Sangpradubina, Boonsoong, Boonsatien & Sartori, Michel, 2016

Boonsoong, Boonsatien & Sartori, Michel, 2016, Sangpradubina, an astonishing new mayfly genus from Thailand (Ephemeroptera: Leptophlebiidae: Atalophlebiinae), Zootaxa 4169 (3), pp. 587-599 : 588-591

publication ID	https://doi.org/ 10.11646/zootaxa.4169.3.11
publication LSID	lsid:zoobank.org:pub:982AADB9-A2A3-4E61-9B23-9C85BF044200
DOI	https://doi.org/10.5281/zenodo.6075150
persistent identifier	https://treatment.plazi.org/id/03C287AC-2B3E-FFAB-FF36-53F9FCA519A6
treatment provided by	Plazi
scientific name	Sangpradubina
status	gen. nov.

Treatment

Sangpradubina gen. nov.

Type species: Sangpradubina thailandica sp. nov. by present designation

Mature nymph. Head: Head prognathous. Labrum with 5 flat denticles in anterior emargination. Mandible with tuft of long setae in middle of lateral margin. Maxillae with one comb-shaped dentiseta, and with well-developed anterolateral projection, as long as dentiseta; palp 3-segmented. Hypopharynx with superlingua well-developed laterally; lingua with pair of lateral processes near base and pointed distally. Labium with glossae dorsal to paraglossae; labial palp 3-segmented. Thorax: Fore- and middle femora each with dense rows of long setae on outer margin. All legs without tibio-patellar suture, but with stout setae on outer margin of femur and stout bristles scattered on dorsal surface. Claws stout, hooked and narrowed apically, 4 denticles at base and 9 at apex. Abdomen: Posterolateral spines present on segments 6–9. Abdominal gill 1 single, consisting of slender lamella; gills 2–7 alike, dorsal and ventral lamellae plate-like, apical half of each lamella with fringed margins. Caudal filaments with whorls of thin setae on each articulation.

Imago. Head: Eyes of male meet on meson. Thorax: Tibio-patellar suture absent on forelegs, present on middle and hind legs. Tarsal claws of all legs similar, one apically hooked, other obtuse, pad-like. Forewing with vein MA symmetrically forked, vein MP not forked; MP2 independent of vein MP1; 5 intercalaries between CuA and CuP. Hind wings with rounded apex, costal margin convex, with weakly developed projection. Abdomen: Male genitalia with forceps 3-segmented, styliger strongly convex; penes lobes stocky, with widest part at base; gonopore ventral, in subapical position. Female subanal plate distally narrow and rounded, with small cleft at apex.

Egg. General shape elongated, chorionic surface with uniform longitudinal ridges, each ridge with distinct groove between ridges. Eggs with large KCT’s only on one pole, but absent from elsewhere ( Figs. 36–41 View FIGURES 36 – 41 ). Micropyle close to polar cap.

Etymology. The genus name is an arbitrary combination of letter to honour Prof. Narumon Sangpradub (Khon Kaen University) for her outstanding contributions to the ecology and taxonomy of aquatic insects in Thailand. The gender is feminine.

Distribution. Thailand (Ratchaburi province, Chanthaburi province).

Discussion. Nymphal affinities. According to Kluge (2012), Sangpradubina clearly belong to Alatophlebomaxillata, Atalophlebolinguata and Choroterpes /fg1 by the following characters: 1) maxillae with one proximal comb-shaped dentiseta (distal dentiseta lost); 2) lingua with a pair of lateral processes arising near base and pointed distally; 3) shape of gills 1 different from gills II–VII.

Based on gill morphology, Sangpradubina is more closely related to the Thraulus group (sensu Grant & Peters 1993) than to other members of Choroterpes /fg1 ( Choroterpes Eaton 1881 , Euthraulus Barnard 1932 , Dilatognathus Kluge 2012, Monochoroterpes Kluge & Jacobus 2015). The Thraulus group currently encompasses seven genera, of which only three are known from the nymphal stage: Barba Grant & Peters 1993 , Nonnullidens Grant & Peters 1993 and Thraulus Eaton 1881 . The New Zealand genus Isothraulus Towns & Peters 1979 might also belong to the Thraulus lineage, but its phylogenetic position is not completely clear ( Towns & Peters 1996). In peculiar Isothraulus imaginal tarsi bear two hooked claws, while all Thraulus -related genera bear one hooked and one paddle-like claw.

Within the Thraulus group, the genus Thraulus is the most rich in species, with a total of 15 species described from the Palaearctic (3), Afrotropical (3) and Oriental (9) regions. The genera Barba and Nonnullidens , which encompass 7 species together, have been reported from Papua New Guinea, and recently Kluge (2013) proposed to consider Barba as a junior synonym of Nonnullidens . It is our opinion that this synonymy needs further investigation, because study of our extensive material from Papua New Guinea reveals that some nymphal characters could allow separating the two genera.

