Hygrobates (Hygrobates) foreli (Lebert, 1874)

Tuzovskij, Petr V., 2018, Larval morphology of Hygrobates foreli (Lebert, 1874), H. longiporus Thor, 1898 and H. trigonicus Koenike, 1895 (Acari, Hydrachnidia, Hygrobatidae), Zootaxa 4374 (2), pp. 249-262 : 250-254

Hygrobates (Hygrobates) foreli (Lebert, 1874)

( FigS 1–15 )

Material examined. Larvae (n=8) were reared from two femaleS collected in Magadan Province (ASian part of RuSSia): one female 16 AuguSt 1981, Anadyr River near Settlement Markovo, Anadyr DiStrict ; one female 3 July 1982, Pucheveem Stream (inflow of the river Chaun), Chaun DiStrict. The duration of the embryonic period waS 12–15 dayS.

Diagnosis. Larva. DorSal plate elongated with parallel lateral marginS; Setae Fch longer than Vi; tmas on coxae III abSent; excretory pore with muScle attachment ScarS anteriorly, excretory pore and Setae Ae forming right tranSverSe row; Setae Pi and Pe equal in length; II-Leg-3 with two heavy Setae; III-Leg4 with three heavy Setae; IIleg-5 Solenidion located dorSoproximally to middle of Segment.

Description. DorSal plate elongate (L/W ratio 1.35–1.65), in unengorged larvae covering large part of dorSum ( Fig. 1 ), with Straight lateral marginS, anterior margin Straight, poSterior end narrowed and rounded, Simple Setae long and thick, but Setae Fch longer than Vi, trichobothria Fp, Oi thin, Short and equal in length. Eight pairS of Setae (Oe, Hi, He, Sci, Sce, Li, Le, Si) Situated in Soft membrane, Oe longeSt, Hi and Sci Shorter than Oe but longer than other Setae Situated in the membrane.

Both pairS of Setae on coxae I (C1, C2) relatively Short, thin and equal in length ( Fig. 2 ). Lateral Setae (C3) on coxae II and medial Setae (C4) on coxae III long, thick and approximately equal in length. TranSverSe muScle attachment Scar on coxae III abSent. UrStigma relatively large, oval. All coxae with reticulated patternS conSiSting of elongated cellS. Setae Ci ( Fig. 3 ) very long, well thickened, on moderately long projection. Excretory pore plate wider than long (L/W ratio 0.39–0.41), Slightly convex anteriorly, “W” — Shaped poSteriorly and with muScle attachment ScarS anteriorly; excretory pore located in the center of plate between baSeS of Setae Ae, baSeS of Setae Ai located cloSe to anterior margin; diStance between baSeS of Setae Ae–Ae almoSt two timeS longer than diStance between Ai–Ai.

BaSal SegmentS of chelicerae fuSed to each other medially ( Fig. 3 ), with Slightly convex lateral marginS, their anterior edgeS concave. Chela Small, creScent–Shaped with two minute Subapical teeth ( Fig. 4 ).

PedipalpS compact ( Fig. 5 ): P–1 very Short, without Setae; P–2 relatively large, with Single dorSal Seta diStally middle of Segment; P–3 with a very long, thick lateroproximal Seta and Short, thin dorSodiStal Seta; P–4 with long lateral Seta and Short dorSal one and a maSSive dorSodiStal claw; P–5 Small, with one rather long Solenidion and unequal Simple Setae, one of them very Short.

Shape and arrangement of Setae on legS SegmentS aS Shown in FigS 6–8 . Number of thickened Setae from trochanter to tarSuS: I-Leg: 1, 1, 1, 0, 0; II-Leg: 0, 1, 2, 1, 0; III-Leg: 0, 1, 3, 3, 0. II-Leg-1 and III-Leg-1 each with long Seta. Solenidion on I-III-Leg-3 each Subequal in length, both diStal Solenidia on I/II-Leg-4 and Solenidion on III-Leg-3/4 Subequal in length; I-Leg-5 with Short, thick dorSodiStal Solenidion, and II-Leg-5 with comparatively long, thin dorSoproximal one. ClawS of legS III ( Fig.10 ) larger than clawS of legS I and II ( Fig. 9 ). Central claw and lateral clawS in all legS nearly Subequal in Size.

