Short Communication |
Corresponding author: Andrzej Zawal ( zawal@univ.szczecin.pl ) Academic editor: Vladimir Pesic
© 2019 Elham Arjomandi, Andrzej Zawal, Hamidreza Hajiqanbar, Ewa Filip, Magdalena Szenejko.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Arjomandi E, Zawal A, Hajiqanbar H, Filip E, Szenejko M (2019) New record of a parasitising species of Hydrachna (Acari, Hydrachnidia) on water beetles Eretes griseus (Fabricius, 1781) (Coleoptera, Dytiscidae, Dytiscinae, Eretini). ZooKeys 865: 31-38. https://doi.org/10.3897/zookeys.865.34532
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The larvae of water mites of the genus Hydrachna parasitise water bugs and water beetles. Larvae of the genus Hydrachna attach to the thorax and abdomen sternites and tergites under the elytra. Up to now six species of Hydrachna were recorded from Iran, but there are no records on larvae parasitising on water beetles. There is some information about parasitising of Hydrachna on water beetles from the genus Eretes, which is very well adapted to dry climate. The aim of this paper is to describe the morphology of an unknown larva of the genus Hydrachna, found on Eretes griseus.
Iran, larva, morphological features, taxonomic status, water beetles, water mites
Many organisms are dependent on a living host for some part of their life cycle or even the whole life. These symbiotic relationships categorised as mutualistic, commensal or parasitic, while specific specialisation occurs in commensalism and mutualistic symbionts, higher levels of co-evolution can be found in parasitic relationships. Among different groups of mites, larval stages of the cohort Parasitengonina parasitise a wide range of arthropods including terrestrial, freshwater or marine insects (
Beetles of the genus Eretes are specifically adapted to desert environments and a dry climate, where they can find small and isolated, warm, standing, water sources such as pools with clayey or sandy bottom and little vegetation (
The larvae were collected as parasites on Eretes griseus from a volcanic area on a mountainside, nearly 1,840 meters above the sea level, Badab-e Soort) 36.3549N, 53.8565E (in Mazandarn province, northern Iran (Fig.
All small larvae (0.15–0.40 mm) were detached from surfaces of the mesosternum of the beetle body (Fig.
Idiosomal setae are named according to
Cx-1-3 coxal plates,
Hu humeral seta,
L length,
Lp1, Lp2 lateropropodosomal setae,
Lh3 laterohysterosomal seta,
Mh1, Mh2, Mh3, Mh4 mediohysterosomal setae,
Mp1, Mp2 mediopropodosomal setae,
n number of specimens measured,
P–1–5 pedipalp segments (trochanter, femur, genu, tibia and tarsus),
I–Leg-1–5 first leg, segments 1–5 (trochanter, femur, genu, tibia and tarsus) i.e.,
III– Leg–3 genu of third leg,
W width.
All measurements are given in micrometres (μm).
The idiosoma are oval, with the integument striated, and the dorsal plate is very large, covering the whole idiosoma of unengorged larva, the integument pointed and with a concave anterior edge (Figs
In µm, n = 3. Dorsal plate: L/W 250–254/162–157; coxal plates: Cx-1 L 40–45, Cx-2 L 20–22, Cx-3 42–44; excretory pore plate L/W 17–18/16–17; gnathosoma; L/W 173–176/138–140; diameter of sucker ring 71–73; pedipalpal segments (P-1–3) L: 8–9, 36–38, 39–42; leg segments L: I-leg 1–5: 18–19, 37–39, 32–34, 38–40, 67–69; II-leg 1-5: 20–21, 32–34, 29–30, 37–39, 68–70; III-leg 1-5: 28–29, 29–30, 27–28, 38–40, 61–64.
The larva of Hydrachna sp. is most similar to larvae of H. processifera described by
At the current level of research, we propose to leave the taxonomy of the genus Hydrachna without sub-division, indicating the existence of greater morphological differentiation. Relationships within the genus of Hydrachna should be recognised on the basis of molecular studies and a decision on the possible splitting the genus into subgenera should be made. Up to now six species of Hydrachna were recorded from Iran (H. cruenta, H. skorikowi, H. sepasgozariani, H. cf. vaillanti, H. sistanica, H. globosa lacerata), and two of them (H. sepasgozariani, H. cf. vaillanti) belong to the Hydrachna processifera group of species (