Cloeon morna, Soldán, Tomáš & Bojková, Jindřiška, 2015

Soldán, Tomáš & Bojková, Jindřiška, 2015, New species of mayflies (Ephemeroptera) from Cape Verde, Zootaxa 3926 (4), pp. 561-575 : 562-566

Cloeon morna sp. n.

Male imago. Length: body 5.7–6.1 mm; forewings 4.8–5.1 mm; cerci 10.1–11.5 mm.

Head. Light brownish; antennae light brownish, apex of scape and pedicel markedly tinted with dark brown; flagellum as long as head and pronotum combined, translucent, light brownish near base ( Fig. 1 A). Turbinate eyes as tall as broad; facetted surface rounded, 1.3 times longer than wide, light yellow; shaft of same colour as facetted surface. Lateral eyes greyish-black; ocelli whitish, dark brown bordered.

Thorax. Pronotum yellowish brown, tinted with darker smudges posterolaterally ( Fig. 1 A). Mesonotum brownish with three lighter dorsal longitudinal stripes. Metanotum light brown, only posterior margin dark bordered.

Forewings unicoloured, transparent, except for dark brown bases of veins Sc and R. Costal and subcostal fields milky, not translucent. Pterostigma with 2–3 cross veins; no vein in costal field.

Legs whitish, claws of all legs distinctly brownish. Length ratio of foreleg segments from femur to tarsus: 7.9: 14.3: 6: 3.4: 1.6: 1; second segment of hind tarsus twice longer than third segment.

Abdomen. Abdominal terga whitish, not translucent ( Fig. 1 A). Terga of segments I–VI with light violet-brown markings forming two pale lateral stripes. Ventral side of body, forceps base and forceps whitish, unicoloured.

Forceps with conical basal segment, little longer than wide at base ( Fig. 1 B). Segment I almost completely fused with segment II, inner margin covered by dense fine setae. Ratio segment I/segment II 1:3.2. Segment II rounded and expanded apically. Segment III short, bent and as wide as one third of apical part of segment II. Genital plate (penis cover) wide and large (reaching almost half length of segment I), triangular, with rounded apex and slightly concave lateral margins ( Fig. 1 B).

Cerci white, with five brownish rings near base.

Female imago. Length: body 6.9–7.8 mm; forewings 5.7–6.9 mm; cerci 10.0–11.0 mm.

Head. Whitish yellow, with pair of dark bands along the frontoclypeal suture, diffused posteriorly, and with intense violet-brown smudge between ocelli ( Fig. 1 C). Distance between compound eyes three times wider than eye width. Scape whitish yellow, unicoloured; pedicel light brown in distal third; flagellum yellowish brown, darker at base.

Thorax. Pronotum whitish yellow, with pair of submedial, bent, violet brown stripes and large oblong-shaped brownish spots laterally ( Fig. 1 C). Mesothorax whitish yellow, with two brown longitudinal submedial bands and brown lateral parts. Metathorax whitish yellow, brown laterally.

Forewings translucent (except vitta), venation brownish. Pterostigma with 2–3 cross veins. Costal area milky, slightly darker in basal half of wing; subcostal area dark brown in basal half, yellowish brown in distal half ( Fig. 1 C). No cross veins near posterior margin of wings.

Legs whitish yellow, apical part of femora and basal part of tibiae slightly brownish; apical part of tarsal segments and shape claws of all legs brownish.

Abdomen. Abdominal terga whitish, tergal markings forming two wide lateral violet-brown stripes ( Fig. 1 C). Ventral side of body whitish, unicoloured.

Cerci white, with 5–6 dark brown rings near base (more intensive colour than in males).

Male subimago. Head. Head and antennae yellowish brown. Turbinate eyes whitish yellow, lateral eyes greyish black.

Thorax. Pronotum yellowish brown, unicoloured. Mesonotum with pale markings. Mesonotum whitish, unicoloured.

Forewings greyish, unicoloured, veins of same colour.

Legs whitish yellow, femora, tibiae and tarsi of same colour; claws of all legs darker.

Abdomen. Colour pattern of abdominal terga resembling that of males, but generally paler and more diffuse.

Cerci white, rings in basal part extremely faint.

Female subimago. Head. Yellowish brown, colour pattern as in female imago. Thorax. Pronotum and mesonotum yellowish brown, but with contrasting dark brownish markings. Metanotum whitish yellow, unicoloured.

Forewings milky, venation brownish; ciliae colourless, translucent. Colour pattern of vitta similar to female imago.

All legs with yellowish brown femora, but dark brown tibiae and tarsi.

