Aphis (Toxoptera) sennae Cheng & Huang, 2023

Cheng, Zhentao & Huang, Xiaolei, 2023, Two new species of Aphis (Toxoptera) Koch (Hemiptera, Aphididae) from China, ZooKeys 1172, pp. 31-46 : 31

Aphis (Toxoptera) sennae Cheng & Huang sp. nov.

Figs 2 , 4D

Description.

Apterous viviparous females: Body pear-shaped, reddish brown in life, with black-and-white banded antennae and dark head, femurs, siphunculi and cauda (Fig. 4D ).

Mounted specimens: Head. Dorsum of head smooth. Antennal tubercles slightly developed. Median frontal tubercle developed, slightly below antennal tubercles. Dorsal hairs 6-7, fine, with small developed tuberculate bases. Head with one pair of cephalic hairs, one pair of antennal tubercular hairs. Antennae six-segmented, segments I and II smooth, dark brown, segments III-VIb and PT imbricated, dark at distal end. Whole antennae 0.8-0.9 times as long as body. Length in proportion of segments I-VI: 19-25, 19-22, 100, 59-69, 61-69, 25-31 + 94-116. Processus terminalis 3.4-4.1 times as long as basal part of the segment. Antennal segments I-VI each with 4, 4, 5-9, 3-5, 3-4, 2-3 + 4-6 hairs, respectively, apex of processus terminalis usually with 3-4 hairs. Length of hairs on segment III 0.01 mm, 0.3 times as long as the widest diameter of segment III. Rostrum reaching hind coxae. Ultimate rostral segment wedge-shaped, 2.0-3.3 times as long as basal width, 1.2-1.4 times as long as second hind tarsal segment. Ultimate rostral segment with three pairs of hairs, including one pair of accessory hairs.

Thorax. Mesosternal furca with separated arms. Length of single arms 0.10-0.14 mm, 0.3-0.4 times as long as antennal segment III. Prothorax with one pair of small marginal tubercles. Dorsal hairs on thorax short and thin, with small tuberculate bases. Legs normal. Distal part of femora, basal and distal part of tibiae dark brown, others brown. Hind femur 1.4-1.5 times as long as antennal segment III. Hind tibia 0.5-0.6 times as long as body, with 8-10 peg-shaped spines, on basal two-thirds of inner side. Length of hairs on hind tibia 0.02-0.03 mm, 0.8-1.0 times as long as the widest diameter of antennal segment III. First tarsal chaetotaxy: 3, 3, 2. Second tarsal segments with transverse imbrications.

Abdomen. Abdominal segments IV-VI with ventro-lateral spinulose ridges, forming a stridulatory surface. Abdominal segments I and VII each with one pair of marginal tubercles. Abdominal dorsal hair sparse, fine, with tuberculate bases. Abdominal tergite VIII with two hairs. Siphunculi dark brown, cylindrical, tapering towards the apex, with spinulose transverse imbrications, without flange or hairs. Siphunculi 0.17-0.20 mm, 1.9-2.7 times as long as its basal diameter, 0.9-1.1 times as long as cauda. Cauda short tongue-shaped, constricted in middle, 1.2-1.8 times as long as its basal diameter, with 9-17 hairs. Anal plate broad, with 20-29 hairs. Genital plate transversely oval, with 8-13 hairs. Cauda, anal plate and genital plate dark brown with dense spinules. Gonapophyses three, each with 4-5 hairs.

Specimens examined.

Holotype: apterous viviparous female, China: Yunnan (Kunming, 25.1°N, 102.7°E, Alt. 1900 m), 11 Nov. 2017, No. HL _zld20171111_7_A, on Senna bicapsularis coll. L. D. Zeng (FAFU) . Paratypes: 7 apterous viviparous females (No. HL_zld20171111_7_B, No. HL_zld20171111_7_C, No. HL_zld20171111_7_D, No. HL_zld20171111_7_E, No. HL_zld20171111_7_F, No. HL_zld20171111_7_G and No. HL_zld20171111_7_H), with the same collection date as holotype (FAFU).