MeaSurementS, n=8. DorSal plate L 280–310, W 175–200; Setae Fch L 45–50, Fp and Oi L 15–20, Vi L 38–40, Oe L 60–70; Hi and Sci L 55–65, He and Sce L 40–50; Li, Le and Si L 38–45, Se L 30–40, Ci L 160–175, Pi and Pe L 25–30, Setae C1 and C2 L 21–26, C3 L 48–58, C4 L 65–75; medial marginS of coxae I–III L 198–202; urStigma L/H 19–22/12–14; excetory pore plate L 41–45, W 105–110; capitulum L 95–100; baSal SegmentS of chelicera L 73–80, chela L 22–26; pedipalpal SegmentS (P-1-5) L: 3–5, 32–35, 18–22, 6–7, 5–6; legS SegmentS L: I-Leg-1-5: 25–35, 35–40, 38–40, 47–50, 54–58; II-Leg-1-5: 32–45, 38–42, 38–40, 53–58, 64–68; III-Leg-1-5: 41–45, 41–49, 48–50, 60–65, 73–80.

Female. Integument Soft and finely Striated. All idioSomal Setae thin and approximately equal in length, but Setae Fch ( Fig. 11 ) longer and much thicker than otherS idioSomal Setae. Anterior coxal plateS with Short apodemeS, poSteromedial margin uSually broadly rounded. Coxal plate IV trapezoidal with rounded medial margin ( Fig. 12 ). Genital plateS ( Fig. 13 ) triangular, aS long aS or Slightly longer than gonopore, medial margin Slightly indented near the centre; acetabula large, ac-2 and ac-3 on the Same level. Pedipalp ( Fig. 14 ) moderately long; P-1 with Single dorSodiStal Seta; P-2 with Six dorSal Setae, ventral margin concave, with a Short diStoventral projection covered by denticleS, P-3 with four thick and one thin dorSal Setae, ventral margin convex, with denticleS covering it diStal half; P-4 ventral Setae cloSe to each other near middle of Segment. I-Leg-4/5 with two Subequal relatively long diStoventral Setae ( Fig. 15 );

MeaSurementS (n=9). IdioSoma L 800–1250; Setae Fch L 60–70; coxal plateS I + capitulum mL 165–180; genital plateS L 180–230, W 95–140, genital acetabula (ac-1-3) L/W 85–90/60–80, 100–150/50–55, 100–150/60– 65; cheliceral SegmentS L: baSe 225–245, chela 120–145; pedipalp SegmentS (P-1-5) L: 38–42, 135–165, 115–130, 165–195, 57–65; leg SegmentS L: Leg-1-6: 70–90, 135–165, 155–175, 210–245, 225–255, 210–240; II-Leg-1-6: 75– 85, 135–165, 160–190, 235–260, 250–285, 225–255; III-Leg-1-6: 85–100, 145–175, 195–215, 270–310, 285–330, 280–290; IV-Leg-1-6: 210–230, 195–230, 245–285, 335–395, 330–410, 285–330.

Remarks. The morphology of the larva deScribed by WainStein (1980) aS H. foreli (Lebert, 1874) iS in perfect agreement with the deScription of the larva H. longiporus (See deScription below).

Figures

FIGURES 1–2. Hygrobates foreli (Lebert, 1874), larva: 1, dorsal view; 2, ventral view. Scale bar:50 µm.

FIGURES 3–10. Hygrobates foreli (Lebert, 1874), larva:3, chelicera, dorsal view;4, chela, lateral view; 5, pedipalp; 6, Leg I; 7, Leg II; 8, Leg III; 9, claws of leg I; 10, claws of leg III.Scale bars:3, 5, 6–8 = 50 µm, 4, 9–10 = 20 µm.

FIGURES 11–15. Hygrobates foreli (Lebert, 1874), female:11, seta Fch; 12, coxal plates I–IV, ventral view; 13, genital field; 14, pedipalp; 15, I-Leg-4-6.Scale bars: 11, 14 = 50 µm, 12 = 200 µm, 13, 15 = 100 µm.