Arrenurus stagnalis, Smit, 2020

Smit, Harry, 2020, New records of the water mite genus Arrenurus Dugès, 1834 from South America (Acari: Hydrachnidia: Arrenuridae), with the description of five new species and one new subspecies, Acarologia 60 (2), pp. 371-389 : 382

Arrenurus stagnalis n. sp.

Zoobank: 9621332F-ED4F-4069-9DE2-3362C251D86B

( Figure 8 )

Material examined — Holotype male, roadside pond along Afobakaweg , Surinam, 5°36.266 N 55°05.988 W, alt. 13 m asl, 19-xi-2019 ( RMNH) . Paratypes: one male, three females, same data as holotype ( RMNH) ; one male, ditch along Weg naar de Peperpot, 5°46.857 N 55°08.327 W, alt. 3 m asl, 18-xi-2019 ( RMNH) .

Diagnosis — Dorsal shield relatively wide, cauda relatively long with a medial pointed hump, posterior margin of cauda with a shallow indentation; palp without a patch of setae.

Description — Male: Idiosoma yellowish, dorsally 778 (810-842) long and 445 (462-470) wide, ventrally 818 (850-858) long. Dorsal shield incomplete, 328 (332-348) wide, 150 (162-170) distanced from anterior idiosoma margin. Cauda relatively long and slender with a pointed hump, posterior margin of cauda with a shallow indentation; in dorsal view two pairs of glandularia visible in posterior part of cauda. Anterior pair of coxae anterolaterally pointed. Gonopore 34 long, genital field 235 wide, not extending to lateral idiosoma margin. Length of P1-5: 22, 43, 34, 59, 36. P5 slender, P4 expanding anteroventrally, P2 medially with one long and two short setae (P2 is a bit rotated in Figure 7D ). Length of I-leg-4-6: 84, 82, 116. Length of IV-leg-4-6: 146, 94, 86; IV-leg-4 without a spur.

Female: Idiosoma dorsally 656 (640-648) long and 551 (531-543) wide, ventrally 656 (672-688) long. Dorsal shield complete, 510 long and 405 wide. Medial margin of Cx-IV longer than medial margin of Cx-III. Medial distance of Cx-IV slightly smaller than width of one genital valve. Gonopore 106 long, genital field 373 wide. Genital plates longer than broad. Length of P1-5: 23, 55, 40, 62, 33; palp as in male. Length of I-leg-4-6: 96, 90, 100. Length of IV-leg-4-6: 126, 116, 112.

Etymology — Named for its occurrence in pools.

Remarks — The male of the new species is most similar to Arrenurus ludificator Koenike, 1905 from Paraguay, A. thomseni K. Viets, 1993 from Uruguay, A. clavipes Lundblad, 1941 and A. undulatus Lundblad, 1937 , both from Brazil. From A. thomseni the new species differs in a wider and shorter dorsal shield and a more pointed hump on the cauda. Arrenurus ludificator and A. clavipes have a more slender dorsal shield, the cauda of A. ludificator is slightly widening posteriorly (not in the new species) with a smaller posterior indentation. Arrenurus undulatus has a straight posterior margin of the cauda and Lgl-4 is visible in dorsal view (not visible in the new species). The paratype males are much larger, but morphologically similar, and are, therefore, assigned to the new species.

Figures

Figure 7 Arrenurus niger n. sp. A-E holotype male, F paratype female. A – dorsum; B – venter; C – right palp; D – left palp (segments rotated); E – IV-leg-6; F = venter. Scale bars: A-B, F = 100 µm, C-E = 50 µm.

Figure 8 Arrenurus stagnalis n. sp., A-D holotype male, E paratype female. A – dorsum; B – venter; C – lateral view (not all details shown); D – palp; E – venter. Scale bars: A-C = 100 µm, D = 50 µm, E = 200 µm.