Procloeon (Pseudocentroptilum) fascicaudale ( Sowa, 1985 )

Sroka, Pavel, Godunko, Roman J. & Soldán, Tomáš, 2010, Redescription of the species Procloeon (Pseudocentroptilum) fascicaudale (Sowa, 1985) (Ephemeroptera: Baetidae) with notes to its taxonomic position, biology and distribution, Zootaxa 2490, pp. 16-32 : 18-26

Procloeon (Pseudocentroptilum) fascicaudale ( Sowa, 1985)

( Figs 2–31 )

Pseudocentroptilum fascicaudale Sowa, 1985 : Acta Hydrobiol., 27 (1): 75

Pseudocentroptilum fascicaudale Sowa, 1985 : apud Belfiore & D'Antonio, 1990, Acta Entomol. Bohemoslov., 87: 117 [grouping in P. m o t a s i species-group]

Procloeon (Pseudocentroptilum) fascicaudale ( Sowa, 1985) : apud Jacob, 1991, Verh. Westd. Entom. Tagung, 1990: 275 [subgeneric status, new combination]

Pseudocentroptilum fascicaudale Sowa, 1985 : apud Bauernfeind, 2003: Res. Update of Ephemeroptera & Plecoptera, Univ. Perugia , Italy: 101 [check-list, Greece]

Male imago. Body length 6.9–7 mm, forewing length 5.5–5.6 mm, cerci length 11 mm (1.6 times longer than body).

Head ( Figs. 2, 3 ) brown, turbinate eyes moderately high, facetted surface elongated, 1.5 times longer than wide. Coloration of the facetted surface ochraceous, bordered with thin yellowish stripe. Shaft pale brownish, darker at the base.

Prothorax brown; meso- and metathorax dark brownish-olive. Forewing transparent, pterostigma whitish, with 4–6 cross veins and single marginal intercalaries. Hind wing ( Figs. 6 ) transparent, with rounded apex. Width slightly expanded at 3/5 of its length. Two longitudinal veins are present; cross veins very rarely occur. Costal projection well developed and hooked. Legs pale brown, with darker articulations. All legs with one sharp and one blunt claw. Foreleg with 4-segmented tarsus. Middle and hind legs with 3-segmented tarsus, first (basal) segment only indicated (legs measurements on Table 1 ).

Abdomen pale brown, dorsal surface darker. Sometimes with paler pattern near the anterior margin of some individual terga and darker areas laterally. Abdominal segments I–VI (VII) semitransparent, other segments darker. Cerci pale, yellowish-white, covered with tiny hairs. Articulations dark brown. Every second (more distally every fourth) articulation darker and more distinctive. Distal 1/3 of cerci entirely without dark articulations.

Forceps ( Fig. 4 ) brownish, 4-segmented. First (basal) segments 1.5 times broader than long, separated from each other only by a very narrow interspaces. Second segment 1.3 times broader at its base than long. First and second segments narrow distally, mainly on the inner sides. Third segment slender, curved inwards, slightly extended at the apex. Fourth segment relatively small, 2 times longer than broad, curved, extended at the apical part. Lengths of individual forceps segments (averages from 6 specimens) in mean: first segment – 0.165 mm; second segment – 0.098 mm; third segment – 0.356 mm; fourth segment – 0.07 mm. Subgenital Characters Foreleg (mm) Middle leg (mm)* Hind leg (mm)*

*Remark: segment I of middle and hind legs is fused with tibia.

Female imago. Body length 6.5–7 mm, forewing length 6–7.5 mm, cerci length 10 mm (1.6 times longer than body). Coloration similar to male, slightly paler. Distance between compound eyes 1.7 times eye width, approximately equal to the eye length (dorsal aspect).

Forewing transparent. Pterostigma whitish, with 4–6 cross veins and single marginal intercalaries. Hind wing ( Fig. 7 ) transparent, with rounded apex. The shape is similar to male imago, but slightly narrowed. Hind wing with two longitudinal veins and without apparent cross veins. Width slightly expanded at 3/5 of wing length. Well developed hooked costal process. Legs pale brown, with darker articulations. All legs with one sharp and one blunt claw. Foreleg with 4-segmented tarsus, middle and hind legs with 3-segmented tarsus; first (basal) segment only indicated (legs measurements on Table 1 ).

