Limnesia (Limnesia) undulata ( Müller, 1776 ), Muller, 1776

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 : 33-37

Limnesia (Limnesia) undulata ( Müller, 1776)

Figure 9 , A–M

Material examined Four males and fifteen females from everglade, suburb of Sifeng County, Jiamusi City, Heilongjiang Province, 17 August 1997, leg. Jin Daochao. Two males and four females were dissected and slide-mounted.

Description Male Body soft and smooth, 1090 (1094) in length and 902 (781) in width; dorsum with a pair of small anterior platelets fused with O2 and a single moderated posterior plate, which 84 in length, 67 in width, posteriorly between D2; A1, with short and stout seta, on the anterior end of body; O1 posterior to A1; lateral eyes separated, anterior lateral eyes posterior to O1, posterior ones anterior to A2; O2 fused with small plates anterior to D1; infracapitular bay U shaped, longer than median margins of CxI; medial borders of CxI connected by a bridge of secondary; ACG with moderated posterior apodemes; E2 fuse to CxIII; medial margins of CxIII round with small secondary sclerotization; distance between CxIII median angles (including the secondary sclerotization) 40 (54); suture line between CxIII and CxIV incomplete, ending at E4; genital plates fused and somewhat round with slightly secondary sclerotiztion, 201 (203) in length and 223 (201) in width (including the secondary sclerotization); genital plates bearing a number of setae around acetabula; Three pairs of small and conus-shaped acetabula on genital plates; gonopore slightly posterior to the first acetabula; V1, V3 and second actabula at the same level; excretory pore located between V2; dorsal lengths of P-I to P-V: 36 (52), 275 (283), 145 (153), 401 (410), 85 (85); Figure 9 -H illustrating the proportion and chaetotaxy of the palp; dorsal setae of palp stocky; the tubercle, 42 (44) in length, on the ventral palpal segment longer than its peg-like seta which 21 (15) in length; chelicera 446 (470) in length, chelicera claw 124 (140) in length Figure 9 -F illustrates the chelicera; I-L-5 with two short terminal setae, dorsal lengths of I- L-3 to 6: 104 (195), 211 (215), 276 (268), 194 (263); IV-L-6 with four strong setae, and a sub-terminal seta, 105 (128) in length; dorsal lengths of IV-L-3 to 6: 249 (200), 358 (365), 421 (403), 449 (458); legs with a pair of simple hooked claws; III-L-4 with 0 (4), III-L-5 with 8 (7), IV-L-4 with 4 (5) and IV-L-5 with 8 (8) swimming hairs.

Female Body soft and smooth, 1691 (1613/1638/1538) in length, 1298 (1301/1313/925) in width; the shape of dorsum and coxae similar to male; distance between CxIII median angles (including the secondary sclerotization) 198 (45/171/149); genital plates (including pregenital sclerite) 281 (278/278/280) in length and 201 (203/205/200) in width; pregenital sclerite well developed as shown in Figure 9 -D; dorsal lengths of P-I to P-V: 44 (50/45/40), 325 (293/300/300), 196 (198/200/183), 493 (468/475/495), 101 (75/60/95); Figure 9 -I illustrates the proportions and chaetotaxy of the palp; the tubercle, 49 (72/47/60) in length, on the ventral side of P-II longer than its peg-like seta which is 25 (16/14/13) in length; I-L-6 and II-L-6 with a pair of simple hooked claw, however, claw of III-L-6 stronger and with a slender dorsal clawlet and a ventral thick clawlet; IV-L-6 with five strong setae in a row, and a subterminal seta, 131 (115/77/83) in length; dorsal lengths of I-L -3 to 6: 201 (195/195/194), 246 (220/218/215), 296 (293/293/285), 264 (250/270/240); dorsal lengths of IV-L- 3 to 6: 249 (255/255/250), 421 (375/368/380), 472 (455/443/445), 481 (453/460/365); III-L-4 with 0 (0/0/0), III-L-5 with 8 (10/8/6), IV-L-4 with 4 (4/4/4)and IV-L-5 with 8 (10/10/9) swimming hairs

Remarks Limnesia undulata ( Müller, 1776) is a common Palaearctic species. Uchida (1941) and Uchida & Imamura (1951) reported the species without description from China. The specimens in this study were collected from Heilongjiang Province, which belongs to Palaearctic region yet. There are some differences, such as shape of dorsal setae on P-II, ratio distance ventral setae P-IV to proximal and distal margin, number of setae between Ac1 and Ac2, among the Chinese specimens and other Palaearctic region specimens. Fore example, in the Chinese specimens, dorsal setae on palp are small; ratio of distance ventral setae P-IV to proximal and distal margin is 1.05–1.26, the numbers of small setae between Ac1 and Ac2 are 3–5 on the left and 4–6 on the right in male, while in Netherlands specimens ( Davids 1997), dorsal setae on palp are long; the ratio is 1.5; the number of setae between Ac1 and Ac2 are 7 on the both sides in male.

Figures

FIGURE 9. Limnesia undulata (Müller, 1776). A—idiosoma, ventral view, male, B—idiosoma, dorsal view, male, C – idiosoma, ventral view, female, D—genital field, female, E—genital field, male, F—chelicera, lateral view, male, Ginfracapitular, lateral view, male, H—palp, lateral view, male, I—palp, lateral view, female, J—I-L- 5,6, female. K—III- L- 6, female, L—IV-L- 5, 6, female, M – IV-L- 5, 6, male, Bars = 100 Μm.