Arrenurus (Micruracarus) madaraszi Daday, 1898

Zawal, Andrzej, Bańkowska, Aleksandra, Krakowiak, Maja, Krzynówek, Zuzanna, Pešić, Vladimir & Michoński, Grzegorz, 2023, Description of Arrenurus (Micruracarus) madaraszi Daday, 1898 larva with some remarks on subgenera taxonomy, Zootaxa 5318 (1), pp. 145-147 : 145-147

Arrenurus (Micruracarus) madaraszi Daday, 1898

Material examined. In total 24 larvae were reared from two females (7 and 17 respectively). The duration of the embryonic period was 17 days. Ten larvae (five from each female) were measured.

Diagnosis. Dorsal plate oval and broad (L/W ratio 1.1-1.2) with slightly convex anterior margin. The anterior-lateral incisions fairly small with obtuse angles. CpII much shorter than CpIII (CpI/CpII/CpIII ratio 2.1/1.0/1.5). Exp situated posterior to the centre of Expp and beneath the E2 setae. Two setae on PV pectinate, IIITa14 small and situated anterior to IIITa13, lack IIITa8.

Description. Colour red. The dorsal plate oval and broad (L/W ratio 1.1-1.2) with slightly convex anterior margin and fairly small anterior-lateral incisions with obtuse angles; lateral margins slightly convex; posterior margin rounded.

Distances Mp1-Mp1 and Lp1-Lp1 shorter than Mp2-Mp2. Ratios: DpW/Mp1-Mp1 3.5–3.7; Lp2-Lp2/Mp1-Mp1 1.3– 1.5; Mp2-Mp2/Mp1-Mp1 1.1–1.2; Mh1-Mp2/Mp1-Mp1 0.96–0.97. The median margins of CpI is the longest followed by CpIII and median margins of CpII is the shortest (CpI/CpII/CpIII ratio 2.1/1.0/1.5). All the setae on the coxal plates bipectinate and rather thick ( Fig. 1 ). Distance between C1-CpI median margin reaches about 2/3 distance between C4- CpIII median margin. The C1-C2 distance long. The shape of the Expp rhomboidal with rounded anterior margin, and slightly pointed posterior margin, its width slightly larger than length. The Exp lies posterior to the centre of Expp and beneath the E2 setae. Pedipalps typical. The PIII1 fairly thick and pectinate, PV8 and PV7 pectinate, PV6 short. The first segment of the chelicerae elongated, curved and narrowing in the posterior part, with margins parallel to each other.

The segments of every leg have more or less the same proportions. The clearly shortest trochanter constitutes about 2/3 of the femur and genu which are of the same length; the tibia is slightly longer and the tarsus 1.5 times longer. The ITi8 seta is smooth and fairly thin and short, the IIGe3, IIIGe3 and IIIGe4 setae are fairly thin and smooth, IIITa13 long and pectinate, IIITa14 small and situated anterior to IIITa13, IIITa8 missing.

Measurements. n = 10. Idiosoma L 170–202, W 143–176; dorsal plate L 159–197, W 140–176; medial margin L: CpI 45–58, CpII 21–28, CpIII 32–39; distance: Mp1-Mp1 39–50, Lp1-Lp1 43–54, Lp2-Lp2 50–74, Mp2-Mp2 45–55, Mh1-Mp2 38–48, Mp1-Lp1 5–8, Mp1-Lp2 35–39, Mp1-Mp2 50–62, Mp2-Mh1 39–45, C1-C2 34–42, C1-CpI medial margin 14–17, 41-CpIII medial margin 20–24, Exp-Expp posterior margin 5–8, E1-Expp anterior margin 5–9; E2- Expp posterior margin 6–11; chela L 62–68; pedipalp segments (PI–PIII) L: 6–7, 16–22, 24–35; PIV claw L 14–17; PV8 seta L 105–126; leg segments L: I-Leg-1–6: 16–20, 21–25, 22–28, 30–40, 44–55; II-Leg-1–6: 20–25, 28–32, 28–31, 32–43, 51–62; III-Leg-1–6: 24–32, 25–32, 36–42, 53–62.

Remarks. The larva of the present species is similar to the larva of A. fimbriatus Koenike, 1885 ( Zawal 2006, 2008). However, the following clear differences can be found in their morphology: Expp is romboidal not oval like in A. fimbriatus Exp is situated further from the Expp centre and E2 setae, ratios between CpI/CpII/CpIII are different (2.1/1.0/1.5) than in A. fimbriatus (2.4/1.0/1.5), all setae on Cp in A. madaraszi are pectinate than in A. fimbriatus C1 setae are smooth, and the ratios between distances on dorsal setae in A. madaraszi (Lp2-Lp2/Mp1-Mp1 <1.6; Mh1-Mp2/Mp1- Mp1 <1.0) and A. fimbriatus are different (Lp2-Lp2/Mp1-Mp1> 2.0; Mh1-Mp2/Mp1-Mp1> 1.5).

Arrenurus madaraszi belongs to the subgenus Micrarrenurus established by Cassagne-Méjan (1966) but this subgenus is synonymized with Arrenurus s.s. by Gerecke et al. (2016). Morphological features of the larva of A. madaraszi mostly agree with the characteristics of the subgenus given by Zawal (2008), but there are some differences: Lp2-Lp2/Mp1-Mp1 <1.6; Mh1-Mp2/Mp1-Mp1 <1.0. Subgenera taxonomy in Arrenurus was questioned by Cook (1974), who suggested abandoning it and dividing the genus into groups of species only. Recent molecular studies support this opinion, as only the subgenus Arrenurus s. str. proved to be monophyletic ( Więcek et al. 2023). The resolution of this problem requires further studies based on molecular data using more molecular markers especially for nuclear locii or complete mitochondrial genome.

Figures

FIGURE 1. Arrenurus madaraszi larva. A—ventral side; B—dorsal plate; C—photograph of dorsal side; D—photograph of ventral side; E—chelicera; F—pedipalp. Scale bars = 50 μm.