Kurzia (K.) cf. media Birge, 1879

Díaz, Analía R. & Adami, Mariana L., 2024, First record and redescription of Kurzia cf. media Birge, 1879 in Argentina, Spixiana 47 (1), pp. 29-33 : 30-32

Kurzia (K.) cf. media Birge, 1879 Fig. 2A- G

Material examined. 3 parthenogenetic females deposited in the Carcinological Collection at Museo de La Plata, Argentina (MLP-Cr 27356).

Fig. 2. Kurzia cf. media . A. Carapace lateral view; B. A2; C. P1; D. P2, scraping spines; E. P3; F. P4; G. post-abdomen. Scale bars A- G: 0.1 mm.

Description

Adult parthenogenetic female. General habitus (Fig. 2A- G), length= 0.9 mm, height= 0.7 mm.

Carapace (Fig. 2A) lacking ornamentation. Subrectangular, laterally strongly compressed, dorsal margin curved and decreasing to the truncated posterior margin, ventral margin slightly concave. Valve setae ca. 30-40 in three main groups, the anterior being the longest. The posterior group with fine setules gradually decreasing in size towards the corner. Transparent brownish.

Cephalic structures. Ocellus smaller than eye, equidistant between rostrum and eye. Head small. Rostrum short. Three circular connected head pores, all the same size, close to the broadly rounded round posterior head shield margin. Labrum short, roughly sub-triangular. Antennules/A1 short, about 2 -2.5, as long as wide, setulated on the margin (four to five rows). Aesthetascs of similar length projecting well beyond the tip of the rostrum, two slightly longer, all implanted on the apex (not illustrated due to damaged antennule). Second antennae/A2 (Fig. 2B). Exopodite not preserved. Only segments of endopodite are illustrated. First endopod segment short. Second segment seta as long as terminal setae, third segment seta shorter. Terminal spine reaching half of terminal segment. Terminal setae of similar thickness.

Thoracic structures. Five pairs of thoracic limbs (P1-5). First limb/P1 (Fig. 2C). Short round epipodite. First endite with just two smooth setae, second endite with three setae, two equal and one shorter, third endite with four similar setae. IDL with two long setae implanted with fine setules unilaterally on distal halves, both similar in size uniformly set. ODL with one slender smooth seta. About six anterior setulae groups with relatively short setules in each group, strongly decreasing in length ventrally. Second limb/P2 (Fig. 2D). Exopodite quadrangular. Eight scrapers, scraping spines gradually decreasing in size between the exopodite and the gnathobase. Two first scrapers relatively longer, third slightly shorter than the fourth, sixth to eighth slightly thicker. Setulation of all scrapers uniform, no anterior elements at the base of scrapers. Gnathobase with short tuft of setules and a filter comb (not illustrated because of the damaged gnathobase). Third limb/P3 (Fig. 2E). Epipodite oval-rectangular with short projection. Exopodite circular with seven setae in 2 +5 arrangement. First seta about twice as long as second, both in opposite directions; third seta about twice as long as sixth seta; fourth seta just shorter than sixth, fifth of the same length as the seventh seta and both are half as long as the sixth seta. Fourth seta clearly bent in the middle, oriented away from the epipodite. All setae widely plumose. Endopodite with 7 plumose setae, three subequal (DS-3) setae. Seven gnathobase filter setae. Fourth limb/P4 (Fig. 2F). Pre-epipodite round. Exopodite round, with six plumose setae; first seta slightly shorter than second and third which are of similar lengths; fourth to sixth setae shorter and finely setulated. Fifth limb/P5 not observed.

Abdominal/postabdominal structures.Postabdomen (Fig. 2G).Widest at preanal corner.length of postabdomen 2-2.5 times as long as wide. Distal corner of post-abdomen forms lobe not projecting beyond terminal claw base with a cluster of 1-3 denticles on tip. About nine groups of isolated marginal denticles. Terminal claw (Fig. 2G).Long,about 0.10 mm.Curved distally, with a single basal spine twice as long as basal diameter of terminal claw, basal spine without serrations. Concave margin of the claw with fine setules.

Ephippial female and ephippium. Ephippial female (Fig. 2A) light brown colour. Ephippium light to dark brown with a single egg, as for the genus.

Males. Not found.