Crotonia wallworki, Colloff, Matthew J., 2009

Colloff, Matthew J., 2009, Species-group concepts and biogeography of the genus Crotonia (Acari: Oribatida: Crotoniidae), with new species from South and Central America, Zootaxa 2081, pp. 1-30 : 13-16

Crotonia wallworki sp. nov.

(Figs. 7, 8)

Dimensions: holotype female length 1470, breadth 605; length and breadth of paratype females: no. 1: 1485, 640; no. 2 1500, 717; no. 3 1488, 678; length and breadth of paratype males no. 4 1344, 675; no. 5 1282, 641. Mean ratio of length of prodorsum to total length: females 0.3; males 0.32.

Female. Prodorsum: rostrum very prominent, 55 long, 74 broad; rostral setae 50 long, straight or very slightly curved, smooth. Lamellar setae recurved, ca. 305, with sparse barbed ornamentation (Fig. 7a). Lamellar apophyses extending anteriorly as far as apices of rostral setae; length 102: half their mutual distance. Interlamellar apophyses twice as long as broad; interlamellar setae stout proximally, flagelliform distally, smooth; extending anteriorly beyond apices of rostral setae but not as far as apex of arch of lamellar setae. Shallow curved prodorsal ridges extending about half the distance between interlamellar and lamellar apophyses; irregular, somewhat jagged posterior interbothridial ridge with small medial alveolar field present. Alveolar fields present posteriolateral of interbothridial ridge. Sensillus globular, enclosed in bothridium, with veined microsculptural covering. Prodorsal microsculpture porose, with sparse alveolar field present posteriolateral of interbothridial ridge.

Notogaster: ratio of length to breadth 1.7; broadest at seta e 2 (Fig. 7a). Dorsosejugal suture complex, with well-defined lateral margins but diffuse medial region and waisted, concave lateral regions bearing tubercles of setae c 3. Notogastral shield discrete, smooth, with diffuse porose microsculpture; bordered laterally by two thin strips of small tubercles becoming diffuse caudally and immediately posterior of setae of c series. Anterior margin of notogastral shield a transverse line just posterior of setae c 1. With 13 pairs of notogastral setae; all smooth. Setae of c series setiform (Fig. 8b); tubercles of c 1 and c 3 squat, no longer than broad, c 1 positioned on hyaline lenses of cuticle just anterior to margin of pre-notogastral shield; c 3 positioned anteriorly of c 1, on humeral margin just posterior of dorsosejugal suture. Distance between tubercles c 3 and c 1 and both c 1 140 and 180 respectively. Lateral hyaline strips present bearing tubercles of setae cp, e 2 and f 2; these setae subequal in length. Setae d 2 25, setiform, on alveoli. Tubercles of setae f 2 not prominent or extending beyond margin of notogaster. With gla positioned closely anteriolateral of f 2. Setae f 1 and h 1 subequal, ca. 80, on apophyses about 25 long, directed posteriolaterally, separate: ca. 50 apart; setae h 2 ca. 115, their apophyses about 3 times longer than those of f 1 and h 1, directed posteriorly, parallel, 190 apart; caudal margin between them a broad, oblique inverted V (Fig. 8d), though more transverse in paratype no. 2. Apophyses of setae h 3 18, positioned ventrally, anteriomedial of those of h 1. Caudal microsculpture with small, scattered foveolae, otherwise smooth.

Ven t er: epimeral microsculpture porose (Fig. 8a); epimeral setae smooth, spiniform, minute, formula 3-1- 3-3; seta 3c situated on large tubercle on anterior margin of epimere. Ventral margin of notogaster surrounding anal plates sharply V-shaped; genital plates sub-circular; posteriolateral margin of genital plates concave; posterior margin straight, transverse. Each genital plate 262 long, 130 broad with 8 spiniform setae about same length and shape as epimeral setae. Aggenital setae subequal to epimeral setae. Anal plate 53 broad, 355 long; adanal setae ad 1 slightly longer than others; p 1 curved, longer than others in p series, on well-developed tubercles closely adjacent (Fig. 8c).

Male. The description and figure of the dorsum of the male are based primarily on paratype no. 4.

