Thelacantha brevispina (Doleschall, 1857)

Macharoenboon, Kongkit, Siriwut, Warut & Jeratthitikul, Ekgachai, 2021, A review of the taxonomy of spiny-backed orb-weaving spiders of the subfamily Gasteracanthinae (Araneae, Araneidae) in Thailand, ZooKeys 1032, pp. 17-62 : 17

Thelacantha brevispina (Doleschall, 1857) Figures 10 , 12J-L

Plectana brevispina Doleschall, 1857: 423. Type locality: Indonesia, Ambon Island.

Plectana brevispina Full list of synonyms and usage of the name available in World Spider Catalog (2020).

Material.

Thailand • 4 ♀; Samut Sakhon Province, Khok Kham District ; 13°29.27'N, 100°20.13'E; MUMNH-ARA-THE003 • 3 ♀; Phetchaburi Province, Ban Laem District ; 13°02.55'N, 100°05.55'E; MUMNH-ARA-THE004 • 5 ♀, 2 ♀ juvenile; Surat Thani Province, Ko Pha-ngan District , Koh Tao Is.; 10°04.07'N, 99°49.16'E; MUMNH-ARA-THE005 • 5 ♀; Loei Province, Phu Ruea District , Lat Khang; 17°31.55'N, 101°15.33'E; MUMNH-ARA-THE007 • 5 ♀; Samut Songkhram Province, Mueang District , Bang Kaeo; 13°23.18'N, 100°02.18'E; MUMNH-ARA-THE008 • 2 ♀; Trat Province, Laem Ngop District , 12°10.38'N, 102°24.33'E; MUMNH-ARA-THE009 .

Diagnosis.

Sternum black. Sternal band various in shape. Abdomen octagonal, slightly wider than long. Color pattern on dorsal abdomen various but frequently with two large white spots. Three pairs of abdominal spines similar in shape, tubercle with small protuberance at the tip. Ventral side of abdomen black, with scattered yellowish stripes. Ten anterior edge sigilla subequal in size. Four median sigilla arranged in a trapezoid. Ten posterior edge sigilla, the middle pair very small, and close together. Outer posterior edge with five sigilla, located near posterior spines. Epigynum relatively simple in shape with bracket-shaped scape (Fig. 12K ). Spermathecae oval, placed close together (Fig. 12J, K ). Fertilization duct short, emerging posteriorly from spermathecae (Fig. 12J ).

Variation.

Thelacantha brevispina shows high color variation on abdomen. Four color morphs were found in this study: (1) the multi-colored morph (Fig. 10A, B ) is decorated with white, black, and red patches on the dorsal abdomen; (2) the black-white morph (Fig. 10C ) possesses a vertical central black line from the anterior to the base of the posterior spines with white areas on each side; (3) the black morph (Fig. 10D ) shows a completely black abdomen without the two large white spots; (4) the orange morph (Fig. 10E ) is characterized by a bright orange abdomen with two white spots. Such morphotypes are found in adult spiders, except in the orange morph, which was a juvenile specimen. The multi-colored morph was found in every population, whereas the other morphs were relatively rare.

Remarks.

Thelacantha brevispina has been noted for the two large, distinct white spots on its abdomen ( Pickard-Cambridge 1879; Chrysanthus 1959; Emerit 1974; Tikader 1982; Barrion and Litsinger 1995; Yin et al. 1997; Dierkens and Charlat 2011). Some color morphs in this study have been reported in previous works such as the Multi-color morph ( Dierkens and Charlet 2011) and the Black-White morph ( Tikader 1982). Thelacantha brevispina is widely distributed on a global scale. It has been recorded from Madagascar to Australia and also oceanic islands such as French Polynesia, and Fiji ( Emerit 1974; Barrion and Litsinger 1995; Dierkens and Charlat 2011). Currently, it is classified as a monotypic species ( World Spider Catalog 2020). However, the results of species delimitation have demonstrated four distinct species in the T. brevispina lineage (Fig. 4 , T1-T4). Worldwide taxon sampling may reveal a large number of cryptic species, and elucidate their taxonomic status.

Distribution and habitat.

India, Pakistan, Bangladesh, Sri Lanka China, Taiwan, Japan, Korea, Myanmar, Thailand, Malaysia, Indonesia (Ambon, Java, Sumatra, and Sulawesi), Philippines, New Guinea, Australia, Fiji, Mauritius, French Polynesia, Hawaii, and Madagascar ( Emerit 1974; Tikader 1982; Yin et al. 1997, 2012; World Spider Catalog 2020). In this study, Thelacantha brevispina was found widely dispersed in coastal areas. They were commonly found in mangrove forests along the Inner Gulf of Thailand, but one population was found in the mountainous area in Phu Ruea District, Loei Province, which is far from the sea. These spiders build a vertical web between trees in open areas and sit at the center of the web.

Figures

Figure 4. Ultrametric tree generated by BEAST from 675 bp of COI gene showing clusters of OTUs as suggested by morphological identification, and three molecular species delimitation algorithms, ABGD, bPTP, and GMYC. Nodal support values are labeled as MP Jackknife support / ML bootstrap values / Bayesian posterior probability. Gene tree from MP and ML analyses are available as Suppl. material 1 (Suppl. material 1: Figs S 3, S 4).

Figure 10. Females of Thelacantha brevispina showing dorsal view (left) and ventral view (right) A, B multi-color morph A specimen from Phetchaburi (MUMNH-ARA-THE 004) B specimen from Samut Songkhram (MUMNH-ARA-THE 008) C black-white morph, specimen from Loei (MUMNH-ARA-THE 007) D black morph, specimen from Samut Songkhram (MUMNH-ARA-THE 008) E orange morph, specimen from Surat Thani (MUMNH-ARA-THE 005).

Figure 12. Female genitalia of A-C Macracantha arcuata D-I M. hasselti J-L Thelacantha brevispina. Genitalia are shown in dorsal view (A, D, G, J), ventral view from external (B, E, H, K), and posterior view (C, F, I, L).