Acarothrix umgenica, Proches, 2002

Prochesë, Së Erban, 2002, New species of Copidognathinae (Acari: Halacaridae) from southern Africa, Journal of Natural History 36 (8), pp. 999-1007 : 1005-1007

Acarothrix umgenica sp. nov.

(®gure 4)

Material. (BMNH(E) 2001±13) HOLOTYPE: male, South Africa, KwaZulu- Natal, Beachwood mangroves in Durban , 18 August 1999, leg. SË. ProchesË . PARATYPES: one male, same data as for holotype; two females, two protonymphs, and one larva, same locality as the holotype, 26 October 1999, leg. SË. ProchesË . Other material was collected in Richards Bay ( South Africa, KwaZulu-Natal). In all, around 30 specimens were examined, all of which were collected in sediment or algae covering the pneumatophores of the mangrove-tree Avicennia marina .

Adults. Sexes very much alike; no signi®cant diOEerence in body or plate sizes. Idiosoma 325±385 Mm long and 230±300 Mm wide.

Dorsum. All plates thin, apparently smooth, although high magni®cations reveal complex cuticular patterns. AD 80±90 Mm long and 100±105 Mm wide, with a posterior transversal strip-shaped part where a reticulation is visible. OC 105±130 Mm long and 85±105 Mm wide, with two corneae, one anterior seta and, locally, unclear reticulation. ds-3 could not be located. PD 220±230 Mm long and 105±115 Mm wide, with three pairs of setae: ds-4 and ds-5 placed centrally, equally distant from a pair of gland pores; ds-6 ventral, close to anal opening, next to a pair of small glandbearing cones, indistinct in some individuals. A central pattern of canalicular polygons is more visible in the anterior half of PD; in many individuals, particularly if well cleared, this plate appears to be completely smooth (®gure 4A).

Venter. All plates with ®ne, evenly arranged canaliculi. AE 150±155 Mm long and 210± 255 Mm wide, with three pairs of ventral setae and a pair of large pores. PE 170± 220 Mm long, with one dorsal and three ventral setae. GA 155±175 Mm long and 120± 160 Mm wide, with a fold between the genital part and the anal part (®gure 4B).

Male genitalia. Eight to 10 pairs of perigenital setae, sometimes asymmetrically disposed. Subgenital setae: two pairs setiform and two spur-like. Behind the last spur-like setae, a pair of genital acetabula can sometimes be observed (®gure 4H).

Female genitalia. Three pairs of perigenital setae surround the genital opening; and one pair of anterior subgenital setae (®gure 4I).

Gnathosoma . Gnathosoma 125±170 Mm long and 55±90 Mm wide, palpi longer than rostrum. Gnathosomal base with evenly arranged canaliculi. Distal palp segment with a whorl of three long basal setae and one short subterminal seta (®gure 4C).

Legs. First pair more robust, the other pair long and slender. Chaetotaxy of legs, from trochanter to tibia: leg I, 1, 2, 5, 4, 6; leg II, 1, 3, 5, 4, 6; leg III, 1, 2, 3, 3, 5; leg IV, 1, 1(?), 3, 3, 5. Claws very long, especially in legs II, III, IV, almost smooth, dent of accessory process indistinct (®gure 4D±G).

Juvenile stages. Plates very thin, with poorly de®ned limits. The integument is generally smooth.

Protonymph. Idiosoma 245±320 Mm long and 200±235 Mm wide.

Gnathosoma . Gnathosoma 120±155 Mm long and 80±85 Mm wide.

Legs. Basifemur and telofemur IV merged in one femoral segment.

Larva. Idiosoma 235±265 Mm long and 175±205 Mm wide.

Gnathosoma . Gnathosoma 110±120 Mm long and 40±60 Mm wide.

Legs. Femoral segments merged in all legs.

Etymology. The name umgenica refers to the river Umgeni (alternative spellings: Mgeni, mNgeni, uMngeni), from whose estuary the specimens were collected. According to Begg (1978), the name means in Zulu`the river that ¯ows among thorny trees ( Acacia )’.

Remarks. Acarothrix umgenica sp. nov. diOEers from the other two species of Acarothrix (compare Bartsch, 1990, 1997a) in the relative size of the dorsal plates: in the new species AD is much smaller and PD is larger. The shape of OC is also diOEerent, with longer posterior tips. The fold separating the anal and genital parts of AG, present in slide-mounted males and females, indicates a strong convexity of the genitalia, not noted in the other Acarothrix species. The reticulation present on PD is similar to that illustrated by Bartsch (1990) for A. palustris protonymphs, but in the new species this could only be observed in adults. No canalicular punctuation on the ventral plates has been described in either A. palustris Bartsch, 1990 or A. longiunguis Bartsch, 1997 .

This is the ®rst record of the genus Acarothrix from the African continent. Previously, the genus was known from southern China and northern Australia ( Bartsch, 1990, 1997a). This distribution is possibly congruent with that of Indo- West Paci®c mangrove forests.