Procloeon (Pseudocentroptilum) caspicum Sroka

Bojkova, Jindriska, Sroka, Pavel, Soldan, Tomas, Namin, Javid Imanpour, Staniczek, Arnold H., Polasek, Marek, Hrivniak, Ľubos, Abdoli, Ashgar & Godunko, Roman J., 2018, Initial commented checklist of Iranian mayflies, with new area records and description of Procloeoncaspicum sp. n. (Insecta, Ephemeroptera, Baetidae), ZooKeys 749, pp. 87-123 : 92-96

Procloeon (Pseudocentroptilum) caspicum Sroka sp. n.

Diagnosis

(based on larvae and eggs). Labrum with pronounced medial notch, anterior margin laterally from medial notch strongly asymmetric; mandible incisor groups separated at distal third of their length; maxillary palps three-segmented, not thickened, length of segment III of maxillary palp reaches 0.5 × segment II length; fully developed hind wing pads; length of tarsal claws 0.44 × tarsus (forelegs); 0.55 × tarsus (middle and hind legs); lateral spines present on abdominal segments VIII–IX; single gill plates with rudimental dorsal lamella; inner margin of paraproct with approximately 8-11 large teeth; egg chorion without equatorial band of large papillae.

Description.

Mature larva. Body length 7-8 mm, length of antennae approximately 2 mm, length of cerci 2-3 mm (0.3 × body length). General colouration yellowish with darker brownish pattern (Figs 2, 3).

Head. Labrum (Fig. 4) approximately 1.3 × broader than long, anterior margin with pronounced medial notch. Anterior margin laterally from medial notch strongly asymmetrically rounded. Along anterior margin, row of bifurcated setae situated anterolaterally and shorter, stout setae anteromedially. Dorsal surface with scattered hair-like setae, not arranged in rows; ventral surface with group of hair-like setae medially. Mandible incisors (Figs 5, 6) divided into two groups, separated at distal third of their length. Each group with 3-4 rounded denticles. Left prostheca broadened apically, with approximately three blunt teeth and four longer sharp teeth (Fig. 5); right prostheca not broadened apically, with approximately three blunt teeth and one longer sharp tooth (Fig. 6). Group of long setae present between incisors and molar area. Maxillary palps (Fig. 7) 3-segmented, second slightly shorter than first segment. Third segment approximately half as long as second segment, apically tapering, bluntly pointed, without scales. Maxillary palps sparsely covered with tiny hair-like setae. Labial palps 3-segmented (Figs 8, 10), third segment with rounded angles and straight margin apically. Ventral side of first and second segment with scattered hair-like setae, third segment with several longer and thicker setae (particularly along apical margin) and numerous hair-like setae (Fig. 8). Dorsal side of second segment with group of 4-7 long setae, otherwise dorsal side of all segments without setae (Fig. 10). Glossae as broad as paraglossae, paraglossae slightly longer. Paraglossae ventrally with single irregular submarginal row of setae along inner margin, basal parts of glossae and paraglossae with sparse groups of long hair-like setae (Fig. 9). Glossae and paraglossae dorsally with rows of setae along margins (longer setae on paraglossae, shorter on glossae), denser setation apically, one additional irregular row of long setae in median portion of paraglossae (Fig. 11).

Thorax. Prothorax approximately 3 × broader than long, whitish, with darker brownish pattern (Fig. 2). Mesothorax of same colour, metathorax darker posteriorly. Hind wing pads fully developed (Fig. 16). Legs pale yellowish, femora with darker brown smudges distally. Tibiae darker in proximal portion, tarsi darkened proximally and distally. Femora with oblique transversal row of hair-like setae subapically, extending to outer margin (Fig. 15). Curved row of hair-like setae proximal to tibio-patellar suture along outer margin of tibia (Fig. 15). Tarsi with sparse row of hair-like setae along outer margin in basal half of tarsus. Claws brownish, with numerous minute teeth arranged in two parallel rows, reaching approximately 2/5 of claw length (Fig. 29a, b). Measurements of individual leg segments (femur: tibia: tarsus: claw): 1.15: 0.68: 0.71: 0.27 mm in foreleg, 1.18: 0.67: 0.65: 0.29 mm in middle leg, 1.18: 0.66: 0.64: 0.29 mm in hind leg (averages from six individuals).