Etymology.

The new species is named after the genus name of the host plant, Senna bicapsularis . The word ‘sennae’ is a noun, and does not change spelling based on gender.

Host plant.

Senna bicapsularis (L.) Roxb. ( Fabaceae ).

Distribution.

China: Yunnan Province (Kunming).

Biology.

It seems the species feeds on seed pods of the host plant.

Taxonomic notes.

Aphis (T.) sennae Cheng & Huang, sp. nov. has black-and-white banded antennae, and processus terminalis are dark, different from A. aurantii whose processus terminalis are dark basally and distally. Siphunculi length 1.9-2.7 times of siphunculi basal width ( A. aurantii : 2.0-3.8 times). The body length of A. (T.) sennae Cheng & Huang, sp. nov. is 1.50-1.89 mm, which is significantly larger than A. (T.) fafuensis Cheng & Huang, sp. nov. (0.91-1.19 mm). Body color of A. (T.) sennae Cheng & Huang, sp. nov. is reddish brown, the head is slightly darker, and immatures are almost the same color as adult apterae. Adult apterae of A. aurantii and A. (T.) fafuensis Cheng & Huang, sp. nov. are brownish-black, the nymphs of these two species are lighter in body color, or reddish brown. The results of ANOVA analysis and the LSD test revealed significant differences between A. (T.) sennae Cheng & Huang, sp. nov. and A. (T.) fafuensis Cheng & Huang, sp. nov., as well as between A. (T.) sennae Cheng & Huang, sp. nov. and A. (T.) aurantii , in a number of characters, including the measured length, ratio, and number of hairs on various body parts (Suppl. material 1: table S2).

Molecular analyses

The mean interspecific distance between A. (T.) fafuensis and A. (T.) aurantii was 2.8%, and the K2P distances between A. (T.) fafuensis and other species from Aphis (Toxoptera) ranged from 5.6% to 9.2%. Meanwhile, the mean interspecific distance between A. (T.) sennae and A. (T.) aurantii was 2.7%, and the K2P distances between A. (T.) sennae and other species within Aphis (Toxoptera) ranged from 4.5% to 8.2%. The averages of pairwise sequence divergences of the COI genes among thirty-six samples are presented in Table 3 .

The phylogenetic results showed that A. (T.) fafuensis Cheng & Huang, sp. nov. and A. (T.) sennae Cheng & Huang, sp. nov. clustered together with the known species of Aphis (Toxoptera) . Both the two new species showed morphologically and phylogenetically closer relationships with A. (T.) aurantii and A. (T.) fafuensis had a sister relation with A. (T.) aurantii , probably due to closer relationship of their host plants.

Figures

Figure 2. Aphis (Toxoptera) sennae Cheng & Huang, sp. nov., apterous viviparous female A dorsal view of body B dorsal view of head C antennal segments I-III D antennal segments V-VI E mesosternal furca F ultimate rostral segment G siphunculus H genital plate I cauda J ventro-lateral stridulatory ridge of abdominal segments IV-VI K stridulatory ridge L anal plate M peg-shaped hairs on hind tibia N marginal tubercle on prothorax O marginal tubercle on abdominal segment I P marginal tubercle on abdominal segment VII Q gonapophyses. Scale bars: 0.10 mm. (D, J, Q from HL _ zld 20171111 _ 7 _ A; B, H, M from HL _ zld 20171111 _ 7 _ B; L from HL _ zld 20171111 _ 7 _ C; A, E, G, I, K, N, O, P from HL _ zld 20171111 _ 7 _ D; B from HL _ zld 20171111 _ 7 _ G; F from HL _ zld 20171111 _ 7 _ H.).

Figure 4. A-C Aphis (Toxoptera) fafuensis Cheng & Huang, sp. nov., colony on the shoot and the underside of leaf of Adinandra millettii D Aphis (Toxoptera) sennae Cheng & Huang, sp. nov., colony on the seed pod of Senna bicapsularis.