Daphnia similoides Hudec, 1991

Popova, Ekaterina V., Petrusek, Adam, Kořínek, Vladimír, Mergeay, Joachim, Bekker, Eugeniya I., Karabanov, Dmitry P., Galimov, Yan R., Neretina, Tatyana V., Taylor, Derek J. & Kotov, Alexey A., 2016, Revision of the Old World Daphnia (Ctenodaphnia) similis group (Cladocera: Daphniidae), Zootaxa 4161 (1), pp. 1-40 : 24-28

Daphnia similoides Hudec, 1991

( Figs 14–16 )

Daphnia similoides Hudec 1991 : p. 10, 15–19, figs 9–11, 20–22, 26b, Plate 1, figs 5–8; Benzie 2005: p. 311–314. Daphnia similis Claus in Venkataraman 1995 : p. 378–385, figs 7–10.

? Daphnia carinata King in Brehm 1950 : p. 23, Fig. 6 a–d.

? Daphnia sarojae Rane, 1986 : p. 640–642, Pl. 2: figs 1–10.

Type locality. " India—Ootacamund or Udagamandalam : Ooty Lake in Nilgiris Mountains at an elevation of 2288 m ; 34 ha, mean depth 3 m. It is highly eutrophic lake, heavy[sic] polluted from Ootacamund" ( Hudec 1991).

Type material. Holotype. A parthenogenetic female, the Natural History Myseum, London, BMNH 191.13.

Paratypes. Many parthenogenetic females on slides, BMNH 191.15–17, 18–22, 25–28 and in tube BMNH 191.29–38; dissected males BMNH 191.23, 24. Few females in the personal collection of S.M. Glagolev (now gifted by him to A.A. Kotov).

Allotype. Male, BMNH 191.14.

Material studied here. India. Populations 11–12 in Table 1 . Ooty Lake in Nilgiris Mountains (N11.405°, E76.688°), Tamil Nadu, coll. in 0 6.07.1984 by I. Hudec (paratypes from the collection of S.M. Glagolev). Tank in Halhita colony, W. of Jabalpur, Hindustan, coll. in 0 5.20.1977 by P. Rane . Pakistan. Pond at Faisalabad, Hindustan, coll. in 0 3.28.1983 by N. Shari.

Short diagnosis. Parthenogenetic female. Body subovoid, body depth/length (without shell spine) = 0.45– 0.63, shell spine is relatively long, a small depression between head and rest of body ( Fig. 14 A). Rostrum elongated, ventral margin of head without a pre-ocular and post-ocular depression, eye capsule located below the level of anteriormost point of head; compound eye relatively small, ocellus present. Head shield with slightly projected, pointed fornices, a projection from valves penetrates to about 1/2 of head shield length ( Fig. 14 B). First abdominal segment with a relatively short (shorter than postabdominal claw) process, almost straight; second segment with a smaller process (two times shorter than firrst process), the third segment with a low, mound-like process; the fourth segment lacking a process, with a convex dorsal margin. Preanal angle of postabdomen not expressed, postanal angle not expressed. On outer side of postabdominal claw, the first and second (proximal) pectens consisting of relatively strong teeth, longest one approximately 1/2 claw diameter; third pecten consisting of numerous fine setules not reaching tip of claw ( Fig. 14 G, H). Body of antenna I well-developed, tips of aesthetascs not projected beyond tip of rostrum, antennular sensory seta arise from base of mound of the antenna I and reaching tip of mound ( Fig. 14 C). On limb I ODL and IDL as in previous species, setae 1–3 long ( Fig. 15 A: 1– 3), bearing short setules, seta 4 two-three times shorter than the former, with short setules distally ( Fig. 15 A: 4). Limb II–IV in general as in other species of this group ( Fig. 15 B–D), only seta 1 ( Fig. 15 B: 1) on limb II longer than in that in D. similis . Limb V with exopodite supplied with a distal setae and a long, curved lateral seta; a very small additional seta in middle of exopodite outer margin ( Fig. 15 E, arrow).

Ephippium. "D"-shaped, shell spine is not incorporated into ephippium, anterior margin of ephippium fluently turned to anterior projection.

