Limnesia (Limnesia) megaseta, Yi, Tianci & Jin, Daochao, 2009

Yi, Tianci & Jin, Daochao, 2009, Water mites of the genus Limnesia Koch, 1836 (Acari: Hydrachnidia, Limnesiidae) from China, with description of four new species, Zootaxa 2234, pp. 21-38 : 29-31

Limnesia (Limnesia) megaseta sp. nov.

Figure 5 , A–L

Type series: Holotype: Male, Hulan River, Yichun City, Heilongjiang Province, 19 August 1996, leg. Jin Daochao. Paratype: Four males and three females, the same data as the holotype. Two males and one female were dissected and slide-mounted.

Diagnosis Glandular sclerites well developed; strong seta on ventral surface of P-II; genital plates somewhat isosceles trapezoid-shaped; postgenial sclerite outstretched and rectangle shaped; genital plates fused anteriorly, separated posteriorly and fused with postgenial sclerite in male; acetabula reduced in size.

Description Male Body soft and smooth, 680 (515) in length, 520 (422) in width; dorsum with a pair of anterior small platelets fused with O2 and a single moderated posterior plate, which 48 in length, 53 in width; A1 with long seta located on dorsal anterior end of body; lateral eyes separated; O1 slightly anterior to anterior-lateral eyes; A2 slightly posterior to posterior-lateral eyes; O2 anterior to D1; infracapitular bay Vshaped, much less than half of median margins of CxI; CxI separated but close to each other; medial margins of CxI 95 in length; ACG, with strong posterior apodemes, near to but separated from PCG; medial margins of CxIII round with secondary sclerotization; distance between CxIII median angles (including the secondary sclerotization) 51 (27); E4 on midland of CxIII, confined to a somewhat triangular area formed by a bifurcation of the suture line between CxIII and CxIV; genital plates fused anteriorly, separated posteriorly and fused with postgenial sclerite; postgenial sclerite rectangle shaped and outstretched; three pairs of small and disc-like genital acetabula; V1 posterior to genital plates; V3 lateral to V1; excretory pore slightly anterior to V2; chelicera as shown in Figure 5 -G, 228 (161) in length, claw 67 (57) in length; proportion and chaetotaxy of palp as shown in Figure 5 -J; P-II stout and distal ventral surface very much inflated, with a well developed seta, 25 (24) in length; ventral side of P-IV with three long hair-like setae in a row and two fine setae; dorsal lengths of P-I to P-V: 18 (19), 78 (81), 60 (63), 108 (115), 28 (29); I-L-5 with two ventral long distal setae; IV-L-6 with four strong and pinnate setae, and a sub-terminal seta, 83 (71) in length; dorsal lengths of I-L-3 to 6: 65 (75), 83 (97), 93 (103), 110 (94); dorsal lengths of IV-L-3 to 6: 115 (121), 133 (154), 175 (181), 163 (171); III-L-4 with 6 (5), III-L-5 with 7 (9), IV-L-4 with 5 (4) and IV-L-5 with 7 (6) swimming hairs.

Female Body soft and smooth, 710 in length, 503 in width; the shape of dorsum and coxae similar to male; medial margins of CxI 110 in length; genital plates (including pregenital sclerite) 175 in length and 131 in width; three pairs of genital acetabula, outer edges of plates concave between first acetabulum and second one, plates with several setae; chelicera 301 in length, chelicera claw 91 in length; the characters of palp similar to male; seta on ventral side of P-II 31 in length; dorsal lengths of P-I to P-V: 15, 88, 63, 113, 38; dorsal lengths of I-L-3 to 6: 57, 106, 116, 110; dorsal lengths of IV-L-3 to 6: 178, 191, 216, 198; III-L-4 with 5, III-L-5 with 8, IV-L-4 with 5 and IV-L-5 with 9 swimming hairs.

Remarks The new species closely resemble Limnesia koenikei Piersig, 1894 , Limnesia koenikei asiatica Marshall, 1928 and Limnesia rimiformis Jin, 1997 . The following morphological characteristics distinguish the new species from above species. PCG is well developed, its posterior ends at the same level with the posterior end of genital plates; genital field is somewhat trapeziform in male; postgenial sclerite rectangle shaped and outstretched; the length of ventral infracapitulum apodeme longer than that of dorsal apodeme; IV-L-6 with a row of pinnate setae. In addition, L. megaseta is similar to Limnesia turgeotrochanter Yi & Jin sp. nov., described in this paper from Xinjiang Province, China. The following morphological characteristics distinguish L. megaseta from Limnesia turgeotrochanter . Posterior dorsal plates are present, a single round plate in male and a pair of oviform plates in female, which are not present in Limnesia turgeotrochanter ; the length of distal setae of I-L-5 is more than 2/3 that of I-L-6 which is only about 1/3 of I-L- 6 in Limnesia turgeotrochanter ; E4 are on midland of CxIII, confined to a somewhat triangular area formed by a bifurcation of the suture line between CxIII and CxIV, while E4 located on anterior margin of CxIII in Limnesia turgeotrochanter .

Etymology Named after its strong peg-like seta on ventral surface of P-II.

Figures

FIGURE 5. Limnesia megaseta sp. nov. A—idiosoma, ventral view, male, B—idiosoma, dorsal view, male, Cidiosoma, lateral view, male, D—idiosoma, ventral view, female, E—idiosoma, dorsal view, female, F—genital field, male, G—lateral view of female infracapitular, H—palp, lateral view, female, I—infracapitular, lateral view, male, Jpalp, lateral view, male, K—IV-L- 5, 6, male, L—I-L- 5, 6, male. Bars = 100 Μm.