Daphnia (Ctenodaphnia) inopinata, 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

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 : 28-31

Daphnia (Ctenodaphnia) inopinata sp. nov.

( Figs. 4 D, 17–18)

Daphnia similis -like cladoceran in Petrusek 2003: p. 12.

Etymology. From Latin “inopinatus” = “unexpected”, referring to its unexpected finding in a suburb of a major metropolitan area.

Type locality. Germany. Ponds in moorland northeast of the Fürst-Wrede-Kaserne barracks (Fröttmaninger Heide), Fröttmaning, Munich (N48.22°, E11.61°; altitude about 500 m).

Type material. Holotype. Adult male, deposited at the collection of the Natural History Museum, London, U.K., NHMUK 2015.2924 .

Paratypes 10 parthenogenetic females, NHMUK 2015.2926-2935 . 1 male, 5 females, Zoological Museum of M.V. Lomonosov Moscow State University, MGU Ml-144 ; 1 male, 7 females and 16 ephippia, personal collection of A.A. Kotov, AAK M-2610.

Allotype. Parthenogenetic female, NHMUK 2015.2925.

Other material studied. Some specimens from the type locality were used for genetic ivestigations and not saved.

Short diagnosis. Parthenogenetic female. Body subovoid, a slight depression between head and rest of body ( Fig. 17 A). Rostrum short, sharp, ventral margin of head without pre-ocular and post-ocular depressions, eye capsule located below the level of anteriormost point of head; ocellus present, bur minute. A projection from valves penetrates to about 1/3–1/2 of head shield length ( Fig. 17 B). On outer side of postabdominal claw, the first and second (proximal) pectens consisting of relatively strong teeth, longest members approximately two times shorter than claw diameter; last tooth of the first pecten larger than others and additionally reinforced; third pecten consisting of numerous fine setules not reaching the tip of claw ( Fig. 17 D, E). Tips of aesthetascs not projected beyond tip of rostrum ( Fig. 17 B). On limb I setae 1–3 long, bearing short setules, seta 4 shorter than the former, with short setules ( Fig. 17 F). Limb II–V as in other species of this group ( Fig. 17 G).

Ephippium. "D"-shaped, shell spine is not incorporated into ephippium ( Fig. 4 D).

Adult male. Body rectangular-rounded, a shallow depression between head and valves ( Fig. 18 A). Head with a short rounded rostrum, lacking pre-ocular depression and almost lacking a post-ocular depression. Compound eye relative small, optical vesicle does not occupy whole anterior part of head ( Fig. 18 B). First abdominal projection reduced, second projection small. Anal teeth present only in basal part of anal region, in anterior portion they are substituted by group of thin, short setules. On outer side of postabdominal claw, the first and second (proximal) pectens consisting of relatively strong teeth, last tooth of the first pecten is larger than others ( Fig. 18 E, F). Antenna I long, antennular sensory located distally on end of antenna I body; flagellum long, bisegmented, its distal segment setulated ( Fig. 18 C). On limb I anterior setae 2, 3 and 4 smaller that these in female and supplied with longer setules ( Fig. 18 H–J). Limb V with a small additional seta on distal portion of exopodite ( Fig. 18 K).

Description. Adult parthenogenetic female. General. Body almost transparent, body depth/length (without shell spine) = 0.54–0.65, subovoid in lateral view, with maximum height in middle of valves, a shallow depression between head and rest of body, dorsal margin somewhat convex. Postero-dorsal angle in adults with a relatively short caudal spine, ventral margin regularly convex ( Fig. 17 A).

Head with a relatively short, sharp rostrum; posterior margin of head with a low mound in the basal part, prerostral fold absent; ventral margin of head without any pre-ocular and post-ocular depressions, valve dorsal contour lies somewhat above head. Compound eye relatively small, ocellus distinct, although minute, located closer to the compoun eye than to base A1. Head shield with slightly projected, blunt fornices, a projection from valves penetrates to about 1/3–1/2 of its length ( Fig. 17 B).

Carapace slightly convex dorsally, free edge uniformly convex. spinules present on whole dorsal margin and on posterior half of ventral margin. A group of relatively long setae in middle of ventral margin submarginally, short setae present on the postero-ventral edge of valve, setules between them absent ( Fig. 17 C).

Abdomen relatively short, consisting of four segments, the first (basalmost) abdominal segment with a relatively short (somewhat longer than postabdominal claw) process, slightly bent forward; second segment with a small (shorter than postabdominal claw) process bent backward, the third segment with a very low, mound-like process, covered by transverse rows of minute setules; the fourth segment without a process.

Postabdomen tapering distally, with ventral margin straight. Preanal margin almost straight, with series of minute setules. Preanal and postanal angle not expressed. Anal teeth not numerous, slightly curved. Postabdominal setae approximately equal to length of preanal edge, their distal and proximal segments are almost identical. Postabdominal claw is slightly bent, with a pointed tip. Three pectens on its inner sides. The first and the second pectens are composed of longer teeth, with the longest members approximately two times shorter than claw diameter, last tooth of the first pecten larger than others and additionally reinforced; the third pecten consists of thin short setules and that fail to reach the tip of the claw ( Fig. 17 D–E).