Abdomen pale brown, not transparent. Dorsal surface darker, sterna pale whitish, sometimes with paler pattern near the anterior margin of individual terga and darker areas laterally. Abdominal segments I–VI (VII) semitransparent, other segments darker. Cerci of the same type as male.

Male subimago. Body length 6.5–7 mm, forewing length 5 mm, cerci length 7–8 mm (1.1 times longer than body) General body coloration pale brownish.

Head brown, turbinate eyes lower and paler than in imago, without interspaces between them. Thorax brown (prothorax), or dark olive-brownish (meso- and metathorax). Wings dull, posterior margin with row of tiny hairs. Forewing with single marginal intercalaries. Legs pale brown, with darker articulations. All legs with one sharp and one blunt claw. Foreleg with 4-segmented tarsus, middle and hind leg with 3-segmented tarsus. First (basal) segment only indicated (legs measurements in the Table 2 ).

*Remark: segment I of middle and hind legs is fused with tibia.

Abdomen brown, unicolorous, not transparent, apparently darker distally. Thin dark stripe on the anterior margin of individual terga. Cerci pale, yellowish-white, covered with tiny hairs. Articulations at the distal half dark brown.

Female subimago. Body length 6–6.5 mm, forewing length 5.5–6 mm, cerci length 7.5–8 mm (1.1 times longer than body). General body coloration pale brownish.

Head brownish, distance between compound eyes 1.3 times eye width, approximately 0.9 times eye length (dorsal aspect). Prothorax with darker margins, mesothorax pale yellowish with darker suturae. Forewing dull, posterior margin with row of tiny hairs. Pterostigma with 4–6 cross veins and single marginal intercalaries. Hind wing dull, with rounded apex. Legs pale brown, with darker articulations, tarsal segments and claws. All pairs with one sharp and one blunt claw. Foreleg with 4-segmented tarsus, middle and hind leg with tarsus 3- segmented, first (basal) segment only indicated (legs measurements on Table 2 ).

Abdomen not transparent, terga with apparent transversal dark lines along anterior margin, sterna pale yellowish. Cerci ringed to more than half their length, covered with short, dense hairs.

Mature larva (male and female). Body length 6.5–8 mm, cerci length 2.7–3 mm. General body color yellowish, with darker brownish pattern on thorax and abdomen.

Head light yellowish, antennae reaching past prothorax. Compound eyes black, in male larvae apparent yellowish turbinate eyes. Labrum ( Figs. 8, 9 ) approximately 1.3 times broader than long, slightly expanded anteriorly, anterior margin with wide medial incurvation. Along the anterior margin different types of setae can be distinguished: simple, long, thin setae and fringed setae situated anterolaterally, two types of stout setae anteromedially. Dorsal surface with several tiny bristles and hairs, not arranged in rows; ventral surface with groups of hairs medially. Mandible incisors ( Figs. 10, 11 ) divided into two groups, separated in distal third of their length. Each group with 3–4 rounded teeth. Left prostheca broadened apically, with approximately 3 blunt teeth and 4 longer sharp teeth ( Fig. 10 ); right prostheca pointed, with only one blunt tooth subapically ( Fig. 11 ). Between incisors and molar area of right and left mandibles a group of long setae. Maxillary palps ( Fig. 12 ) 3-segmented, first and second segments approximately equal in length, third (apical) segment nearly as long as 1/2 of the second segment, apically rounded, without scales. Surface of maxillary palps covered with sparse tiny hairs. Hypopharyngeal superlinguae bent inwards, lingua distinctly broader, tapered proximally. Labial palps 3-segmented ( Figs. 13, 14 ), second and third segments well distinguished; third segment straight, with rounded angles and rows of robust setae. Ventral surface of first and second segment covered with occasional hairs, third segment with several setae and numerous tiny hairs ( Fig. 13 ). Dorsal side of the second segment with the group of 4–6 long setae, otherwise dorsal surface of all segments without any hairs or setae ( Fig. 14 ). Glossae as broad as paraglossae, paraglossae slightly longer. Paraglossae dorsally with long marginal and submarginal setae arranged into several irregular rows on the apical portion and along the outer margin; a single regular submarginal row of setae along inner margin. Basal part of glossae with a group of bifurcated setae and regular submarginal row of short spines/setae along margins.