Abdomen. Abdominal terga yellowish, tergal markings similar to female imago, but slightly darker; lateral violet brown stripes diffuse. Ventral side of body whitish, unicoloured.

Cerci brownish, lighter in distal part, ringed at base, similar to female imago.

Larva. Male larva body length: 4.0– 5.5 mm, cerci 2.5–3.8 mm; female larva body length: 4.2–6.0 mm, cerci 2.6–4.2 mm.

Head. Dark brown, with paler diffuse spots near antennal bases and on frons; epicranial suture conspicuously light bordered ( Fig. 1 D). Eyes light greyish, turbinate eyes dark red brownish. Lateral ocelli oval, dark brown, about three times longer than rounded frontal ocellus. Scape whitish, 1.5 times longer than pedicel; pedicel brownish.

Mouthparts. Dorsal surface of labrum ( Fig. 2 A) with scattered long pointed setae, shorter setae proximally; ventral surface with submarginal row of 6–9 small pointed setae; distal and lateral margins bordered with long plume-like setae.

Hypopharynx ( Fig. 2 B) with lingua rounded, densely covered by setae; superlinguae longer than lingua, rounded with apparent apex and densely covered by long marginal setae.

Right mandible ( Fig. 2 C) with two groups of incisors, inner with three rounded teeth and outer with four blunt teeth; prostheca asymmetric, with finger-like apex bent inside and three small teeth. Relatively sparse tuft of setae between prostheca and mola; outer margin of mandible straight or only slightly convex.

Left mandible ( Fig. 2 D) with two well-divided groups of incisors; outer group with four blunt teeth, inner group with four rounded teeth, two long and finger-like and two short and wide; left prostheca comb-shaped with three long sharply pointed projections on inner side. Dense tuft of long setae between prostheca and mola.

Maxillae ( Fig. 2 E) with three hooked teeth and dorsal row of medium subequal setae and ventral row of spinelike setae. Palps three-segmented, with segment I approximately 0.8 times length of segments II and III combined, segment II approximately 1.2x length of segment III. Surface of segments II and III with sparse long fine setae, apex of segment III with terminal seta with wide base.

Labium ( Fig. 2 F) with glossae subequal to paraglossae; margin of glossae with stout pointed setae, median part of glossae with 20–30 long pointed setae. Paraglossae dorsally and ventrally with a row of 7–8 long and stout setae parallel to inner margin, row of long pointed setae along inner margin (apical ones longest and stout), five long and pointed setae medially in apical part of paraglossae and scattered fine setae at lower part of paraglossae. Labial palps three-segmented, with segment I approximately 0.8x length of segments II and III combined, segment II approximately 0.8x length of segment III. Segment III tapered (ratio length/width =1.5), with concave inner margin bearing row of long setae and irregular row of stout pointed setae submarginally. Segment II with 4–5 subapical stout setae.

Thorax. Pronotum dark brown, with pair of diffuse posterolateral spots, medial suture with light border ( Fig. 1 D). Mesonotum of same colour, with lighter diffuse smudges and pair of pale spots near bases of fore wing pads. Pleural part of thorax and coxae brownish, unicoloured; legs pale brownish; femora with subapical diffuse darker band; tibiae slightly darker near bases; tarsi unicoloured.

Forelegs. Dorsal surface of femora with pointed spines along front and hind margin and irregular row of pointed spines medially in proximal half of femora ( Fig. 3 D). Dorsoapical patch of setae formed by 4–5 spines. Tibiae and tarsi almost bare dorsally, only with stout pointed spines along hind margin. Subproximal arc of thin setae on tibiae absent. Tarsal claws slender and relatively long (0.4x length of tarsi) with two rows of about 18 acute teeth increasing in length apically.

Abdomen. Terga dark brown, with paler anterolateral parts and pair of light spots medially ( Fig. 1 D). Spots more or less diffuse, in some specimens even elongated and divergent. Sterna yellowish brown; sterna I–VIII with wavy line-shaped, dark markings in anterolateral areas.

Posterior margin of abdominal terga with teeth of three sizes and shapes: large and wide acute teeth relatively regularly alternating with those shorter of about one third and sparse small (one fourth length of large teeth) and acute teeth ( Fig. 4 A). Lateral margins of segment VIII with 4–5 spines and segment IX with six spines; other segments only with anterolateral teeth ( Fig 4 C).

Gills on segments I–VI with two lamellae. Dorsal lamella of gill I tongue-shaped, symmetric, reaching nearly distal margin of ventral lamella; ventral lamella nearly symmetric, roughly triangular with rounded distal margin, slightly longer than wide ( Fig. 3 A). Dorsal lamella of gill III triangular with rounded distal margin; ventral lamella roughly circular ( Fig. 3 B). Gill VII single and asymmetric ( Fig. 3 C).

