of spinal setae, 2–4 pair of pleural and 1 pair of marginal setae; tergites VI with 1 pair of spinal, 1 pair of pleural and 1 pair of marginal setae; tergites VI with 1 pair of spinal and 1 pair of marginal setae; tergite VIII with 8–16 setae (Fig. 2 C), setae on abdominal tergite VIII 2.9–3.7 × as long as basal diameter of antennal segment III. Spiracles round, open. Siphunculae pore-like, about 0.03 mm, slightly elevated, not situated on setaceous cones (Fig. 2 A). Cauda knobbed and constricted at base, with about 3–7 setae (Fig. 2 E). Anal plate bilobed, with 5–7 setae on each lobe (Fig. 2 E). Genital plate with 4 anterior setae and 7–9 posterior setae (Fig. 2 B). Gonapophyses two, each with 5–7 setae (Fig. 2 D). Specimens examined. Holotype • 1 apterous viviparous female, China: Fujian (Mount Wuyishan, 27.630 ° N, 117.394 ° E, alt. 234 m), 12 Aug. 2016, HL_20160812_19_A, coll. X. L. Huang and X. L. Lin (FAFU). Paratypes • 7 apterous viviparous females (HL_20160812_19_B to D on the same slide as holotype; HL_20160812_19_E to G on another slide), with the same collection data as holotype. Other examined material. • 3 apterous viviparous females on the same slide, China: Guangdong (Mount Lianhuashan, 23.067 ° N, 115.241 ° E, Alt. 905 m), 16 July 2024, WYZ_20240716_6_A to D, coll. Y. Z. Wang (FAFU). Distribution. China: Fujian (Mount Wuyishan), Guangdong (Mount Lianhuashan). Host plants. One unknown species of Bambusoideae. Biology. According to our records, Chaitoregma kirlia forms large colonies on the undersides of leaves of the host plant, and can be attended by ants, Crematogaster sp. (Fig. 3). In the wild, it has been observed that in addition to the purple individuals of this new species within the colony, there are occasionally a few yellow individuals; these are suspected to be mixed colonies with another Chaitoregma species, possibly C. tattakana suishana (Fig. 3). The entire life cycle is unknown. Taxonomic notes. The new species resembles the type species C. tattakana (Takahashi, 1925), they but differ as follows: C. kirlia sp. nov. has distinct wax gland plates on the margin of abd. I – VI (Fig. 1 L), while other species in this genus do not have distinct wax gland plates (Qiao and Zhang 2003, Fig. 2 G); The new species has a greater distance between the apex of the frontal horns (0.109 –0.135 mm) compared to C. tattakana tattakana (0.098 –0.110 mm); length of the setae on the dorsum of head (0.050 –0.066 mm), abd. tergites I (0.035 –0.059 mm) and VIII (0.042 –0.072 mm) are significantly shorter than C. tattakana tattakana (0.079 –0.112 mm; 0.056 –0.113 mm; 0.062 –0.096 mm); HT 0.22–0.26 × body length (C. tattakana tattakana: 0.25–0.30 ×), PT 0.4–0.68 × Ant. IV (C. tattakana tattakana: 0.27–0.48 ×), URS 0.78–1.04 × URS _ BW (C. tattakana tattakana: 1.16–1.43 ×), URS 0.60–0.75 × 2 HT (C. tattakana tattakana: 0.54–0.58 ×). Number of setae on various body parts are also different (Table 1). According to the original description, C. kirlia sp. nov. differs from C. aderuensis at least by following: HT 0.26–0.30 mm (C. aderuensis: 0.37 mm); WA 0.18–0.21 mm (C. aderuensis: 0.23 mm). Molecular analyses The phylogenetic results illustrate the evolutionary relationships among some species within the tribe Cerataphidini, highlighting the new species marked in red. The sequences of C. kirlia and C. tattakana tattakana cluster into two distinct clades, indicating clear genetic divergence between them (Fig. 4). Genetic distance threshold has been used as the basis for species classification, and in aphid groups, a generally applicable threshold range is from 2 % to 2.5 % (Liu et al. 2013; Lee et al. 2017; Zhu et al. 2017; Li et al. 2019, 2023). The K 2 P distances between C. kirlia and other species was around 7.19–7.61 % (Table 3). This significant genetic distance, exceeding the typical threshold range, supports C. kirlia as a distinct species.