Parosus Sharp, 1887

Makranczy, György, 2014, Review of the genus Parosus Sharp, 1887 (Coleoptera: Staphylinidae, Oxytelinae), Revue suisse de Zoologie 121 (1), pp. 77-133 : 83-88

Parosus Sharp, 1887

Parosus Sharp, 1887: 704 ; type species: Parosus hilaris Sharp, 1887 (by monotypy).

DIAGNOSIS: Parosus can be recognized by the medially broadly and deeply incised labrum and unusually strong umbilicate cephalic and pronotal punctation. Members of the genus can be distinguished from the most closely related genera by a three-segmented tarsus, unmodified sternite VIII in both sexes, reverse trapezoid pronotum without marginal bead and in most species (except only 4 of the named) a medially deeply serrate fringe on the posterior margin of tergite VII, a comb-like formation with several large incisions (Figs 27-31).

DESCRIPTION: Medium-sized (2. 0-5.3 mm). Body strongly depressed, moderately densely pubescent. Specimens usually either 'bicoloured' or 'unicoloured' (these colouration types are referred to in the descriptions). When abdomen light coloured, hind margin (keel) of tergal fold on tergites III-VI-(VII) with a darker line. Head usually larger than pronotum, latter much broader apically than basally. Umbilicate punctation most prominent on head and pronotum, but punctation almost always strong on elytra as well. Abdominal segments mostly shiny with indistinct punctation.

Head. Clypeus in most cases recognizable as a shiny, almost unpunctured area, poorly delimited by obsolete epistomal groove (feeble, broad, arcuate depression). Dorsum of head with strong umbilicate punctation (Fig. 4). Supraantennal prominence generally well developed and a ridge (hypostomal suture?) leads to the upper edge of the eyes, in some species even running further posteriorly above the side of the head (temples, gena). Distance of supraantennal prominence and eye variable, sometimes very small, in other cases rather long. Spherical calotte of eye (Fig. 3) not fully occupied by facets, its hind part, a broader or thinner slice without facets, sclerotized, often continuing in a triangular projection posteriorly (hereafter referred to as postocular process). (This feature makes giving traditional measurements for the specimens somewhat difficult.) Gular sutures confluent anteriorly, sutures gradually divergent posteriorly from middle; near base sutures strongly divergent. Dorsum of head usually with a shallow medial/longitudinal impression connecting epistomal and occipital impressions. Punctation generally more sparse towards middle of vertex, lateral areas (especially near eyes) microsculptured interfering with punctation. Base of head slightly to strongly constricted to form well-defined/broad neck, but without distinct occipital groove (obsolete; evident as broad, arcuate depression). Antenna (Fig. 1) slightly incrassate apically, length of segment 1 almost equal to length of articles 2-3 together, basal dish (Fig. 2) from antennomere 4 onwards quite prominent, sculpture from article 5 onwards strong. Compound eyes vary in size and appearance: from rather small (less than 1/4 length of temples) to rather large (length almost equal to length of temples); often they bulge, but in some species fitting into the arch of temples. Median portion of labrum bearing a U-shaped deep emargination with strongly sclerotized border and two small teeth on anterior margin, emargination often broadly rounded at base (Fig. 18) but sometimes only narrowly rounded (Fig. 97). Lateral portions bearing large membranous lobes. Anterior lateral edge (laterad of emargination) less sclerotized, rather truncate. Mandibles (Figs 9-10) denticulate with four teeth, first three following each other at equal distances, fourth separated by rounded emargination and itself rather round. Prostheca extending from inner edge, about half as long as mandible itself, composed of rather long and weak processes. In maxilla, cardo very small, transversally elongate triangular, lacinia enlarged with basal lobe, galea relatively smaller, both with moderately dense setation on apex. Maxillary palpus (Fig. 7) with first segment very small and ringlike, second and third segments rather large, with apex broadening and about equal in size and shape, fourth segment (Fig. 8) slender and acicular, length about half of second or third segment. In labium (Fig. 11), mentum (Fig. 17) trapezoid. Hypopharynx (Fig. 12) laterally with row of bulbous setae, some at midline also. One lobe with spinelike setae. Coronal pegs (sensillum basiconicum) (Fig. 13) scattered on disc of hypopharynx and a few at middle near apical edge. Labial palps (Fig. 15) three segmented, each segment about the same in length, but with width only about 3/4 the width of the previous segment. Third segment with a couple of very short sensillae on tip. Second segment with one coronal peg at apex, first segment with a few also at its apex. Platelike armature in hypopharynx as in Fig. 16.