Prodorsum: rostrum 38 long, 68 broad; rostral setae 35 long, straight or slightly curved, smooth (Fig. 7b). Lamellar setae recurved, ca. 220, barbed covered with columnar cerotegument. Lamellar apophyses extending anteriorly as far as rostrum; length 90: half their mutual distance. Alveolar fields present posteriolateral of interbothridial ridge. Rest of prodorsum as for female.

Notogaster: ratio of length to breadth 1.4; broadest between seta e 2 and f 2. Dorsosejugal suture complex, with diffuse medial region and waisted, setae of c series on well-defined pre-notogastral shield (Fig. 7b). Relatively broad (ca. 40) transverse strip of hyaline cuticle posterior of setae of c series. Notogastral shield as in female, but relatively broad; broadest in region just posterior of setae e 2 and with centrodorsal porose microsculpture separated from lateral strips of small tubercles by narrow (ca. 30-35) zone of smooth cuticle. Setae f 2 on prominent apophyses, extending beyond lateral margin of notogaster; caudal margin between apophyses of setae h 2 a broad, oblique inverted V. Setae h 2 straight, spiniform.

FIGURE 7. Crotonia wallworki sp. nov. a) holotype female, dorsal; b) paratype male, dorsal; c) p 1 cluster; d) setae of the c series e) caudal apophyses

Material examined and locality data. Type material: holotype female and one paratype female (no. 1) (both in ethanol), two paratype females (permanent mounts on custom-made cavity microscope slide, one mounted dorsally [no. 2], one ventrally [no. 3]) and two paratype males (on slide, as above, one mounted dorsally [no. 4], one ventrolaterally [no. 5]) ex. litter from Valdivian temperate rainforest, 580 m, Bosque de Fray Jorge National Park, Limar Province, Chile, coll. N. Platnick and O. Franke, 5th January 1985 ex. R. A. Norton collection (RAN 86-18). Types in ethanol deposited in Canadian National Collection of Insects, Arachnids and Nematodes, Ottawa, Ontario; types on microscope slides in collection of R.A. Norton, College of Environmental Science and Forestry, State University of New York, Syracuse.

Etymology. This species is named in memory of the late Professor Tony Wallwork (ex. School of Biological Sciences, Queen Mary College, University of London), in recognition of his contribution to research on the systematics, biogeography and ecology of oribatid mites, and for encouraging my early interest in acarology.

FIGURE 8. Crotonia wallworki sp. nov. holotype female: a) ventral; b) setae of the c series; c) p 1 cluster; d) caudal apophyses, dorsal.

Remarks. Crotonia wallworki has no obvious autapomorphies and at first sight appears relatively nondescript, except for its large size. But it can be differentiated from other species of the genus by the following combination of characters: 1) setae c 3 on squat tubercles, not prominent apophyses; 2) dorsosejugal suture incomplete, diffuse, complex; 3) setae f 2 setiform, on squat tubercles; not spiniform or on long apophyses protruding beyond margin of notogastral shield; 3) notogastral plate relatively long, narrow; with tuberculate microsculpture in caudal region; 4) epimeral and perigenital microsculpture porose; 5) setae p 1 strongly curved, longer than the other p setae, with their bases immediately adjacent.

This species has characteristics of the Cophinaria species-group and is similar to C. chiloensis in the arrangement of the caudal apophyses, the relative lengths of the marginal notogastral setae, the overall shape of the notogastral shield and its tuberculate lateral regions, as well as the barbed ornamentation of the lamellar setae. It differs in being almost twice as long and twice as broad; having a prominent rostrum with straight, anteriorly projecting setae, as opposed to a truncate rostrum with curved, ventrally-directed setae; and with epimeral seta 3c on a well-developed tubercle on the anterior margin of the epimere.

The evidence for associating the females and males of this species is based on the following characters: 1) the irregular, jagged border of the interbothridial ridge; 2) the alvelolar fields posteriolateral of the interbothridal ridge; 3) the porose notogastral plate with tuberculate microsculpture on the anterior, lateral and caudal regions; 4) the separated apophyses of setae f 1 and h 1; 4) the shape of the caudal margin between apophyses of setae h 2; 5) the relative dimensions of the notogastral setae; 6) the morphology of the dorsosejugal suture with a broad transverse hyaline strip of cuticle separating the pre-notogastral and notogastral plates. The main differences between the sexes are the smaller size of the male, the broader notogastral shield relative to its length, the more prominent apophyses of setae f 2 and the spiniform shape of setae h 2 compared with the female.