Procloeon (Oculogaster) malabarensis sp. n., 2020

Kluge, Nikita J., 2020, Review of Oculogaster Kluge 2016 (Ephemeroptera, Baetidae, Procloeon Bengtsson 1915), Zootaxa 4820 (3), pp. 401-437 : 428-433

Procloeon (Oculogaster) malabarensis sp. n.

( Fig. 109–133 )

? Procloeon regularum: Sivaramakrishnan & Venkataraman 1990: 211 .

Etymology. The name refers to the historical area Malabar in India.

Material examined ( ZIN). Holotype: L-S-I ♀ { specimen [IX](11)2013}, INDIA, Karnataka, Shivamogga / Udupi districts near Agumbe , 25.I.2013, coll. N. Kluge & L. Sheyko. Paratypes: same locality and collectors, 11–31.I.2013: 2 L-S ♂ , 1 L/S ♂, 3 L-S ♀, 3 larvae; Kerala, Kottayam district, Erumeli , 18–21.I.2016, coll. N. Kluge, L. Sheyko: 3 L-S-I ♂ , 4 S-I ♂, 4 S ♂, 2 S-I ♀, 2 S ♀, 2 larvae.

Larva. CUTICULAR COLORATION. Head with brownish and colorless areas. Pronotum and mesonotum ocher or brownish with lighter and darker areas. Metanotum and thoracic pleura with colorless and brown areas, thoracic sterna colorless. Legs colorless or brownish, either unicolor, or with diffuse brown band in distal part of femur; tarsus darkened. Abdominal terga with maculation different on different segments; most or all terga with submedian pair of blanks, either corresponding to sigilla, or larger than sigilla; terga IV and VII more-or-less lighter than others; tergum VI darker than others ( Fig. 109 ). Abdominal sterna lighter than terga, either unicolor, or with lighter and darker areas. Caudalii ocher with posterior margin of every 4th segment brown ( Fig. 112 ).

HYPODERMAL COLORATION. Either absent or (just before moult to subimago) as in respective winged stages; male ( Fig. 109 ; as in Figs 127–129 ) and female (as in Figs 132–133 ) different.

SHAPE AND SETATION. Mouth parts as in Figs 113–117 ; maxillary palp 3-segmented, with 2nd and 3rd segments subequal ( Fig. 116 ). Femora with very small spine-like setae on outer and inner sides, with 2 spine-like apical setae located in plane of leg ( Fig. 110 ). Claws moderately long, in proximal part with two rows of minute denticles increasing distally ( Fig. 111 ). Hind protoptera completely absent. Abdominal segment IX with 3–7 lateral spines on each side, other segments without lateral spines; postero-lateral spines present on segments II–IX or III–IX, being minute on anterior segments. Posterior margin of abdominal tergum I with few sparse small spine-like pointed denticles; posterior margins of terga II–X with spine-like pointed denticles of unequal length; on all terga, including tergum IX, row of denticles not interrupted medially. Abdominal terga with short scales in wide semilunar or W-shaped non-opercula-bearing sockets, with sparse fine setae. Posterior margins of abdominal sterna I–IV or I–III smooth, posterior margin of sternum V or sterna IV–V with few minute denticles, posterior margins of sterna VI–IX and paraprocts with spine-like pointed denticles of unequal length. Abdominal sterna with sparse scales and sparse fine setae not forming regular rows. Tergalii widest near base, without dorsal lamellae; costal ribs without denticles (as in Figs 118–124 ). In distal part of cercus, spine on outer side of each segment as long as combined length of 2 next segments ( Fig. 112 ).

Subimago. CUTICULAR COLORATION. Cuticle either entirely colorless, or with postsubalar sclerite partly brown ( Fig. 130 ).

HYPODERMAL COLORATION. As in imago (see below, male and female).

TEXTURE. On fore leg of male and female 1st tarsal segment covered partly with microtrichia (as tibia), partly with pointed microlepides; all other tarsal segments entirely covered with pointed microlepides (as in Figs 105–106 ).

Imago, male ( Figs 128–129 ). Head ocher or whitish. Antenna with scapus and pedicellus non-pigmented, flagellum either non-pigmented, or brown. Turbinate eyes widened apically; either uniformly orange, or orange with yellow ring bordering facetted surface. Thorax ocher or whitish. Legs pale ocher. In paratype, ratio femur / tibia / tarsal segments (mm) on fore leg 0.80: 1.02: 0.03: 0.47: 0.30: 0.16: 0.12; on middle and hind leg 0.68: 0.68: 0.29: 0.10: 0.03: 0.11. Middle and hind legs without apical spine on 1st+2nd tarsomere, with single apical spine on primary 3rd tarsomere (as in Fig. 105 ). Wing with membrane colorless, veins ocher or brownish. Pterostigma with 1–3 oblique veins; marginal intercalary present in each interspace. Hind wing absent. Abdominal terga and sterna I–VI translucent, whitish, either without hypodermal markings, or with pair of small orange or red-brown submedian spots on tergum IV ( Fig. 127–129 ); lateral tracheae black. Most part of tergum VII and smaller part of tergum VIII red-brown; terga IX–X entirely white or ocher. Genitalia non-pigmented. Median projection of penial bridge truncated ( Fig. 125 ). Cerci whitish.