Cerci and paracercus about subequal in length to abdomen; yellow, posterior part darker; with conspicuous brown rings on every fourth segment. Cerci with abundant thin setae on inner margins.

Type material. Holotype: male imago reared from larva, with its larval and subimaginal skins; Santo Antão, Ribeira da Torre, Xôxô; 17°08'23.9'' N / 25°04'00.2'' W; 190 m a.s.l.; 7.v.2013.

Paratypes: 3 male imagines, 3 male subimagines, 10 female imagines, 1 female subimago, 72 larvae; same data as holotype.

2 male subimagines, 7 female imagines, 2 female subimagines, 9 larvae; Santo Antão, Ribeira Tarrafal, Tarrafal de Monte Trigo; 16°57'36.0'' N / 25°18'33.0'' W; 20 m a.s.l.; 13.v.2013.

2 larvae; Santo Antão, Ribeira do Paul, Eito; 17°08'24.0'' N / 25°05'25.9'' W; 140 m a.s.l.; 7.v.2013.

18 larvae; Santo Antão, unnamed levada, Banco de Areia; 17°06'23.6'' N / 25°15'51.1'' W; 280 m a.s.l.; 9.v.2013.

4 larvae; Santo Antão, Ribeira da Garca, Manta Velho; 17°06'11.2'' N / 25°09'26.2'' W; 580 m a.s.l.; 10.v.2013.

2 larvae; Santo Antão, unnamed brook, Janela; 17°07'18.6'' N / 24°59'42.1'' W; 10 m a.s.l.; 10.v.2013.

Etymology. The species is named after the famous Cape Verdean music genre " morna ", which typically talks about departure abroad and love for the homeland and sea (the need to leave and the desire to stay).

Biology. Most larvae were collected in brooks with open flowing water ( Fig. 8 A), occasionally in little trickles flowing through fields of taro ( Colocasia esculenta ) ( Fig. 8 C, E). All brooks were small (from several centimetres to one meter wide) and very shallow ( Fig. 8 A). Larvae inhabited coarse substrate (gravel and small stones) in marginal parts of riffles, not directly the streamline, and they were not found in pools. Artificial habitats (e.g. levadas in Banco de Areia) were occasionally inhabited too, but only in parts with a gravel bottom, never in parts with a uniform concrete bottom with rapidly flowing water. Abundance of larvae was very different at the localities studied. While larvae were the dominant benthic insects at the type locality, they occurred only individually at other localities. At the type locality, larvae of Cloeon morna sp. n. were accompanied by numerous larvae of the dragonfly Crocothemis erythraea (Brullé, 1832) occurring in different instars and rarely with larvae of Anax imperator Leach, 1815 , the caddisfly Cheumatopsyche antoniensis Malicky, 1983 and the whirligig beetle Dineutus aereus (Klug, 1834) , which imagines occurred in large flocks in pools.

Subimagines emerged during the late afternoon and evening and moulted to imaginal stage next morning. Shortening of the subimaginal life-span and its shifting to the night period represents an adaptation of Cloeon species living in arid areas to avoid high day temperatures and low humidity and also to avoid predation pressure (Soldán 1987). Swarming of imagines took place in the evening at dawn and swarms flew very high, above banana plants. Females were observed to oviposit in the morning.

Figures

FIGURE 1. Cloeon morna sp. n.: A—male imago; B—male genitalia, ventral view; C—female imago; D—larva.

FIGURE 2. Cloeon morna sp. n., mouthparts: A—labrum (left ventral view, right dorsal view); B—hypopharynx; C—right mandible; D—left mandible; E—right maxilla; F—labium.

FIGURE 3. Cloeon morna sp. n., larva: A—gill I; B—gill III; C—gill VII; D—fore leg.

FIGURE 4. Distal margin of abdominal tergum IV (scale bar 0.05 mm): A— Cloeon morna sp. n.; B— Cloeon sidadi sp. n. Lateral margin of abdominal terga VIII and IX: C— Cloeon morna sp. n.; D— Cloeon sidadi sp. n.

FIGURE 8. Aquatic habitats in the islands of Santo Antão and Santiago. A—Ribeira da Torre in Xôxô (type locality of Cloeon morna sp. n.); B—pools of Ribeira Tarrafal in Tarrafal de Monte Trigo; C—irrigation system of taro fields common in Santo Antão; D—irrigation cistern in the valley of Ribeira Grande in Cidade Velha (type locality of Cloeon sidadi sp. n.); and E—an unnamed brook in Fontainhas.