Afronurus rubromaculata You, Wu, Gui & Hsu, 1981

Wongyam, Anuntaya, Sartori, Michel & Boonsoong, Boonsatien, 2023, Unravelling the diversity of the genus Afronurus Lestage, 1924 (Ephemeroptera, Heptageniidae) in Thailand, ZooKeys 1176, pp. 55-78 : 55

Afronurus rubromaculata You, Wu, Gui & Hsu, 1981

Figs 13A-E , 14A-E , 15A-C , 16A-E , 17E, F

Cinygmina rubromaculata You, Wu, Gui & Hsu, 1981: 4, figs 14-24 (original description, male and female).

Cinygmina rubromaculata - Wu, Chen, Cong & You, 1986: 1, 67.

Cinygmina rubromaculata - Zhou and Zheng 2003: 758, figs 7, 8, 13,17 (nymph first description).

Afronurus rubromaculatus - Braasch and Jacobus 2011: 65.

Afronurus rubromaculata - Boonsoong and Braasch 2013: 88.

Afronurus rubromaculatus - Zhang et al. 2021: 110.

Material examined.

11 nymphs, Chanthaburi Prov. , Klong Phlu Lang , 12°43.207'N, 102°23.321'E, 115 m, 5.VI.2018, W. Anuntaya leg. (ZMKU); 2 nymphs, Kanchanaburi Prov. , Tao Taan, 14°38'58.199"N, 98°34'55.8006"E, 116 m, 31.I.2019, W. Anuntaya leg. (ZMKU); 3 nymphs, Nan Prov., Na noi, 18°19'22.0002"N, 100°43'14.0016"E, 289 m, 5.XII.2017, B. Boonsoong leg. (ZMKU); 15 nymphs, Ratchaburi Prov., Kang Som Maew, 13°24'22.32"N, 99°6'43.74"E, 207 m, 24.XI.2018, W. Anuntaya leg. (ZMKU) .

Description.

Nymph. See Zhou and Zheng (2003: 757, figs 7, 8, nymph first description).

Adult. Male imago. See You et al. (1981: 28, figs 14-24, original description).

Eggs.

Chorionic surface of egg with dense pKCTs on each pole and eKCTs (Fig. 16A ). Equatorial and subequatorial areas with eKCTs and micropyle next to eKCTs (Fig. 16C ); the area between pKCTs and eKCTs smooth (Fig. 16B ), areas of two poles of pKTCs ~ 0.47 × that of the whole egg (Fig. 16A ).

Diagnosis.

Nymph of A. rubromaculata is easily distinguishable from other Afronurus species by the following characteristics: anterior margin of head with four distinct pale yellow markings and a row of four pale dots in front of antenna bases and three pairs of pale markings between eyes (Fig. 13C ), thorax with pattern as shown in Fig. 13A . Abdominal tergites II-VII with pair of pale marks on sub-median and posterolateral areas, sub-median marking of tergite V fused, large; tergites VIII and IX each with sub-median pale marking; tergite X with anterior pale area (Fig. 13B ). Sternites IX and X brown (Fig. 13D ). Gills V (Fig. 14A ) and VI (Fig. 14B ) obliquely rounded, triangular, with projection; asymmetrical gill VII (Fig. 14C ). Markings of hind femur as shown in Figs 13E , 14D . Bristles on the dorsal face of the hind femur pointed (Fig. 14E ).

Adult male is distinguishable by genitalia and abdominal pigmentation; genital plate emarginated, divided into two lobes, inner lobe broad. The cleft between lobes U-shaped with a small tubercle (Figs 15C , 17E, F ), outer lobe canine-like. The titillators robust, canine-like. Forceps comprising four segments, segment I very short, length ratio of segment II to segment III to segment IV is 0.45: 0.14: 0.13 (Fig. 8C ). Adult female with anal plate triangular, slightly truncate at tip (Fig. 15D ).