Abdomen. Terga whitish, with dark spots forming clear pattern (Figs 2, 3). Terga I–VIII with dark spot posterolaterally (on segments I–VII near respective gill insertion). Tergum I with dark stripe on posterior margin. Tergum II with distinct dark patch medially, wide band (sometimes interrupted in middle) along anterior margin and thinner stripe on posterior margin, fused with enlarged smudges situated posterolaterally. Tergum III similar to tergum II, band along anterior margin more distinct, sometimes fused with posterolateral smudges. Tergum IV pale, with thin stripe on posterior margin and indistinct smudges medially and laterally. Terga V–VI with dark patch medially and dark stripe on posterior margin, fused with enlarged smudges situated posterolaterally. Tergum V also bears distinct dark band along anterior margin, connected to posterolateral smudges. Tergum VII with thin dark stripe on posterior margin and slightly wider stripe along anterior margin, interrupted in middle. Tergum VIII with wide dark band along posterior margin. Tergum IX with thin dark stripe on posterior margin and wide dark band anteriorly (most dark areas on anterior margin and laterally). Tergum X with dark stripe on posterior margin. Sterna pale whitish with dark patches sublaterally and dark stripe on posterior margin. Distinctiveness of this pattern increasing in more posterior segments. Sterna VIII–IX all dark smudged. Surface of abdomen covered with numerous scales and scale bases (Fig. 30); similar scales also on legs and other body parts. Posterior margin of abdominal terga I–IX with large teeth accompanied by smaller ones (Figs 25, 30). Teeth on tergum X smallest medially, lateral teeth slightly longer (Fig. 26). Segments II–VII with 1-2 prominent posterolateral spines near gill bases, sometimes accompanied by few smaller ones. Lateral spines present on segments VIII–IX (Fig. 17). Gills (Figs 18-24) whitish, with distinct tracheization. All gills simple, vestigial dorsal lamella present. Gills asymmetric and apically rounded. Paraproct (Fig. 27) with approximately 8-11 large teeth accompanied with scarce smaller ones on inner margin. Ventral surface of paraproct plate covered with scales, scale bases, and tiny hair-like setae. Caudal filaments reaching approximately 1/3 of body length, yellowish, with dark brownish stripe in middle. Paracercus slightly shorter than cerci. Ring of small triangular spines at each articulation of caudal filaments, alternated with larger spines every fourth segment (Fig. 31, these larger spines accompanied by dark brown stripe and distinction more pronounced in basal part of filament). Articulations further equipped with flattened scales and scale bases. Long swimming setae along inner margin of cerci and on both margins of paracercus. In basal third of filaments swimming setae only scarce, apically only last one or two segments without setae. Outer margin of cerci with enlarged, long, and thick spines on distal segments, longer than corresponding segment (Fig. 28).

Egg.

Oval shaped; 130-140 µm long, 65-75 µm wide. Chorionic surface covered with thick reticulated ridges forming irregular polygonal mesh (Fig. 32a, b). Each polygon with coiled knob-like thread.

Imago and subimago.

Unknown.

Type material.

Holotype. Female mature larva, IRAN, Chelvand River above Chelvand (S of Lavandvil), approximately 2.5 km from its inflow into Caspian Sea, -6 m a.s.l., 38°17'20"N, 48°51'35"E (locality 27), 19.5.2016.

Paratypes. 1 male, 7 female larvae (3 specimens mounted on slides), same locality as holotype; 1 female larva, IRAN, Sefidab River in Divresh (SE of Shirkooh), 273 m a.s.l., 36°53'59"N, 49°35'06"E (locality 7), 13.5.2016; 1 female larva, IRAN, Karganrud River in Talesh, ca 7 km from its inflow into the Caspian Sea, 36 m a.s.l., 37°48'22"N, 48°54'27"E (locality 36), 22.5.2016.

All types deposited in the collection of the Biology Centre, Czech Academy of Sciences, Institute of Entomology, České Budějovice, Czech Republic.

Etymology.

The species name refers to the proximity of the type locality to the Caspian Sea.

Habitat.

Larvae were found in three different stream habitats, two eutrophic streams of different size (Chelvand and Karganrud rivers) in the Caspian Sea coastal plain relatively close to their inflow to the sea and one small, clear and cold brook in the forest. Chelvand at the type locality is a small river with coarse stony substratum rapidly flowing from the hills to the plain so it partially keeps its mountainous charac ter also in low altitude (-6 m a.s.l.). Procloeon caspicum sp. n. larvae co-occurred with numerous larvae of Serratella elissa , Baetis vardarensis and Caenis macrura , and less numerous Epeorus (Caucasiron) spp., Rhithrogena cf. decolorata . Karganrud in Talesh is a warm river flowing in the urban and agricultural area with wide flat alluvium and stony-gravel substratum. Bottom substrate had rich cover of green filamentous algae. Procloeon caspicum sp. n. co-occurred with numerous larvae of Rhithrogena cf. decolorata , Oligoneuriella tskhomelidzei , Baetis vardarensis , Baetis rhodani , and less numerous Baetis fuscatus and Serratella elissa . Sefidab, the third and completely different stream, is a small cold brook entirely shaded by forest with coarse stony bottom and alternating pools and riffles. Procloeon caspicum co-occurred with numerous larvae of Epeorus (Caucasiron) cf. znojkoi , Electrogena pseudaffinis , Baetis baroukianus and less numerous Serratella elissa and Habroleptoides confusa .