Thorax. Prosternal process pointed, scutellum without pubescence, hypomera not exposing protrochantins. Pronotum with reverse trapezoid shape, sides strongly convergent from middle to base, posterior edge margined. Posterior part of pronotal midline usually appearing as elevated shiny stripe. Disc with umbilicate punctation. – Legs. Tibia (Fig. 5) with mid-tibial spur(s) and spines or rows of stiff setae. Tarsal segmentation 3-3-3 (Fig. 6) with no pseudosegment. Ventral setae modified to form tarsal lobes, last tarsomere only with sparse setae. – Elytra. Elytra without distinct puncture-rows, elytral suture parallel, epipleural ridge present.

Abdomen. Abdomen with two pairs of laterosclerites. Intersegmental membrane without brickwall pattern. Second sternite fully developed, first sternite completely absent. Tergal basolateral ridges absent, carina not present on any sternites. Fimbriate edge on tergite VII either modified medially (see under species treatments) or unmodified (in a minority of the known taxa). Sternites VII-VIII lacking peculiar modifications in both sexes. Tergite X (Fig. 21) with oblique desclerotized lines (suggesting precursor state to "rhomboid fusion" but basolateral parts still not fused to tergite IX), dorsal struts not developed, formation the same in both sexes.

Secondary sexual characters. With a slight expression of macrocephaly (mostly a great variability among individuals, rather than a real difference between sexes). – Male terminalia. Sternite IX (Fig. 20) present, with setae on apex. Tergite IX (Fig. 19) with small, slender ventral strut. – Male genitalia. Aedeagus median lobe bulb-like, internal sclerites present but weakly sclerotized, inconspicuous, symmetrical/paired. Apical opening simplified, truncate. Median face membranous, without apicomedial hook. Parameres not wrapping, without extra lobe or membranous region, with only one strong bristle on each. Without visible pump and flagellum. – Female terminalia. Tergite IX (Fig. 32) with only a trace of a ventral strut. Female genital appendages (Fig. 33) divided into coxites, valvifers but no styli. – Female genitalia. Spermatheca (Figs 34-36) sclerotized. Receptacle divided, not associated with visible spermathecal gland, tubular portion not penetrating distal bulb, umbilicus absent.

FIGS 1-6

Parosus gigantulus sp. n.; left antenna (1), antennomeres 4-6 (2), left eye (3), punctures on dorsal head surface (4), metaleg (5), metatarsus (6). Scale bar = 0.03 mm for 4, 0.12 mm for 3, 0.15 mm for 2, 0.17 mm for 6, 0.3 mm for 1, 0.4 mm for 5.

DIVERSITY: The genus has previously stood with 3 described species. Based on the examined material it looks likely that the real diversity could be at least double of the number of species treated here (i.e. upwards of 40 species). Considering the rapid destruction of the Neotropical forests and the primary wooded habitats in general, it is possible that many species go extinct without ever being discovered.

DISTRIBUTION: Parosus is a montane Neotropical genus: in Central America it occurs south of Nicaragua, in the West Indies south of Puerto Rico, in South America only present in the tropical areas. Southernmost occurences: Peru, Bolivia, Brazil (Estado de São Paulo).

NATURAL HISTORY: Not much is known about the bionomics of most species, collecting methods for half of the species are unrecorded. Many of the specimens are captured in flight intercept traps or window traps, some collected in litter or by beating branches. The information gathered so far suggests that at least some species actually live in foliage.

Parosus antillarum Wendeler, 1928 Figs 40, 52-55 Parosus antillarum Wendeler, 1928: 33. – Blackwelder, 1943: 104. – Herman, 1970: 400. Parosus antillarus: Herman, 2001: 1463.

TYPE MATERIAL EXAMINED: HOLOTYPE (♀), “Trois Rivières; ( Guadeloupe); Dufau \ Parosus ; antillarum; Fvl. \ Parosus ; antillarum n.sp.; Wendeler det. \ Holotypus \ antillarum x; Wdlr. \ Holotypus; Parosus ; antillarum Wendeler; ver. Makranczy, 2000 \ Parosus ; antillarum Wendeler; det. Makranczy, 2000” ( ZMHB).

OTHER MATERIAL: FRENCH ANTILLES: Guadeloupe [15°58'N, 61°38'W], leg. Plason (coll. Bernhauer, FMNH, 1). – TOBAGO: 10km NE Roxborough, Gilpin Trail , montane rain forest [11°18'N, 60°33'W], 400-500m, 26-31.VI.1993, leg. S. & J. Peck (#93-50), flight intercept trap ( FMNH, 13) . – VENEZUELA: Aragua, Rancho Grande Biol. Stn., 1140m, 10°21'N, 67°41'W, 1-8.III.1995, leg. Robert W. Brooks (#045), flight intercept trap ( SEMC, 13), Aragua, Rancho Grande Biol. Stn., Pico Periquitos, 1300m, 10°21'N, 67°41'W, 27.II.-6.III.1995, leg. Robert W. Brooks (#051), flight intercept trap ( MHNG, 1) .

