Diaphanosoma bopingi, Guo, Fei-Fei & Dumont, Henri J., 2014

Guo, Fei-Fei & Dumont, Henri J., 2014, Relict populations of Diaphanosoma (Cladocera: Ctenopoda) in the Chadian Sahara, with the description of a new species, Zootaxa 3856 (1), pp. 135-142 : 138-140

Diaphanosoma bopingi sp. nov.

(Figs. 4,5)

Etymology. The species is named in honour of Prof Dr Bo-Ping Han, director of the institute of Hydrobiology of Jinan University, Guangzhou, China, in appreciation of his tireless efforts to develop and expand limnology in southern China and beyond.

Type locality. Lake Bokou, Ounianga Serir, 18° 54’ 54’ N, 20° 29’ 46” E, 0 6 March 2014.

Type material. Holotype. An undissected female mounted in glycerol on a glass slide, deposited at National Zoological Museum of China, Institute of Zoology, Chinese Academy of Sciences ( IZCAS), Beijing, accession number DIP 1 and a paratype accession number DIP 2.

Paratypes. Eight dissected and undissected females, one per glass slide, mounted in the same manner as the holotype, and deposited in the Smithsoniam Institution, Washington, accession numbers 1231545 through 1231548, and the Moscow University Museum, accession numbers MGU MI 129 through MGU MI 132.

Diagnosis. A medium-sized Diaphanosoma with small head and small eye; spine on the apex of the basal segment of the two-segmented branch of A2 small; anterior half of valves lightly infolded, posterior half with marginal spines separated in groups by delicate filaments. Posterior spine of valves single, robust. P6: apex of exopodite with three equally long setae. Endopodite with five setae apicad of hard chitin hillock. Postabdominal end-claw with four spines.

Description. Female. Habitus typical of a Diaphanosoma , with a rather small head and a small eye ( Fig. 4 a). First and second antenna e typical in general shape. Second antenna (A2) robust, the basipodite with a plumose seta and a rather small and slender apical spine (not reaching and extending beyond the free margin of the segment), the basal segment of the two-segmented branch with a rudimentary spine (arrow), while other segments have spines of the usual size for the genus ( Figs. 4 B and 5). Seta formula of A2= 4-8/0-1-4

Postabdomen elongate, with general shape as for genus. End-claws with four basal spines ( Fig.4 C, Fig 5 C–D) and single external pecten, the spines of which do not protrude beyond the margin of the claw. Inner surface of the claws smooth (Fig 2A). Dorsum of the postabdomen rather fleshy, wide, flat and smooth. Flanks with lines of spinules that, on inspection by SEM, belong to a J-shaped belt that arises from the base of the last spine, apparently with a slit shaped opening (arrow on Fig 2A) and runs up to the very base of the end-claw ( Fig. 5 C–D).

Valves with a single dorso-posterior spine, rather robust in shape ( Fig. 4 D). Ventral margin of valves gently inflexed, anteriorly with a row of 12–17 long plumose setae, abruptly being replaced by marginal spines. These spines mostly in pairs of similar size, rarely three, and all groups of spines separated by fine filaments, about 16 in number ( Fig. 4 F, G). At about filament 11, the spines become smaller but more numerous, 6–7 per interval between two filaments, and finally, somewhat below the dorsal spine, the filaments cease and the small spines continue as a single row.

Trunk limbs 1–5 in general structure and appearance as for genus. 1th exopodite (apical+lateral setae)=5+5, 2th exopodite (apical+lateral setae)=7+4, 3th exopodite (apical+lateral setae)=7+4, 4th exopodite (apical+lateral setae)=7+4, 5th exopodite (apical+lateral setae)=6+3, 6th exopodite (apical+lateral setae)=5+1. P6 with six setae on the exopodite, the apicalmost three of which are of similar length. Endite with five setae between its apex and a hard chitin hillock ( Fig 4 H). Further basal, another two plumose setae on the endopodite and, finally, a gnathobase with, again, two plumose setae. Endopodite of P6 therefore altogether with 9 setae.

Size. Body length 0.80–0.93 mm (n=10). Diameter of head 0.31 ± 0.03 mm, head to body ratio 0.35.

Differential diagnosis. Having four basal spines on the postabdominal claw instead of three is a unique trait within the genus, and will separate this species at once from all its congeners. Also unique and thus diagnostic if combined are the rudimentary spine on A2, and the number and arrangement of spines and filaments along the ventral valve margin.

Figures

FIGURE 4. Diaphanosoma bopingi sp. nov. from Lake Bokou, Ounianga. A, Head and antennae. B, Swimming antenna (square: zone shown on the SEM micrograph of fig 5 A). C, Postabdomen. D, Postero-dorsal spine of valves. E, Anterior half of ventral valve margin with long plumose setae a = anterior, p = posterior). F, Posterior part of ventral valve margin with large spines and filaments. F, Enlarged anterior section of F. H, Trunk limb 6 (P 6).

FIGURE 5. SEM micrographs of Diaphanosoma bopingi sp. nov. A, A 2 showing short spine on basal segment of exopodite and ‘ normal’ spine on endopodite. B, small spine on exopodite, enlarged. C, Dorsal view of postabdomen (end-claws somewhat distorted) showing four spines on the end-claw, a smooth dorsal plate, and two lateral J-shaped spinulated belts; arrow: slitshaped opening of the belt at its end on the dorsum of the end-claw. D, Enlargement of the former, showing the slit-shaped apex of the spinulated belts, flanking the anus.