Acroperus africanus Neretina and Kotov, 2015

Lee, Sue Yeon, Yoo, Jung Sun & Kim, Seung Tae, 2017, Recent progress in studies of the Cladocera (Crustacea: Branchiopoda) of South Korea with seven new records for the Korean Peninsula, Journal of Species Research 6, pp. 227-246 : 238-240

6. Acroperus africanus Neretina and Kotov, 2015

( Fig. 8)

Material deposited to NIBR. 5 parthenogenetic females from Jeongiho Lake (N 38.22814°, E 128.5644°), Gangwon-do, coll. 07 May 2016 by I. Karanovic and T.

Karanovic, NIBRIV0000812491.

Other localities. A shallow pool near road (N 33.43798°, E 126.6961°), Jeju-do, coll. in 27 Nov 2012 by A.A. Kotov and H.G. Jeong; stream near Daecheon river (N 33.43427°, E 126.7516°), Jeju-do, coll. in 26 Nov 2012 by A.A. Kotov and H.G. Jeong .

Parthenogenetic female. Body ( Fig. 8) with a well-expressed dorsal keel, moderately high, ovoid in lateral view, with maximum height before the midline, strongly compressed laterally. Dorsal margin highly arched. Postero-ventral angle with 1-3 small denticles with narrow bases, small setules between the latter ( Fig. 8B, C). Valves with a prominent sculpture as diagonal lines. Head large, head keel moderately developed, distance from eye to anterior margin of keel about 1-1.5 diameters of eye. Three major head pores. Labrum ( Fig. 8D) typical for the genus. Postabdomen ( Fig. 8E) of typical for genus morphology and armature, with distal part of dorsal margin 3-3.5 times longer than preanal one, preanal portion slightly longer than anal one. Antenna I ( Fig. 8F) with lateral aesthetasc as long as antenna I itself, longest terminal aesthetasc significantly longer than antenna I itself. Antenna II ( Fig. 8G) long, about 1/4 of body length. Antennal formula, setae 0-0-3/1-1-3, spines 1-0-1/0-0-1. Branches long and slender, exopod slightly shorter than endopod. Seta arising from proximal segment of endopod short, about 2/3 length of middle segment. Seta arising from middle segment of endopod two times longer than apical segment. All apical setae of similar thickness. Spine on proximal segment of exopod about 1/3 length of middle segment. Apical spines about 1/3 length of apical segments. Limb I (Fig, 8H, I) with inner distal lobe having three setae, seta 1 ( Fig. 8I: 1) claw-like, strongly curved, setae 2 and 3 armed with strong setules in distal portion, seta 1 two times shorter than seta 3, seta 2 slightly shorter than seta 3. Endite 3 with seta 1 ( Fig. 8H: 1) significantly shorter than setae a-c. Endite 2 with seta e almost as long as limb itself, 1.5 times longer, than seta f. Inner seta (2) of endite 2 three times longer than inner seta (3) of endite 1.

Male. In contrast to female ( Fig. 8J), body ( Fig. 8K) without expressed dorsal keel, moderately high, low ovoid in lateral view, with maximum height before the midline, strongly compressed laterally. Eye two times larger than ocellus. Postabdomen moderately long, with almost parallel margins, slightly wider in postanal portion than in preanal ( Fig. 8L). Preanal angle well-defined, preanal angle not defined, distal portion 2.5 times longer than preanal one. Postabdominal claws situated on a small protrusion in middle of distal margin of postabdomen. Spermoducts open above this protrusion, postero-ventral and postero-dorsal angles rounded. Anal and postanal margins with about 12 clusters of short setules, in postanal portion these setules more robust. Lateral clusters of setules same as in female. Postabdominal claw of same shape as in female, significantly longer than preanal portion of postabdomen. Antenna I ( Fig. 8M) wider and longer than in female, with two long lateral aesthetascs and 9 terminal aesthetascs, one of them significantly longer and thicker than others. Male seta located on 1/3 distance from the base, not reaching distal end of antenna I. Limb I ( Fig. 8O, P) with U-shaped copulatory hook, its distal portion almost as long as limb itself. IDL setae 1-3 much thinner than in female, male seta slightly shorter then IDL seta two. Copulatory brush seta small, shorter then first IDL seta. Ventral face of the limb under copulatory brush with a cluster of about 7 short stiff setules, followed by row of about 12 very long setules. About 15 shorter stiff setules along border of endite 3.

Notes. Studied specimens share most diagnostic features of A. africanus (see Neretina and Kotov, 2015). The former differs from its sibling-species, A. angustatus , in: (1) a strongly arched dorsal margin of valves, (2) small, not saw-like postero-ventral denticles of valves, (3) length of seta on basal segment of endopod not exceeding 1/2 length of middle segment, (4) inner seta 3 of limb 1 being about 3 times longer than inner seta 2. Male of A. africanus was never described before. Now we conclud- ed that its morphology is similar to that of A. angustatus (see Sinev, 2009), but differs in the shape of the distal margin of the postabdomen and a smaller number of setules on the anterior face of limb I (below the copulatory brush). Previously, A. africanus was reported from Ethiopia and Republic of South Africa ( Neretina and Kotov, 2015) and then from North-East Thailand (Sinev, 2016). A. africanus is possibly a widely distributed Paleotropical species.

This is a new record for the Korean Peninsula. This taxon should be regarded as a member of the southern thermophilic complex sensu Kotov (2016) and South Korea is the northernmost region of its distribution.