Adult male. Body elongated, body depth/length (without shell spine) = 0.47–0.57, rectangular-rounded, dorsal margin of valves almost straight, small depression between head and valves, postero-dorsal angle distinct, with a short caudal spine ( Fig. 16 A). Head with a small, elongated, rounded rostrum, lacking both pre-ocular and postocular depression ( Fig. 16 B). Compound eye not large, does not occupy all anterior part of head. Anterior part of valve ventral margin with a slight projection and then with a slight depression, densely covered by relatively short setae. Abdomen without a low mound on each of its segments. Postabdomen with distal portion as a short tube, dorsal margin almost sraight, gonopore opens subdistally, no genital papilla. Anal teeth on distal portion of anal margin substituted by groups of fine, short setules, sometimes except of distalmost tooth which present in many males ( Fig. 16 F: arrow). On outer side of postabdominal claw, the first and second (proximal) pectens consisting of relatively strong teeth, longest teeth longer than 1/2 claw diameter; third pecten consisting of numerous fine setules not reaching the tip of claw ( Fig. 16 F, E). Antenna I long; antennular sensory seta thin, located sub distally at end of antenna I body; flagellum long, bisegmented, its distal segment setulated in distal half ( Fig. 16 C). ODL of limb I with a large seta and a small, fine seta ( Fig. 16 G–H: ODL); IDL with a bent copulatory hook ( Fig. 16 I), and two setae of very different size (2 and 2'); anterior setae 2, 3 and 4 smaller that these in female and supplied with longer setules ( Fig. 16 G). On distalmost endite of limb II, anterior seta straight and asymmetrically setulated ( Fig. 16 J). Limb V without additional small seta on outer margin of exopodite ( Fig. 16 K: arrow).

Size. Adult females 1.55–1.94 mm, adult males 1.08–1.44 in our material. No size range was given by Hudec (1991).

Distribution. D. similioides is apparently endemic to India and Pakistan.

Comments. Hudec (1991) concluded that D. similoides is widely distributed in tropical Asia, but we did not confirm this conclusion. Although the illustrations of Hudec (1991) appear to be D. similoides , the author's discussion of D. similoides most likely also includes the recently described species D. sinensis .

Baird (1860) described a taxon from India that was morphologically similar to the D. similis group as Daphnia newporti Baird, 1860 . Unfortunately, the description was inadequate and no detailed information was provided for the type locality ( Baird 1860). Unregistered material in the cladoceran collection of the Natural History Museum of London, is labelled as “ Daphnia newporti Baird ” (VK, pesonal observation), but there is no way to confirm that this is Baird’s original material. As we found that only D. similoides Hudec, 1991 is present in India, D. newporti could be a major synonym of the former. But following section 23.9.1 of the ICZN (2000), we may regard D. newporti as a nomen oblitum and D. similoides as a nomen protectum.

There is a chance that this taxon was also earlier described as Daphnia sarojae Rane, 1986 , but the illustrations and the descriptions of Rane (1986) are also of insufficient quality to make taxonomic conclusions.

Figures

FIGURE 6. Daphnia (Ctenodaphnia) sinensis, limbs of the parthenogenetic female from the pond in Vladivostok, Primorsky Territory, Russia. A, limb I. B, limb II. C, limb III. D, limb III. D, limb III, inner-distal portion. E, limb IV. F, limb V. Scale bar denotes 0.1 mm.

FIGURE 14. Daphnia (Ctenodaphnia) similoides, adult parthenogenetic female from the big tank, Janjira sea fort, Maharashtra, India. A, large adult, lateral view. B, head, lateral view. C, rostrum with antenna I. D – F, ventral, postero-ventral and posterior portion of valve margin. G, postabdomen, lateral view. H, postabdominal claw. Scale bar denotes 1 mm (A); 0.1 mm (B – H).

FIGURE 15. Daphnia (Ctenodaphnia) similoides, limbs of the parthenogenetic female from the big tank, Janjira sea fort, Maharashtra, India. A, limb I. B, limb II. C, limb III. D, limb IV. E, limb V. Scale bar denotes 0.1 mm.

FIGURE 16. Daphnia (Ctenodaphnia) similoides, adult male from the big tank, Janjira sea fort, Maharashtra, India. A, large adult, lateral view. B, head, lateral view. C, antenna I. D, distal end of its body. E, postabdominal claw. F, postabdomen, lateral view. G – I, limb I, its outer portion and tip of copulatory hook. J, limb II, anterior and posterior setae on distalmost endite. K, limb I. Scale bar denotes 1 mm (A); 0.1 mm (B – K).