Copidognathus angusticeps, Bartsch, Ilse, 2007

Bartsch, Ilse, 2007, Halacarid mites (Acari: Halacaridae) from Esperance (Western Australia), description of two new Copidognathus species, Zootaxa 1435, pp. 41-49 : 42-45

Copidognathus angusticeps spec. nov.

Figs 1–12

Material examined. Holotype female, WAM T78346, Western Australia, Esperance, Duke of Orleans Bay, 33°55’S, 122°35’E, from seagrass ( Amphibolis spec.) with epiflora and fauna, 17 February 2003.

Diagnosis. Length 490 µm. Dorsal plates reticulate and densely punctate, with delicately raised areolae. PD with single pair of costae. Anterior pair of gland pores on PD in margin of plate level with insertion of leg IV. Epimeral pores large. Gnathosoma 0.36 of length of idiosoma. Rostrum extending to end of P-3, basal pair of maxillary setae in basal half of gnathosomal base. Legs slender. Telofemora with coarse porosity. Tibiae I to IV with 2, 2, 1, 1 bipectinate setae. Tarsi with 4, 4, 4, 3 dorsal setae. Pectines of paired claws with numerous delicate tines.

Description. Length 490 µm, width 277 µm. Surface of dorsal plates with delicate pits, 1–2 µm in diameter, which are arranged within polygons and at low magnification demonstrate a faint reticulation ( Fig. 1 ); deeper integumental layers with numerous canaliculi giving the plates an intense punctate ornamentation. Within slightly raised areolae reticulation more conspicuous and polygons smaller than in remainder of plate. Length of AD 157 µm, width 117 µm, with elongate pair of porose areolae, gland pores in lateral margin at the level of insertion of legs I. Length of OC 105 µm, width 80 µm. Lateral margin with two gland pores and a pore canaliculus ( Fig. 3 ); raised area slightly oblique. PD almost twice length of AD, its length 305 µm, width 179 µm; anterior margin ovate. With pair of slightly raised costae, about one or two polygons wide. One pair of gland pores in lateral margin, at 0.59 relative to length of PD or level with insertion of leg IV. Following pair of gland pores in posterior margin of plate. Dorsal setae short, slender. Pair of ds-1 on AD posterior to the level of gland pores; ds- 2 in anterior margin of OC; ds-3 to ds-5 on PD immediately lateral to costae.

Ventral plates almost evenly punctate and faintly reticulate. Length of AE 164 µm, width 245 µm, without epimeral processes ( Fig. 2 ). Pair of epimeral pores within slight cavity; pores enlarged, inner diameter about 6 µm, outer diameter 15 µm. Opening of pores concealed by wide tines and densely arranged filaments ( Fig. 4 ). AE with three pairs of setae. PE extending distinctly beyond insertion of leg IV; its length 244 µm. PE with four to five long setae, one dorsal seta and three to four ventral setae. Length of GA 260 µm, width 184 µm, with three and four pgs. Length of GO 104 µm, width 55 µm. Distance from anterior margin of GO to that of GA slightly more than length of GO. Ovipositor extending somewhat beyond GO.

Gnathosoma slender, 2.8 times longer than wide, its length 174 µm, width 63 µm. Lateral and ventral flank of gnathosomal base porose ( Fig. 5 ); dorsal flank with delicate pits. Tectum triangular ( Fig. 6 ). Rostrum almost as long as gnathosomal base. Apical pair of maxillary setae at about 0.41 relative to length rostrum, basal pair of setae in basal half of gnathosomal base or 0.23 relative to length of gnathosoma (from basis to tip of gnathosoma). Rostral sulcus extending to apical pair of setae. P-2 with dorsal seta at 0.78; P-4 with three setae in basal whorl; apically with two spurs and one setula.

Legs slender; without lamellae or fossa membranes. Lateral flanks of telofemora and tibiae I and II with coarse porosity; porosity of lateral flanks of trochanters, telofemora and tibiae III and IV present but somewhat more delicate. Medial flanks of telofemora reticulate, accordingly ventral and dorsal margin crenulate; each polygon punctate and enclosing pits. Length:height ratio of telofemora I to III 2.5–2.6:1 ( Figs 8–10 ); telofemur IV 2.8 times longer than high ( Fig. 11 ). Telofemora I and II longer than the legs’ tibiae, telofemora of legs III and IV shorter than their tibiae. Leg chaetotaxy: leg I, 1, 2, 5, 4, 7, 6–7; leg II, 1, 2, 5, 4, 7, 4; leg III, 1, 2, 2, 3, 5, 4; leg IV, 0, 2, 2, 3, 5, 3. Tibiae I to IV with 2, 2, 1, 1 bipectinate, bluntly ending ventromedial setae and 1, 1, 1, 1 slender, smooth ventral setae. Tarsus I with four dorsal setae, included the long, slender solenidion; ventrally on one tarsus three on the other tarsus two setae ( Fig. 8 ). Tarsus II with four long setae, solenidion seta-like, 43 µm long, in dorsolateral position ( Fig. 12 ). Dorsomedial fossary seta much shorter than conspicuously long lateral fossary seta. On tarsi I and II two distal fossary setae situated unpaired, on tarsi III and IV paired. Tarsi I and II each with pair of doubled pas; at tip of tarsus III medial pas slender, setalike, lateral pas short, bristle-like; at tip of tarsus IV both medial and lateral pas short, bristle-like. Claws slender, all with accessory process. Pectines of claws II to IV with numerous delicate tines. Ventral plates AE, PE and GA with suctorians, their length about 59 µm; theca annulated ( Fig. 13 ), 39 µm long, and stalk 19 µm.

