Litarachna hongkongensis, Smit, 2002

Smit, Harry, 2002, Two new species of the water mite family Pontarachnidae (Acari: Hydrachnidia), with a discussion of the taxonomic status of Pontarachna hinumaensis Imamura, Zootaxa 22, pp. 1-8 : 4-5

Litarachna hongkongensis n. sp.

Figs. 4­8

Material examined

Holotype, female, Starfish Bay, on Serpulidae , Hong Kong, 20 April 1989, leg. I. Bartsch (ZMAN). Paratypes: 3 males, 2 females (ZMAN), 2 males and 2 females (SMF), same data as holotype.

Diagnosis

Ventral margin of PIV with a small tubercle, pre­ and postgenital sclerite of female bowed and almost touching, glandularium­like structure posteriorly of fourth coxal plates separated from accompanying setae.

Description

Female: Body soft, 348 (300­381) long and 300 (251­324) wide. First coxal plates separated medially. Suture line of second and third coxal plates and suture line of third and fourth coxal incomplete. Medial posterior apodemes of fourth coxal plates long, lateral apodemes short. Between these two apodemes a pair of glandularium­like structures, separated from accompanying setae. Genital field located between medial posterior apodemes. Genital field 56 long and 42 wide, pregenital sclerite and postgenital sclerite strongly bowed and almost touching each other. Posteriorly of genital field two pairs of wheel­like acetabula. Dorsal lengths of PI­PV: 20, 74, 28, 90, 30. Ventral margin of PII slightly bowed, ventral margin of PIV with a setal tubercle. Lengths of I­leg­4­6: 48, 66, 70. Lengths of IV­leg­5­6: 104, 104; IV­leg­5 with two swimming setae.

5 Male: Body soft, 348 (316­365long and 251 (284­332) wide. First coxal plates separated medially. Suture line of second and third coxal plates and suture line of third and fourth coxal incomplete. Medial posterior apodemes of fourth coxal plates long, lateral apodemes short. Between these two apodemes a pair of glandularium­like structures, separated from accompanying setae. Genital field located between medial posterior apodemes. Genital field 28 long and 25 wide, sclerotized ring around gonopore with four pairs of setae. Around genital field relatively few (approximately 20) short setae. Posteriorly of genital field two pairs of wheel­like acetabula. Lengths of PI­PV: 15, 76, 26, 86, 30; palp as in female. Lengths of I­leg­4­6: 50, 70, 66. Lengths of IV­leg­4­6: 95, 114, 102. IV­leg­ 5 with two swimming setae.

Remarks

The new species is remarkably similar to the Mediterranean L. duboscqi in the shape of the palp and coxal plates. Differences can be found in the glandularium­like structure posteriorly of the fourth coxal plates, which is fused with the accompanying setae in duboscqi , and separated in the new species. Moreover, the anterior pair of wheel­like acetabula is much more separated in the new species. The palps of the two species are similar. In the holotype the setal tubercle appears smaller compared to L. duboscqi , but paratypes (fig. 8) have PIV similar to that of duboscqi .

Figures

FIGURES 4­6. Litarachna hongkongensis n. sp., holotype female. 4, ventral view; 5, palp; 6, Ileg­4­6. Scale bar 50 Pm.

FIGURES 7­8. Litarachna hongkongensis n. sp., paratype. 7, ventral view (male); 8, palp (female). Scale bar 50 Pm.