Declinobates tasmanicus, Smit, Harry, 2009

Smit, Harry, 2009, New Australian hygrobatids (Acari: Hydrachnidia: Hygrobatidae), with the description of two new genera and three new species, Zootaxa 2114, pp. 61-68 : 62-63

Declinobates tasmanicus sp. nov.

( Figs. 1–6 )

Type material. Holotype female, Lake Chisholme, Lake Chisholme Forest Reserve, Tasmania, Australia, 41° 0 7.937 S 145° 0 3.952 E, alt. 378 m, 21 March 2008 ( TMAG). Paratypes: same data as holotype, 3 males, 20 females ( TMAG), 2 males, 14 females ( ZMAN).

Description. Female: Idiosoma 510 (454–705) long and 470 (389–583) wide. Dorsum with a pair of elongated muscle attachment plates and three pairs of small muscle attachment platelets ( Fig. 2 ); elongated platelets fused in a number of paratypes. Glandularia of dorsum and ventrum on a small platelet. Gnathosoma not fused with coxal plates, posteriorly with a short triangular projection. First coxal plates separated medially, ending posteriorly in short apodemes. Suture line of third and fourth coxal plates incomplete. Fourth coxal plates rounded medially, posteriorly with a short projection. Glandularia of fourth coxal plates near suture line of third and fourth coxal plates. Genital field with three pairs of acetabula, lying more or less in an arc ( Fig. 1 ). Gonopore (including pregenital sclerite) 138 long. Pregenital sclerite 132 wide, postgenital sclerite 84 wide. Lengths of PI-PV: 22, 92, 46, 98, 35. PIV ventrally with a ridge, with two setae, ventral margin with another seta more anteriorly ( Fig. 3 ). PIV anteromedially with a large, short seta ( Fig. 4 ). PII dorsally with four setae and PIII dorsally with three setae, most anterior seta of these two segments finely serrated. Lengths of I-leg-4-6: 124, 126, 110. I-leg-5 with a long anteroventral seta, other segments of first leg with two long anteroventral setae. Lengths of IV-leg-4-6: 186, 188, 176. IV-leg-5, III-leg-5 and II-leg-5 with two long swimming setae, I-leg-4 with two long, stiff anteroventral setae, I-leg-5 with one anteroventral stiff seta ( Fig. 5 ). Excretory pore partially sclerotized.

Male: Idiosoma 535 (502–535) long and 421 (405–454) wide. Dorsum posteriorly with a muscle attachment plate and three pairs of small muscle attachment platelets. Glandularia of dorsum and ventrum on a small platelet. Gnathosoma not fused with coxal plates, posteriorly with a short triangular projection. First coxal plates separated medially, ending posteriorly in short apodemes. Suture line of third and fourth coxal plates incomplete. Fourth coxal plates rounded medially, posteriorly with a short projection ( Fig. 6 ). Three pairs of platelets posterolateral of fourth coxal plates. Glandularia of fourth coxal plates near suture line of third and fourth coxal plates. Genital field 150 wide and 112 long with three pairs of acetabula, lying more or less in an arc. Gonopore 138 long, anteriorly of acetabula a row of seven small setae. Anteriorly of genital field a rounded pregenital sclerite. Lengths of PI–PV: 22, 79, 38, 86, 34; palp as in female. Lengths of I-leg-4- 6: 118, 116, 102. Lengths of IV-leg-4-6: 168, 176, 150; legs as in female. Excretory pore sclerotized.

Remarks. This is the second Declinobates species, the first one ( D. longmoreae ) was described by K.O. Viets (1984) from Hidden Lake, Fraser Island, Queensland. The new species differs in the glandularia lying on larger platelets (on very small platelets in longmoreae ), the acetabula of the female are lying in an arc (in a triangle in longmoreae females or in a row in males) and the genital field of the female is located posteriorly of the fourth coxal plates, while in longmoreae females the pregenital sclerite is located between the fourth coxal plates.

Figures

FIGURES 1 – 2. Declinobates tasmanicus sp. nov., holotype female. 1) ventral view; 2) dorsal view. Scale bar = 50 µm.

FIGURES 3 – 6. Declinobates tasmanicus sp. nov., holotype female. 3 – 4) palp; 5) I-leg- 4 - 6; 6) paratype male, ventral view. Scale bar = 50 µm.