We compared the nymph of S. thailandica to those of several species of Thraulus , including Thraulus bellus Eaton, 1881 (type species of the genus), several unnamed species from Thailand, Borneo , Sumatra, Timor and Papua New Guinea, as well as several species of Barba and Nonnullidens from Papua New Guinea . Our new genus present unique characters among the Thraulus lineage, such as: 1) maxillae with few pectinate setae (ca. 11–13) in the subapical row and with well-developed anterolateral projection; 2) tarsal claws with 4 denticles at the base and 9 near the apex; 3) gill 1 comprised only of a single and slender lamella; 4) cerci and terminal filament bearing additional long, thin setae. The mandibles with only a tuft of setae in the middle of the lateral margin separate our new genus also from Barba and Nonnullidens . The nymph of Sangpradubina appears to be more closely allied with Barba and Nonnullidens than Thraulus , based on gill II–VII morphology, where the fimbriate part is located in the distal half (present on the whole margin in Thraulus ). Sangpradubina gill 1 clearly differs from those of the other three genera, with the notable exception of Thraulus femoratus Li, Liu & Zhou 2006 , from China, which also possesses a single and slender lamella, but in which all other characters clearly fit the genus Thraulus ( Li et al. 2006) . The first gill of most Thraulus species is comprised of long and slender dorsal and ventral lamellae, except for Thraulus gopalani Grant & Sivamarakrishnan, 1985 , from India, and T. torrentis Gillies, 1964 , from Tanzania, ( Peters et al. 1964) which have a dorsal lanceolate portion and a ventral fimbriate portion ( Peters & Tsui 1972; Grant & Sivaramakrishnan 1985).

Imaginal affinities. The genus Sangpradubina differs from other genera of the Thraulus group by the presence of 5 intercalary veins in the cubital field, whereas other genera possess only 2 intercalaries, including those for which nymphs remain unknown, such as Simothraulus Ulmer, 1939 , Sulu Grant & Peters, 1993 or Chiusanophlebia Uéno, 1969 . The shape of the hind wing also separates Sangpradubina easily from the enigmatic genus Magnilobus Grant & Peters, 1993 , which is known only from a female subimago from an island in the Bismarck Archipelago (northeast of New Guinea in the western Pacific Ocean). In the male imaginal stage, all other genera of the Thraulus lineage have penes lobes elongate, with the widest part generally at the apex (more rarely in the middle), whereas in Sangpradubina , the penes lobes are more stocky, with the widest part being at the base.

The puzzling thing is that the Sangpradubina male imago closely resembles those of Choroterpes s.l., especially with regards to venation of the cubital field of the wing, and general shape of male genitalia. When using the key provided in Peters & Edmunds (1970), Sangpradubina will key to Cryptopenella Gillies, 1951 , which is now considered as a subgenus of Choroterpes (Zhou 2006) , or even a synonym of the Choroterpes subgenus Euthraulus ( Kang & Yang 1994) . Our new genus however greatly differs from Cryptopenella species because, in the latter, the penes lobes are almost completely hidden under the styliger plate (Zhou 2006, Figs. 21–28 View FIGURES 19 – 22 View FIGURES 23 – 25 View FIGURES 26 – 31 ). Sangpradubina male adults also differ from those of Choroterpes s.s. and Euthraulus by the vein MP2 being independent of vein MP1, and the styliger plate margin being strongly convex. Kluge (2016) considers as an autapomorphy of Choroterpes /fg2 ( Choroterpes s.l.) the presence of what he calls a projection distal to the penes gonopore, and Sangpradubina also possesses this character ( Fig. 32 View FIGURES 32 – 35 ). Therefore, one could consider Sangpradubina as belonging to Choroterpes s.l. However, inclusion of this genus in Choroterpes /fg2 would destabilize the present concept of this monophyletic group by invalidating two of the three proposed apomorphies for the group, namely gill shape and egg papillae. Species placed in Choroterpes /fg2 never possess dense rows of setae on the outer margins of fore- and middle legs, which indicate that Sangpradubina may also be related to Indialis Peters & Edmunds, 1970 or Edmundsula Sivaramakrishnan, 1985 , two genera endemic to Southern India. Sangpradubina differs from these by the shape of the gills (each lamella lanceolate and not fringed as in the latter’s). In our opinion, Sangpradubina probably belongs to Choroterpes /fg 1 in Kluge’s (2016) scheme, and may have rank equal to Choroterpes /fg2, Indialis /g1, Thraulus /g1 and Nonnullidens /g1 ( Kluge 2016).

The egg chorionic structure of Sangpradubina also appears to be very peculiar. The general shape resembles that of many Thraulus species, being elongate with longitudinal ridges. They differ from those of Choroterpes s.l. by the absence of papillae connected by ridges, in the form of a flower-like protuberance ( Kluge 2012, Figs. 20– 24 View FIGURES 19 – 22 View FIGURES 23 – 25 ). The presence of large KCT’s on one pole is almost unheard of in the family Leptophlebiidae ( Koss & Edmunds 1974; Dominguez & Cuezzo 2002; Li et al. 2006), but this condition has been reported by Kluge (2012) for Choroterpes (Choroterpes) mercatorius from Sulawesi. We note that in C. mercatorius the papillae are present, contrary to the absence of such papillae on S. thailandica .