Imago, female ( Figs 131 ). Head moderately wide, distance between eyes subequal to eye length; eyes significantly elevated above head surface (as in Fig. 103 ). Head and thorax ocher, without brown spots, thorax sometimes with white markings. Legs as in male (see above); fore leg without apical spine on 2nd tarsomere, with single apical spine on primary 3rd tarsomere (as in Fig. 106 ); same on middle and hind legs (as in Fig. 105 ) (as in male). Wings as in male (see above). Abdomen ocher; terga II–VII laterally with contrastingly brown or black markings forming oblique stripes, often interrupted; markings on segments II, IV and VII larger than others ( Figs 131–133 ). Orange or red spots never present; white pigmentation between black markings either present ( Figs 131–132 ) or absent ( Fig. 133 ). Sterna II–VII or II–VIII laterally with dark brown or black markings in form of longitudinal interrupted lines or small spots (absent in young subimagines). Lateral tracheae colored with dark brown or black. Cerci whitish.

Egg. Without rigid chorion (viviparity).

Dimension. Fore wing length 3.5–4 mm.

Comparison. The new species P. (O.) malabarensis sp. n. is closely related to P. (O.) regularum , but it differs by smaller size, by truncated median projection of penial bridge and by hypodermal coloration of abdomen.

The difference in hypodermal coloration is better expressed in the female (that’s why the reared female imago is designated as the holotype). Females differ as follows (compare Figs 103–104 and 131–133 ): In contrast to P. (O.) regularum , whose winged females have paired reddish spots on terga IV and VII, females of P. (O.) malabarensis sp. n. have no such spots, but only brown or black lateral markings. The number and shape of the brown or black lateral markings also differs in these two species: In P. (O.) regularum such markings are present beginning from tergum I, but in P. (O.) malabarensis sp. n. they are present beginning from tergum II; in P. (O.) regularum markings on terga II–III and V–VI are integral and roundish, but in P. (O.) malabarensis sp. n. markings on these terga have form of oblique, narrow, interrupted lines. Dark brown or black markings on abdominal sterna are present in female imagines of P. (O.) malabarensis sp. n., but are absent in all 71 examined female imagines of P. (O.) regularum .

In winged males of P. (O.) malabarensis sp. n. the pair of reddish markings of abdominal tergum IV are limited to the median area of the tergum ( Fig. 127 ), while in P. (O.) regularum such markings are more or less wider expanded laterally ( Figs 99–102 ).

The last instar larva of P. (O.) regularum has paired reddish markings similar on terga IV and VII ( Fig. 89 ), that differs from the coloration of winged stages; the larva of P. (O.) malabarensis sp. n. has no such hypodermal markings; its hypodermal coloration appears just before moult to subimago, being the same as in the winged stages ( Fig. 109 ).

Distribution. Southern India.

Figures

FIGURES 109–112. Larvae of Procloeon (Oculogaster) malabarensis sp. n. 109, mature male larva (arrows show reddish hypodermal markings on abdominal terga VI and VII); 110, fragment of fore leg, focus on anterior side; 111, claw; 112, caudalii (110, 112, holotype).

FIGURES 113–117. Larva of Procloeon (Oculogaster) malabarensis sp. n. (holotype). 113, labrum (focus on dorsal side); 114–115, left and right mandibles; 116, maxilla; 117, labium (at left focus on dorsal side, at right focus on ventral side).

FIGURES 118–126. Procloeon (Oculogaster) malabarensis sp. n. 118–124, tergalii I–VII (holotype); 125, genitalia of male imago (muscles not shown); 126, their subimaginal exuviae.

FIGURES 127–133. Procloeon (Oculogaster) malabarensis sp. n. 127, abdominal terga III–V of male imago; 128–129, male imagines; 130, subimaginal exuviae of mesothoracic pleuron; 131, female imago; 132–133, abdomina of female imagines (133, holotype).

FIGURES 103–108. Females of Procloeon (Oculogaster) regularum. 103–104, imagines; 105–108, subimaginal exuviae: 105–106, middle and fore tarsi (arrows show spines; 1st–5th, initial tarsomeres); 107, half of mesonotum; 108, mesothoracic pleuron.

FIGURES 99–102. Male imagines of Procloeon (Oculogaster) regularum. 99–101, general view; 102, abdominal tergum IV.

FIGURES 84–89. Larvae of Procloeon (Oculogaster) regularum. 84–88, exuviae: 84, abdomen; 85–86, its caudalii; 87–88, fragment of middle part of cercus, with focus on lateral and median sides; 89, male larva.