Artemia cf. sinica Cai, 1989

Dadykin, Ivan A., Karimov, Gafur N., Sinev, Artem Y., Volkova, Polina A. & Kotov, Alexey A., 2024, Branchiopoda (Crustacea: Anostraca and Diplostraca) diversity in Tajik Pamir and plain West and South Tajikistan, Zootaxa 5497 (1), pp. 1-32 : 15

Artemia cf. sinica Cai, 1989

( Fig. 2 , Figs. 4 A, B )

Description. Male. Body length 6.5–9.5 mm. Distal segment of second antenna widened, subtriangular ( Fig. 2A, B ). Apophyses subspherical, with evenly spaced small solitary spines ( Figs. 2B, C ).

Eleven thoracic somites, each bears a pair of limbs. Limbs have a basically similar structure: a single leaf-like pre-epipodite; an epipodite; exopodite and endopodite bearing a single row of feathered setae; endites with two rows of setae ( Figs. 2D, G ). Endites 3–5 subconical; endites 1 and 2 spatulate, endite 1 wider than endite 2. Thoracic limb I with a short, ovoid exopodite and a short, wide endopodite, bearing similar feathered setae progressively elongating towards their distal ends ( Fig. 2D ). Endite 5 with a single seta of outer row and two long thick setae of the inner row; endite 4 with two outer setae subequal in size and two inner setae; endite 3 with two outer setae, one 3–3.5 times longer than the other, and three inner setae of similar size and structure ( Fig. 2D ). Endite 2 bears two outer spines on its dorsal margin, one of them very short ( Fig. 2E ); endite 1 with two small spines and a large thick spinulated seta in the center of the inner margin of endite ( Fig. 2F ).

Thoracic limb V with an inner part of endopodite armed by thick scraper-like setae increasing in length towards the distal end ( Fig. 2G ). General structure and armature of the endites are similar to that of the limb I. Gonopod relatively short ( Fig. 2H ), basal portion bearing an acute spine armed distally with short spinulae ( Fig. 2I ); eversible portion ventrally with a row of spines along the midline ( Fig. 2H ).

Female. Body length 5.5–11 mm. General structure of the thoracic limbs conforms to that of the male. Egg pouch subtriangular, inflated laterally, with a short distal outgrowth. Ventral surface with two symmetrical spines mediolaterally ( Fig. 2J ). Cyst size 0.22–0.255 mm, cyst surface almost smooth ( Figs. 4A, B ).

Remarks. The species was previously reported from the same locality (Lake Chukurkul, Tajik Pamir) as Artemia salina (Linnaeus, 1758) . The morphological differentiation within Artemia is rather difficult ( Mura & Brecciaroli 2004; Sainz-Escudero et al. 2021), thus discriminant analysis or molecular methods usually are applied for identification ( Sainz-Escudero et al. 2021; Zheng & Sun 2023). Several Artemia species are known from Asia, including A. salina (Linnaeus, 1758) , A. sinica Cai, 1989 , A. tibetiana Abatzopoulos et al., 1998 , A. murae Naganawa & Mura, 2017 , and A. urmiana Günther, 1899 ( Litvinenko et al. 2009; Naganawa & Mura 2017). The observed population is clearly distinct from A. salina in having subsphaerical apophyses and spine-like projections on basal part of the gonopod. Also, it differs from A. murae , A. tibetiana and A. urmiana by armature of the apophysis; from A. tibetiana and A. urmiana by form of the gonopod basal process ( Mura & Brecciaroli 2004; Naganawa & Mura 2017); from A. tibetiana by smaller cyst diameter (0.22–0.25 mm versus 0.3– 0.25 mm in A. tibetiana, Abatzopoulos et al. 1998 ). A. sinica was observed in China (Shanxi, Hebei, Inner Mongolia) and Tyva ( Van Stappen, 2002; Litvinenko et al. 2009; Naganawa & Mura 2017). However, the presence of A. salina in Tajikistan cannot still be excluded. In Tajikistan, the populations of Artemia were found in several hyperhaline lakes in Pamir ( Werestschagin 1923; Akhrorov 2001; this study, loc. 34). For more information on morphology of A. sinica , see Mura & Brecciaroli (2004); Zheng & Sun (2008).

Figures

FIGURE 2. Artemia cf. sinica Cai, 1989 from hyperhaline lake Chukurkul, Tajik Pamir (loc. 34). A–I, male. A, head, anterior view. B, antenna, anterior view. C, apophysis, anterior view. D, thoracic limb I, anterior view. E, anterior setae of endite 2; F, anterior setae of endite 1. G, thoracic limb V. H, gonopods, ventral view. I, basal spine of gonopod. J, female, egg pouch, ventral view. Abbreviations: ap, apophysis of second antenna; bp, basal portion of gonopod; c, cyst; e1–5, endites; en, endopodite; ex, exopodite; ep, eversible portion of gonopod; epp, epipodite; pep, pre-epipodite.

FIGURE 4. Cysts of Anostraca from Tajik Pamir (SEM). A, B, Artemia cf. sinica Cai, 1989 from Lake Chukurkul (loc. 34). C–F, Chirocephalus cf. bobrinskii (Alcock, 1898). C, puddle in Alichur River valley (loc. 30). D, puddle in Lake Zorkul Valley (loc. 36). E, F, puddle in South Toguzbulak River valley (loc. 51).