REDESCRIPTION: Measurements (n=4): HW = 0.63 (0.57-0.65); TW = 0.61 (0.55-0.63); PW = 0.53 (0.49-0.57); SW = 0.56 (0.53-0.60); MW = 0.68 (0.64-0.71); AW = 0.59 (0.55-0.66); HL = 0.44 (0.40-0.46); EL = 0.13 (0.13-0.14); FL = 0.11 (0.11- 0.12); TL = 0.15 (0.12-0.16); PL = 0.39 (0.36-0.41); SL = 0.62 (0.58-0.66); SC = 0.60 (0.56-0.63); FB = 1.55 (1.46-1.61); BL = 2.80 (2.74-2.85) mm. Body predominantly 'unicoloured', with a darker head. Head very dark brown to black (front of clypeal region and supraantennal prominences appear lighter), pronotum reddish dark brown, elytra dark brown except shoulder area (poorly delimited) a tiny bit lighter (almost medium brown), darkening towards apex. Abdomen medium to dark brown, darkening towards apex. Legs, mouthparts and antennae medium to dark brown, legs sometimes yellowish, antennae sometimes slightly darkening from middle. Pubescence short and medium dense, much longer on abdomen.

Head and pronotum. Mid-antennal articles moderately elongate (antennomere 6 length:width = 0.062: 0.049 mm). Clypeus (Fig. 52) basally broad trapezoid, ratio of longitudinal distance of supraantennal prominence tip from eyefront to the same from clypeal front = 0.67-0.72. Infraocular ridge (Fig. 55) stronger anteriorly, finer posteriorly, terminating in a short keel at posterior edge of eye. Temple most strongly

FIGS 7-14

Parosus gigantulus sp. n.; maxilla (7), apex of maxillary palpus, coronal pegs (8), left mandible (9), basal part of right mandible (10), adoral surface of labium (11), hypopharynx (12), coronal pegs on median region of hypopharynx (13), left side of labrum (14). Scale bar = 0.005 mm for 8, 0.008 mm for 13, 0.04 mm for 12, 0.01 mm for 7, 11, 14, 0.16 mm for 9, 10.

curved in middle (therefore sometimes possibly appearing as slightly angled), eye strongly bulging from this arch. Pronotum (Fig. 53) with maximum width 1.59-1.64x base width, sides curved all the way, most strongly anteriorly, anterior angles slightly sharp (strongly curved sides near the angle). Clypeus and supraantennal ridges unpunctured, shiny. Vertex arcuately convex, occasional slight longitudinal depressions not breaking the arch of vertex. Frontoclypeal groove rather broad, but not so shallow. Posterior pronotal midline as a shiny, elevated, unpunctured stripe, continuing anteriorly in two fine vanishing lines. Two longitudinal depressions along sides of posterior midline, punctation mixed with microsculpture in them. Laterad (approximately at middle of these depressions) with two shiny, elevated spots. Pronotal sides with impressions around the middle. Head with 26-30 'longitudinal' puncture lines, pronotum with 20-24 'longitudinal' puncture lines, on mid- and anterior vertex loosened, pronotal punctation more sparse on lateral elevations.

Elytra and abdomen. Elytra (Fig. 54) slightly dilating posteriorly, with a moderately shiny appearance, punctured areas not separating sharply. Elytra bear two small, elongate, rather deep impressions behind the scutellum. Medially serrate fringe present on hind margin of tergite VII. Head, pronotum and elytra with similarly sized punctures, but elytral punctation not umbilicate, interspaces about 1/3-1/2 of puncture diameters. Very base of abdominal tergites (posterior to basal ridges) slightly scabrous, segments with very few scattered punctures. Aedeagus as in Fig. 40.

COMPARATIVE NOTES: Compared to P. skalitzkyi, the other species known from the Lesser Antilles, it has smaller, more bulging eyes, if there are depressions on the vertex, they do not form a longitudinal furrow and do not divide the vertex into halves. Similar to the slightly larger P. colombiensis , where the head punctation is more coarse.

DISTRIBUTION: The species is known only from the Lesser Antilles and adjacent coastal areas of Venezuela.

BIONOMICS: Unknown.

NOMENCLATURAL NOTE: P. antillarum was originally described in Parosus and would have had ending '-us' if treated as an adjective, thus it looks like it was deliberately formed as the genitive plural, meaning “of the Antilles”, and thus would not change with the gender of the genus it is placed in. In HERMAN (2001) the name is emended as P. antillarus, which is therefore an unjustified emendation that should be rejected.