Pelopsis HALL, 1919

Behan-Pelletier, V., Eamer, B. & K. W, 2003, Redefinition Of Pelopsis (Acari: Oribatida: Mycobatidae), With Description Of Pelopsis Baloghi Sp. N. From Costa Rica, Acta Zoologica Academiae Scientiarum Hungaricae 49 (1), pp. 5-15 : 6-10

Pelopsis HALL, 1919

Type species: Pelops bifurcatus EWING, 1909 (= Pelopsis nudiuscula HALL, 1911 )

Diagnosis. Adults areuniqueamong theMycobatidaein having thefollow - ing combination of character states: granular cerotegument extending ventrally in groove at edge of ventral plate; rostrum with lateral minitecta; enantiophysis pres- ent between base of seta in and bothridium; seta in borne on ridge extending between enantiophysis; seta in broad, heavily barbed dorsally and laterally, bifurcate distally; tutorium with large triangular cusp; pedotectum I with proximal third concave, expressed as narrow ridge, strongly convex medially; semicircular carina present close to margin of ventral plate, between circumpedal carina and porose area Ah; circumpedal carina not merging with discidium; octotaxic system of four pairs of saccules; posterior notogastral tectum without overlapping lobes; subcapitulum without mental tectum.

Description. Poronotic, brachypyline oribatid mites, with character states of the Mycobatidae ( GRANDJEAN 1954) . Adult: Granular cerotegument restricted to region between pteromorphs, pedotectum I, tutorium, and lateral body wall, extending medially along dorsosejugal scissure and circumventrally in groove at edge of ventral plate ( Fig. 14). Rostrum convex, margin medially concave, with or without lateral dens. Rostrum with pair of lateral minitecta extending from ventral of lamellar setae to edge of genal process ( Fig. 12). Rostral seta barbed, directed anteromedially. Lamella present or reduced to ridge, with or without cusp; translamella absent. Lamellar setae borne anteriorly or anteroventrally on cusp, or borne directly on prodorsum. Interlamellar seta broad, strongly barbed dorsally and laterally, bifurcatedistally ( Figs 7, 9), borneon ridge( Fig. 9). Enantiophysis welldeveloped between base of seta in and bothridium ( Fig. 9). Bothridium cup-shaped ( Fig. 9). Sensillus clavate ( Figs 1, 8, 9). Porose area Ad present. Tutorium with well-developed triangular cusp. Pedotectum I with proximal third concave, expressed as narrow ridge, strongly convex medially; not covering base of exobothridial seta ( Fig. 3). Porose areas Am and Ah present, porose area Al absent. Discidium large, triangular ( Fig. 2). Posteriorly directed, semicircular carina present posterodorsal of acetabulum IV, between circumpedal carina and porose area Ah ( Fig. 3; arrowhead). Postanal porose area present or absent. Dorsal apodemes (dorsophragmata) separate. Notogaster with 10 pairs of setae or their alveoli. Notogaster with medial process on anterior tectum, process flattened or slightly convex, often covering base of seta in ( Fig. 8). Pair of thickened bands of integument bordering medial process, evident in transmitted light. Concave ridges extending from medial process almost to anterior edge of pteromorph ( Figs 9, 10). Lenticulus present. Octotaxic system present as four pairs of saccules. Pteromorphs curved ventrally, with line of desclerotization clearly evident, extending four-fifths length of pteromorph ( Fig. 7). Undivided posterior notogastral tectum present. Epimeral setal formula 3–1–3–3. Small custodium present. Circumpedal carina ending on ventral plate medial to discidium ( Fig. 13). Spermapositor (male genital sclerite) normal for family, approximately half length of genital plate, when measured in ventral view on slide-mounted specimens. Genital papilla Va of maleand femalesubequal in sizeand shapeto Vm and Vp. Palp setal formula 0–2–1–3–9(1).

Subcapitulum without mental tectum. Gena without posteriorly directed tectum covering base of seta m. Seta l’ of palptibia setiform. Axillary saccule of subcapitulum present. Tarsi tridactylous. Dorsal integument of tibiae and tarsi II and IV thickened ( Fig. 5). Femora II to IV with projection ventrally and abaxially. Seta s of tarsus I eupathidial; seta l” on genua I and II setiform ( Fig. 14). Tarsus II with or without dens abaxial to solenidia.

Immatures – Unknown.

Relationship. We have examined the syntypes of Pelopsis bidentatus ( HAM- MER 1961 ). The purported longitudinal groove and the “sense papillae” on the rostrum noted by HAMMER (1961) arethickenings of thebaseof therostral tectum .

These, present in all species of Pelopsis , are visible in transmitted light, but being enclosed in the camerostome, are not evident in scanning electron micrographs ( Figs 10, 12). The lamellae are lamellate proximally and ridge-like distally. The “short ridges” on the anterior of the notogaster are the thickenings of the notogastral tectum present in all species of Pelopsis .

trochanter removed. Scale bar represents 50 µm

In Pelopsis the cerotegument extends as a circumventral band in the groove formed at the edge of the ventral plate. A similar development of the cerotegument is found in all members of the ceratozetoid family Zetomimidae ( BEHAN- PELLE- TIER & EAMER 2003). It is possiblethat in Pelopsis this band of cerotegument forms a “circumventral plastron” as has been observed in the zetomimid genus Heterozetes ( BEHAN- PELLETIER & EAMER 2003).

The presence of a semicircular carina posterodorsal of acetabulum IV and close to the margin of the ventral plate, is a character state shared with the mycobatid genera Mycobates and Punctoribates . These latter genera also have a linear carina, anterior to the semicircular carina, which is also found in the mycobatid genus Zachvatkinibates ( BEHAN- PELLETIER 1994). The pedotectum I with strongly concave dorsal margin is a character state also found in the genera Punctoribates and Minunthozetes and in some species of Zachvatkinibates ( BEHAN- PELLETIER 1988).

The presence of (1) minitecta on the rostrum; (2) bifurcate and barbed interlamellar setae, and (3) octotaxic system developed as saccules, are character states uniqueto Pelopsis among theMycobatidae(B EHAN- PELLETIER 1988). Pelopsis shares the following four character states with the mycobatid genera Zachvatkinibates , Punctoribates and Minunthozetes : interlamellar setae borne on a ridge; enantiophysis present between interlamellar setae and bothridium; notogaster with medial process; thickened bands bordering medial process. These character states are considered synapomorphic ( BEHAN- PELLETIER 1988), and definethesubfamily Minunthozetinae GRANDJEAN (sensu SHALDYBINA (1975) and PAVLIT- SHENKO (1994)) of the family Mycobatidae .