Distribution.

Chanthaburi, Kanchanaburi, Nan, and Ratchaburi provinces (Fig. 18 ).

Remarks.

Afronurus rubromaculata is a common species in Thai streams and widely distributed (Fig. 18 ). Suitable localities for A. rubromaculata appear to be with cobbles deep in running water, the area mostly covered with riparian fields. Afronurus rubromaculata has a unique pattern on the abdomen. She et al. (1995) described the differentiation of the spine position between A. rubromaculata and A. hainanensis , but Zhou (2013) synonymised A. rubromaculata and A. hainanensis due to the similarity of the spine on the penes that varies in size. However, in Thailand, the penial character of A. rubromaculata is distinct from that of other species of Afronurus in Thailand (Table 3 ). In this study, the egg morphology of A. rubromaculata was similar to that of a Chinese specimen, with a smooth surface in the equatorial area ( Zhang et al. 2021: fig. 6E).

Molecular analysis

The Bayesian inference tree is shown in Fig. 19 . The 37 samples of Thai Afronurus are grouped into four major clades: Afronurus rainulfiana , A. cervina , A. gilliesiana , and A. rubromaculata . Each clade is monophyletic, and strongly supported by the Bayesian posterior probabilities. The intraspecific and interspecific genetic distances are given in Table 2 . The range of genetic distances within species is 3%-4%, whereas the range of genetic distances between species is 7%-30%. Afronurus rainulfiana is clearly supported as a monophyletic clade with the sequence of Afronurus sp.1 (Surat Thani Prov.) from Yanai et al. (2017). The A. cervina clade was divided into two sub-clades due to geography; however, the intraspecific genetic distance is 3%. The species A. mnong (Vietnam) was clustered with the A. cervina clade, with a low genetic distance (7%). By contrast, A. meo (Vietnam) was grouped with the A. gilliesiana clade and showed a relatively high genetic distance (18%). Afronurus hyalinus (Taiwan) was clustered with the Thai clade of A. rubromaculata . Surprisingly, the A. rubromaculata sequence from China is in a different clade than the Thai A. rubromaculata sequence (genetic distance 22%), while A. namnaoensis was clustered in the A. rubromaculata clade with low genetic distance (4%).

Figures

Figure 8. Afronurus gilliesiana (Braasch, 1990), SEMs of egg morphology A general outline of egg B chorion surface between polar KCT (pKCT) and equatorial KCT (eKCT) C micropyle (M) and enlargement of eKCTs. Scale bars: 50 μm (A); 20 μm (B); 10 μm (C).

Figure 13. Afronurus rubromaculata (You et al., 1981), larval morphology A female habitus B tergite I-X D sternite VI-X C head E hind leg. Scale bars: 1 mm.

Figure 14. Afronurus rubromaculata (You et al., 1981), larval morphology A gill V B gill VI C gill VII D bristles on the dorsal face of the hind femur E enlargement of bristles on basal part. Scale bars: 1 mm (A-D); 0.25 mm (E).

Figure 15. Afronurus rubromaculata (You et al., 1981), imaginal morphology A male tergites III-X B female tergites II-X C male genitalia D female anal plate E fore wing and hind wing. Scale bars: 0.5 mm (C, D); 1 mm (A, B, E).

Figure 16. Afronurus rubromaculata (You et al. 1981), SEMs of egg morphology A general outline of egg B chorion surface between polar KCT (pKCT) and equatorial KCT (eKCT) C micropyle (M) and enlargement of eKCTs. Scale bars: 50 μm (A); 20 μm (B); 10 μm (C).

Figure 17. male genitalia A, B A. cervina C, D A. gilliesiana E, F A. rubromaculata (arrow indicates titillators).

Figure 18. Distribution map of the genus Afronurus in Thailand.

Figure 19. Bayesian inference tree of the DNA barcoding (COI) profile for 37 sequences of the genus Afronurus with branch probability support.