Prothorax approximately 2.4 times broader than long, whitish, with pale brownish darkening along the anterior margin, interrupted in the middle. Mesothorax of the same color pattern, or with two more indistinct smudges in the middle in some specimens. Mesothorax sometimes with apparent dark tracheization. Metathorax generally pale brownish. Legs pale, yellowish-brown, darker at the distal portions of all segments. Inner margins of tibiae and tarsi with a row of short setae. Claws ( Figs. 24, 25 ) brownish, darker at the base, with numerous small teeth arranged in two parallel rows, reaching approximately 2/5 of the claw length (legs measurements in the Table 3 ).

Abdomen pale, whitish, with dark spots forming various patterns ( Figs. 30, 31 ) on the terga. Most variable are segments II and III. Figures presented show only utmost forms, large scale of transitory forms have been observed. Segment I always pale, with only thin darker stripes along anterior and posterior margins. Several isolated dark spots can occur on segment II (large central spot, connected to thin dark stripe along posterior margin, two oval-shaped spots situated more laterally near anterior margin and further lateral spots situated near gill bases). Central dark spot can extend sideward and fuse with other spots situated anterolaterally. However, pale areas between central part and gill bases are still left posteriorly. Segment III frequently with wide oblong-shaped band, extending transversally between gill bases, almost reaching anterior margin and in the middle forming enlarged part pointing backwards. This pattern can be somewhat modified mainly at posterior part of tergite, where dark smudges can appear. In case of such arrangement, central part of tergite is paler than in case of single dark band and thin oblique pale spots are present there. On segment IV, two transversal dark spots are situated along anterior margin, otherwise without any distinct coloration. On segment V, two dark spots anteriorly as on previous segment, accompanied by a pair of similar spots along posterior margin. Rest of tergite more or less darkened, except for central part and areas near lateral margins. Segment VI dark with pale spots in the middle and near lateral margins. Segment VII generally pale, darker anteriorly, with two minute paler spots in the middle. Segment VIII very pale, with darker area along anterior margin. Segment IX with darker stripes near all margins. Segment X pale, almost without any dark pattern. Surface of abdomen covered with numerous scales, slightly serrated apically ( Fig. 23 ); similar scales also on legs and other body parts. Posterior margins of abdominal terga with large teeth alternating with much smaller ones ( Fig. 22 ). Segments II–X with 1–2 posterolateral spines near gill bases. Lateral spines of posterior abdominal segments arranged as follows: segment VIII: 5–7, segment IX: 7–10 and segment X: 5–10 spines (or, more precisely, spine pairs).

Paraproct ( Fig. 26 ) with approximately 8–12 large teeth accompanied with several (up to 12) smaller ones on posteromedial margin. Ventral surface of paraproct plate covered with scales.

Gills ( Figs. 15–21 ) whitish, tracheization indistinct. Gill pairs I–VI double, asymmetric, dorsal lamella relatively large in proximal gill pairs, however even there not larger than 1/2 of the ventral lamella. Ventral lamella always longer than respective segment. Outer margin in gill pairs I–V very slightly convex or almost straight in the basal half, concave in the distal half of their length. Outer margin of gill pair VI with straight or slightly concave basal half and strongly concave distal half. Gill pair VII with outer margin strongly concave. Inner margin of all gill pairs strongly convex: in gill pairs I–VI mainly in basal half, in gill pair VII mainly in the middle part. Only gill pair VII with concavity of the outer margin more developed than convexity of the inner one. All gills rounded or bluntly pointed apically, only gill pair VII pointed in some specimens.

Caudal filaments ( Fig. 27 ) yellowish-brown, reaching approximately 2/5 of the body length, with long pilosity on the inner side. Ring of small spines at each articulation of caudal filaments, alternated with larger spines every fourth segment in basal 2/3 of filaments (these larger spines accompanied by dark brown stripe). Paracercus as long as cerci (or very slightly shorter), with pilosity on both sides. Only last two or three segments of caudal filaments without setae. Each article of caudal filaments with long spine laterally.

