Anoplodactylus eroticus Stock, 1968

Wang, Jianjia, Lin, Heshan, Huang, Dingyong, Zheng, Xinqing, Liu, Qinghe, Wang, Jianjun, Niu, Wentao & Zhang, Feng, 2020, Recent collections of sea spiders (Arthropoda: Pycnogonida) from China seas, with some new records and a checklist of the area, Zootaxa 4802 (2), pp. 361-373 : 366-369

Anoplodactylus eroticus Stock, 1968

( Fig. 3 a-f)

Anoplodactylus eroticus Stock, 1968: 49 , fig. 18; Arango and Maxmen, 2006: 55, figs. 2a–2e, 3a, 3b, 4, 5; Lucena et al. 2015: 435 , figs. 12–28; Lucena and Christoffersen, 2018a: 111 ; Lucena and Christoffersen, 2018b: 375 (key), 376–377.

Syn.: Anoplodactylus sp.— Maxmen et al., 2005.

Material examined Male with eggs (P18–B0911SL6–01), Putian, Fujian, China, 25.27°N 119.37°E, 5 m depth, 28 Nov. 2017 .

Measurements (mm) Trunk length (from chelifore insertion to tip of 4th lateral processes), 2.35; trunk width (across 2nd lateral processes), 1.55; proboscis length, 1.21; length of scape of cheliphore, 0.91; length of chela, 0.48; abdomen length, 0.38.

Third leg, coxa 1, 0.49; coxa 2, 0.87; coxa 3, 0.58; femur, 1.92; tibia 1, 1.69; tibia 2, 1.69; tarsus, 0.15; propodus, 0.84; claw, 0.54; auxiliary claw, 0.07.

Distribution The species of Anoplodactylus eroticus widely and discretely distributed. The holotype was collected from the Gulf of Manaar in India, and the paratype was found in Honolulu Harbor, Hawaii ( Arango & Maxmen 2006). Arango & Maxmen (2006) collected females of A. eroticus for the first time in Kewalo Basin of Honolulu in Hawaii. Lucena et al. (2015) and Lucena & Christoffersen (2018b) reported the new record of this species from Alagoas, Paraíba, Rio Grande do Norte, Ceará, Piauí, and Maranhão in Brazil. Though the sampling locations were scattered across the Indian, Atlantic and Pacific Oceans, this new Chinese record, also new to the West Pacific, made the distribution more continuous.

Depth There was no explicit range of sampling depth except specimens gathered from 1–5 m below sea level in Kewalo Basin, Honolulu, Hawaii ( Arango & Maxmen 2006; Lucena & Christoffersen 2018b). The depth of this new record which was consistent with above range, suggested A. eroticus might be a shallow water species.

Remarks This ovigerous male specimens was identified as A. eroticus based on the second coxae of all legs with ventrally long spurs, the lateral processes with short spines, a small but distally erect cement gland duct, and the femurs without spurs ( Stock 1968; Arango & Maxmen 2006; Lucena & Christoffersen 2018b).

The description of female ( Arango & Maxmen 2006) and specimens obtained from Brzail ( Lucena et al. 2015) complemented the original description, and also illustrated the differences between specimens gathered from Atlantic and Indo–Pacific. Lucena et al. (2015) regarded these differences, more numerous setae on apendages and ten sole spines of the propodus of male, lateral pocesses with three short setae of female, as morphological variations. The number of sole spines varied from seven to twelve in the specimen examined in this study ( Fig. 3 e-f). Despite obvious damage on some legs, especially on the propodus, at least twelve sole spines were different from any previous records and the presumed actual number of sole spines might be twelve according to the apparently complete propodus with twelve sole spines. It was reasonable to identify this specimen as A. eroticus with no significant morphological differences with previous ones.

Lucena et al. (2015) summarized the gynandromorphism in Anoplodactylus based on literatures and their new finding on the Atlantic material of A. eroticus . According to their description, the present specimen should be genuine male.

Arango & Maxmen (2006) collected specimens of the species on the hydroid, Pennaria disticha Goldfuss, 1820 , attached to suspended objects, but such an association was not found in the Atlantic specimens ( Lucena et al. 2015). Our specimen was also found to be associated with P. disticha which was distributed in East and South China Seas ( Liu 2008). Given the present records, A. eroticus was likely to be a tropically and/or warm–temperately distributed species, like P. disticha . Furthermore, Dietz et al. (2018) described Anoplodactylus as a generalist feeder and overviewed the studies about the species of this genus feeding on the hydroids. Accordingly, it was necessary to test the actual relationship between A. eroticus and P. disticha . The ovigerous specimen in this study, which implied more individuals inhabiting locally, might support an opportunity to test relationships with other organisms, especially the suspected P. disticha , and also to explore spread models of slow–moving species without planktonic larval stages.

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*New to China; **Endemic to China

Figures

FIGURE 3. Anoplodactylus eroticus Stock, 1968 (P18–B0911SL6–01) male, a. trunk, dorsal view; b. trunk, lateral view; c. trunk, ventral view; d. ventrally spurs on the second coxae of leg 2 and 3; e. tarsus, propodus and claw of leg 2, arrows indicating the sole spines; f. tarsus, propodus and claw of leg 3, arrows indicating the sole spines. Scale bars a, b=1 mm, c, d =0.5 mm, e, f=0.2 mm.