Hydryphantes dispar (Schaub, 1888)

Tuzovskij, Petr V., 2014, Larval morphology of Hydryphantes clypeatus Thor, 1899, H. dispar Schaub, 1888 and H. planus Thon, 1899 (Acari, Hydrachnidia: Hydryphantidae), Zootaxa 3869 (2), pp. 131-142 : 135-138

Hydryphantes dispar (Schaub, 1888)

( Figs 17–31 )

Material examined. Larvae (n = 13) were reared from a single female collected in a sedge bog near village Koltsovo, Stavropol District, Samara Province, 5 May 1998, leg. P.V. Tuzovskij. The duration of the embryonic period was 15 days.

Diagnosis. Distance between bases of trichobothria Oi larger than their length; setae Hi, Sci and Li longer than Oe, He, Sce and Le; excretory pore plate usually as long as wide or slightly longer than wide; urstigma wider than long; posterior margin of coxal plate II straight; P-5 with long solenidion; I–II-Leg-4 solenidia 2.0–2.5 times longer than eupathidia; I–II-Leg-5 with subequal solenidia; I-Leg-6 de longer than ds.

Description. Larva. Colour red. Idiosoma oval, anterior pair of platelets triangular or oval, trichobothria Fp long and slightly extending beyond posterior margin dorsal plate ( Fig. 17 ). Posterior plate anteriorly narrow, posteriorly widening; median eye rather large and situated between rows of setae Vi and Oi; seta Vi thick and slightly longer than Fch; Oi short, distance between Oi-Oi larger than their length. Medial dorsal setae (Hi, Sci and Li) a little longer than lateral setae (Oe, He, Sce and Le).

Coxal plates II small, coxal plates I and III large, more or less trapezoidal and rounded medially ( Fig. 18 ); all coxal setae relatively short and subequal. Urstigma oval, wider than long, moderate in size. Setae Si longer and thicker than other ventral idiosomal setae. Setae Se, Ci, Pi and Pe subequal and slightly longer and thicker than both pairs of anal setae. Excretory pore plate small, usually as long as wide or slightly longer than wide ( Figs 19–20 ), excretory pore situated near posterior margin of plate. Bases of setae Ae situated anterior to excretory pore.

Chelicera with large basal segment and small stylet. Basal segment ( Fig. 21 ) with moderately narrow strips.

Pedipalps stout ( Fig. 22 ): P-1 short, without seta; P-2 large with convex dorsal margin and a single dorsal seta in proximal part; P-3 with two subequal setae (proximal and distal); P-4 with three thin nearly subequal setae and a large dorsodistal bifurcate claw with two unequal clawlets; P-5 small with rather long solenidion, five long, thick and two short, thin setae.

Legs 6-segmented. Shape and arrangement of specialized setae on terminal legs segments as shown in Figs 23–25 . I–II-Leg-4 solenidia 2.0–2.5 times longer than eupathidia, I–II-Leg-5 both proximal solenidia approximately equal in length, I-Leg-6 eupathidium short and situated distal to solenidion basis; II-Leg-6 solenidion proximal, eupathidium is submedial; III-Leg-4 proximal solenidion slightly longer than III-Leg-5 proximal solenidion. Empodium large and crescent-shaped on all tarsi, ambulacra short and thin ( Fig. 26 ).

Measurements, n = 10. Dorsal plate L 41–47, W 43–48; setae Fch L 18–23, setae Fp L 43–48, setae Vi L 21–27, setae Oi L 10–13, distance between setae Vi– Vi 40–46, distance between setae Oi–Oi 17–21; setae Hi, Sci, Li, Si L 22–26, setae Oe, L, He, Sce and Le L 16–19; setae Ci, Se, Pi, Pe 12–16; setae Ai and Ae 9–10; excretory pore plate L 9–14, W 7–12; urstigma L 6-8, W 9–11; basal segments of chelicerae L 62–73, cheliceral stylet L 15–16; pedipalpal segments (P-1–5) L: 5–6, 27–31, 20–24, 11–13, 10–12; leg segments L: I-Leg-1–6: 21–23, 15–19, 16–18, 22–26, 28–30, 53–57; II-Leg-1–6: 21–24, 16–18, 11–13, 15–18, 22–26, 43–46; III-Leg-1–6: 21–24, 15–16, 10–13, 17–19, 22–28, 40–44.

Female. Integument soft with short rounded papillae ( Fig. 27 ). Frontal plate ( Fig. 28 ) with a bluntly pointed medioanterior projection, prominent anterolateral extensions, lateral and posterior margins concave, posterior projections long; median eye small and situated nearly on the level of anterior pair of setae.

Capitulum ( Fig. 29 ) with equally S-shaped ventral margin and short rostrum (base of capitulum/rostrum L 5.0–6.7). Chelicera ( Fig. 30 ) rather slender, basal segment with obtuse-angled dorsal hump near middle, stylet moderate in length.

Pedipalp ( Fig. 31 ) robust: P-1 with one to three dorsodistal setae; P-2 with 8–12 setae; P-3 with three to four setae; P–4 rather slender with three thin distal unequal setae and a short, thick dorsodistal spine.

Measurements, n=5. Idiosoma L 1300–2040; dorsal plate L 475–500, W 430–450; genital flap L 250–275, W 110–120; genital acetabula (ac.1–ac.3) L 35–40, 30–37, 60–65; capitulum L 265–275, rostrum L 35–45, chelicera L 360–375, cheliceral stylet L 120–125; pedipalpal segments (P-1–5) L: 75–85, 130–140, 75–90, 170–180, 30–32; leg segments L: I-Leg-1–6: 85–100, 110–125, 150–165, 250–265, 250–275, 260–275; II-Leg-1–6: 85–100, 110–125, 185–200, 320–335, 360–375, 335–350; III-Leg-1–6: 100–110, 150–160, 200–215, 310–325, 355–375, 325–350; IV-Leg-1–6: 210–225, 200–215, 300–315, 435–450, 410–425, 335–350.

Remarks. The larva of the present species is similar to the larva of H. crassipalpis Koenike, 1914 . The latter species differs at the larval stage in: (1) ventral idiosomal setae Ci, Se, Pi, Pe and Ai being slightly longer and thicker than Ae; (2) P-2–3 short (16 µm and 15 µm, respectively);) and P-5 solenidion short, not longer than segment ( Wainstein 1980, Biesiadka & Cichocka 1990).

Figures

FIGURES 17 – 18. H. dispar (Schaub, 1888), larva: 17, dorsal view; 18, ventral view. Scale bar: 20 µm.

FIGURES 19 – 26. H. dispar (Schaub, 1888), larva: 19 – 20, excretory pore plate; 21, chelicera, dorsal view; 22, pedipalp, ventrolateral view; 23, I-Leg- 4 – 6; 24, II-Leg- 4 – 6; 25, III-Leg- 4 – 6; 26, claws of leg III. Simple setae on I – III-Leg- 4 – 6 are not shown. Scale bars: 21 = 50 µm, 19 - 20, 23 – 26 = 20 µm.

FIGURES 27 – 31. H. dispar (Schaub, 1888), female: 27, fragment of integument; 28, frontal plate; 29, capitulum; 30, chelicera; 31, pedipalp. Scale bars: 27 = 50 µm, 31 = 100 µm, 28 – 30 = 200 µm.