Egg. The eggs measured approximately 200 µm in length and 110 µm in width. General shape oval, with rounded poles ( Fig. 28 ). Chorionic surface covered by reticulation of polygonal structures ( Fig. 29 ). Each polygon includes central projection (“papilla” according to Keffermüller & Sowa 1984; Gaino & Bongiovanni 1992). Papillae consisted of thinner stalk and larger apical knob. Longitudinal (meridional) rows comprise about 40–42 papillae, transversal rows 22–26 papillae.

Figures

FIGURES 2 – 7. Procloeon (Pseudocentroptilum) fascicaudale (Sowa, 1985), male (2 – 6) and female (7) imagines: 2, head (lateral view); 3, head (dorsal view); 4, forceps (ventral view); 5, subgenital plate (ventral view); 6 – 7, hind wing.

FIGURES 8 – 14. Procloeon (Pseudocentroptilum) fascicaudale (Sowa, 1985), mature larvae: 8, labrum (dorsal view); 9, labrum (ventral view); 10, left mandible (dorsal view); 11, right mandible (dorsal view); 12, maxilla (dorsal view); 13, labium (dorsal view); 14, labium (ventral view).

FIGURES 15 – 21. Procloeon (Pseudocentroptilum) fascicaudale (Sowa, 1985), mature larvae: 15, gill I; 16, gill II; 17,

FIGURES 22 – 29. Procloeon (Pseudocentroptilum) fascicaudale (Sowa, 1985), mature larvae: 22, posterior margin of abdominal tergite (dorsal view); 23, surface of abdominal tergite (dorsal view); 24, tarsal claw (dorsal view); 25, surface of tarsal claw (dorsal view); 26, paraproct plate (dorsal view); 27, segments of caudal filament (dorsal view); 28, egg (general view); 29, surface of egg (details).

FIGURES 30 – 31. Procloeon (Pseudocentroptilum) fascicaudale (Sowa, 1985), mature larvae: 30 – 31, variability of abdominal terga coloration.

Tables

TABLE 1. Morphometrics of imagines legs of Procloeon (Pseudocentroptilum) fascicaudale (Sowa, 1985). Values are averages from 6 male and 3 female specimens.

	male	female	male	female	male	female
Femur Tibia	1.31 1.53	1.06 0.86	1.27 1.20	1.15 1.14	1.11 1.09	1.09 1.12
Tarsus (whole)	1.86	0.76	0.36	0.38	0.36	0.36
Segment I Segment II	0.87 0.57	0.29 0.17	- 0.16	- 0.17	- 0.16	- 0.16
Segment III	0.36	0.14	0.14	0.14	0.14	0.14
Segment IV	0.21	0.21	0.17	0.20	0.20	0.19

TABLE 2. Morphometrics of subimagines legs of Procloeon (Pseudocentroptilum) fascicaudale (Sowa, 1985). Values are averages from 2 male and 9 female specimens.

Characters	Foreleg (mm) male female	Middle leg (mm)* male female	Hind leg (mm)* male female
Femur	1.11 1.04	1.04 1.15	1.11 1.07
Tibia Tarsus (whole)	0.86 0.81 1.00 0.75	1.12 1.14 0.36 0.38	1.09 1.12 0.36 0.37
Segment I	0.39 0.31	- -	- -
Segment II Segment III	0.24 0.20 0.18 0.14	0.16 0.16 0.14 0.14	0.16 0.16 0.13 0.14
Segment IV	0.20 0.21	0.16 0.19	0.16 0.19

TABLE 3. Morphometrics of larval legs of Procloeon (Pseudocentroptilum) fascicaudale (Sowa, 1985). Values are averages from 12 mature larvae.

Characters Femur	Foreleg (mm) 1.22	Middle leg (mm) 1.29	Hind leg (mm) 1.27
Tibia	0.69	0.77	0.74
Tarsus Tarsal claw	0.77 0.35	0.76 0.36	0.76 0.38