Antenna I is a conical tubercle with nine terminal aesthetascs and tips not projecting beyond tip of rostrum, antennular sensory seta arises from base of mound of the antenna I and reaching tip of mound ( Fig. 17 B).

Antenna II relatively long, length of apical setae approximately equal to the length of the branches. Antenna formula: setae1–1–3 / 0–0–1–3.

Limbs I–V, as in D. similoides .

Ephippium. "D"-shaped, shell spine is not incorporated into ephippium ( Fig. 4 D).

Adult male. General. Body elongated, body depth/length (without shell spine) = 0.44–0.45, rectangularrounded. Dorsal margin almost straight, slightly elevated above head; shallow depression between head and valves; postero-dorsal angle distinct, with a short caudal spine; posterior margin almost straight; postero-ventral angle broadly rounded, ventral margin with a depression in middle and a projection in anterior portion. spinules cover only posterior half of dorsal and ventral valve margin ( Fig. 18 A, C).

Head rounded, with a short rounded rostrum, convex ventral margin, lacking pre-ocular depression and almost lacking a post-ocular depression. Compound eye relatively small, optical vesicle does not occupy whole anterior part of head, ocellus small ( Fig. 18 B).

Carapace. Ventral edge with a projection in anterior portion, bearing mumerous, relatively long setae, then a small depression, also supplied by somewhat shorter setae. On postero-ventral portion, shorther setae without setules between them.

Abdomen. First abdominal projection reduced; second projection small; third and fourth reduced.

Postabdomen with a straight dorsal margin; ill-defined preanal angle and smooth postanal angle; distal portion as a short tube; dorsal margin almost straight in preanal region; gonopore opens subdistally, on a reduced genital papilla. Anal teeth present only in basal part of anal region, in anterior portion they are substituted by group of thin, short setules. Postabdominal claw thick, with a pointed end. The first two pectens on postabdominal claw consist of long teeth. First tooth of the first pecten particularly strong ( Fig. 18 E–G).

Antenna I long, somewhat widening distally, without denticles distally near aesthetascs. Nine aesthetascs short. Antennular sensory setae located distally on end of antenna I body, the former shorter than aesthetascs. Length of flagellum about half body length of the antenna I. The distal segment of flagellum is covered with short setules ( Fig. 18 D).

Antenna II relatively larger as compared with female.

Limb I. ODL large, bearing a short seta and a very large seta, supplied with minute setules distally; IDL with a bent copulatory hook, and two setae of very different size; in contrast to female, setae 2, 3 and 4 shorter than those in female and supplied with long, fine setules ( Fig. 18 H–J).

Limb V. In general as in female, but there is an additional (third) small seta on exopodite ( Fig. 18 K).

Size. Adult females 1.54–2.2 mm, adult males 1.19–1.38 mm.

Distribution. Daphnia (Ctenodaphnia) inopinata sp. nov. is known from pools in a single area of a military training ground in Germany.

Comments. At this moment little information is available on the geographic range of this species. Considering that no other locality of this taxon has been so far discovered in Central Europe, the species could have been recently introduced to Germany by anthropogenic activities (as discussed in Petrusek 2003). But it could also be a specific European lineage that eluded discovery, as with D. hrbaceki Juračka, Kořínek & Petrusek, 2010 . Small pools attracted less attention of European hydrobiologists as compared to large lakes.

Differential diagnosis. Taxonomically informative morphological differences among females of the D. similis group remain undetected. Therefore, only males are useful for the differentiation of species. Males of D. inopinata sp. nov. have anal teeth on postabdomen reduced in size and number (in contrast to D. similis s. str.), compound eye relatively small, and anteriormost portion of head without a dome (in contrast to D. sinensis ), distalmost anal teeth minute and additional seta on exopodite V present (in contrast to D. similoides ).

Figures

FIGURE 4. Ephippia of Daphnia (Ctenodaphnia) similis from pond near village of Orly, Volgograd Area, European Russia (A – B); D. sinensis from a road-side cattle pool near Stanitsa Petrovskaya, Krasnodar Area, European Russia (C); D. inopinata sp. nov. from a pond in Fröttmaning, München, Germany (D). Scale bar denotes 1 mm.

FIGURE 17. Daphnia (Ctenodaphnia) inopinata sp. nov. parthenogenetic female from a pond in Fröttmaning, München, Germany. A, large adult, lateral view. B, head, lateral view. C, armature of postero-ventral margin. D, postabdomen, lateral view. E, postabdominal claw. F, limb I. G, limb V. Scale bar denotes 1 mm (A, D); 0.1 mm (B – C, E – F).

FIGURE 18. Daphnia (Ctenodaphnia) sp. nov., male female from a pond in Fröttmaning, München, Germany. A, large adult, lateral view. B, head. C, postero-ventral margin. D, antenna I. E – F, postabdomen. G, postabdominal claw. H – J, limb I, distal portion of its outer distal lobe and tip of copulatory hook. Scale bar denotes 1 mm (A); 0.1 mm (B – K).