Etymology. Because of its narrow gnathosoma the species is called angusticeps , derived from angustus (Latin), narrow, and ceps (Latin), head.

Remarks. A character, not found elsewhere in the genus Copidognathus , is the presence of two gland pores on the OC. In general Copidognathus species have four pairs of pores in all, one pair of pores is on the AD, one pair on the OC and two pairs are on the PD. The gland pores may be almost vestigial or very conspicuous, opening on raised cones. Five pairs, as present in many other genera, is expected to be the plesiomorphic state, and the presence of two gland pores on the OC is a common phenomenon in several halacarid genera, amongst others in Halacarellus Viets , Isobactrus Newell and Rhombognathus Trouessart. The pores are rarely adjacent, as in C. angusticeps and in Mictognathus secundus Bartsch, 1992 . Two gland pores on the OC of C. angusticeps may be an anomaly of this specimen or species, but might also represent a situation otherwise reduced in the genus Copidognathus or a duplication of the gland pore always present on the OC.

In Copidognathus angusticeps the PD bears the anterior pair of gland pores in the margin of the plate. A similar position is found in, e.g., C. amalus Bartsch, 1999 , C. brachystomus Viets, 1940 and C. biodomus Bartsch, 1997 , species recorded from southwestern Australia, Europe and eastern Canada, respectively ( Bartsch 1997, 1999, 2001; Viets, 1940). Copidognathus angusticeps and C. amalus are similar in their general shape but differ in the ornamentation of the dorsal plates, the shape of the OC and the size of the epimeral pores. The dorsal plates of C. angusticeps demonstrate a faint reticulation due to minute pits which are arranged in polygons, the width of the OC is less than 1.5 times the length and the epimeral pores are more than 10 µm in width, in contrast, the dorsal plates of C. amalus are characterized by the wide porose areolae with rosette pores ( Bartsch 1999: fig. 6A and C), the OC, with a tail-like posterior process, are three times longer than wide, and the epimeral pores are 3 µm in diameter. The dorsal plates of both C. biodomus and C. brachystomus bear areolae with rosette pores, the length of the gnathosoma is less than 1.5 times the width (versus 2.8 in C. angusticeps ), the epimeral pores 3–5 µm in diameter, and the length of telofemur I less than twice the height (versus a length:height ratio of about 2.5 in C. angusticeps ).

The epimeral pores of C. angusticeps are enlarged and obscured by tufts of filaments. Enlarged epimeral pores are known in C. dactyloporus Benfatti et al., 1989 , C. tectiporus ( Viets, 1935) , C. hephaestios Benfatti et al., 1992 , C. poriferus Bartsch, 1979 , and C. profundus Viets, 1936 , all living in low salinity habitats ( Viets 1935, 1936; Bartsch 1979; Benfatti et al. 1989, 1992), and in these species the enlargement of the pores is expected to facilitate the osmoregulation and thus be of competitive advantage in a life in freshwater.

Distribution. Esperance, Western Australia. The single individual recorded was extracted from the epibios on seagrass.

Figures

FIGURES 1 – 7. Copidognathus angusticeps spec. nov., male, 1, idiosoma, dorsal; 2, idiosoma, ventral; 3, ocular plate; 4, part of AE with epimeral pore; 5, gnathosoma, ventral; 6, gnathosoma, dorsal; 7, palp. (glp, gland pores; pa, porose areola; pc, pore canaliculus) Scale = 50 µm.

FIGURES 8 – 13. Copidognathus angusticeps spec. nov., male, 8, leg I, medial (seta in dotted line absent on this leg); 9, basifemur to tarsus II, medial; 10, leg III, medial; 11, leg IV, medial; 12, tarsus II, lateral (medial setae and claw in broken line). Scale = 50 µm. 13, Suctoria from Copidognathus angusticeps spec. nov.