Diplectrona marginata ( Betten 1909 )

Pandher, Manpreet Singh, Kaur, Simarjit, Garima, Deepti & Parey, Sajad H., 2021, Genus Diplectrona Westwood 1840 (Insecta: Trichoptera) in India, Zootaxa 5047 (3), pp. 342-352 : 345-349

Diplectrona marginata ( Betten 1909)

( Figs 6–20 )

Hydromanicus marginatus Betten 1909: 236–237 , plate 15 fig. 13; syntypes 2 females: Kurseong [West Bengal], Annandale , May 1906; deposited in the Indian Museum [NZC], Kolkata, India.

Diplectrona marginata ( Betten 1909) ; Martynov (1935: 181–182, text figs 83, 84a–84c), new combination, male described; Gosh & Chaudhury (1998), reported from India (Himachal Pradesh, Uttar Pradesh, West Bengal); Malicky (2002), discussed identification problems.

D. kinulta Oláh et al. 2020: 160–161 , figs 23–27; holotype male: China, Tibet, Muotuo [county], 80K 1000 m, 24.vii.2012, leg. Li Wen-liahng; deposited in the Entomological Museum of China Agricultural University, Beijing; NEW SYNONYM.

Neotype. We designate a neotype for D. marginata ( Betten 1909) . One of the 2 female syntypes from India [Kurseong, West Bengal, collected by Dr Nelson Annandale, in May 1906] is missing from the NZC and is probably destroyed. The senior author himself examined the remaining one of these syntypes which is in very bad condition without head and with damaged wings, although the abdomen is intact. Another set of specimens from the Indian Himalayas ( Martynov 1935: 181) was assigned to D. marginata and a male was described by Martynov (1935). The original description of the species is ambiguous and incomplete, creating confusion and uncertainty about the identity of this species and its distinction from other species ( Schmid 1961: 201; Malicky 2002: 1214). Females of this genus are very similar and diagnostic characters for distinguishing them are subtle or unknown ( Ito & Nozaki 2018; Mey 1999; Neboiss 2002; Wells & Neboiss 2018). Therefore, although Malicky (2002) recommended that the name Diplectrona marginata should be treated as a nomen dubium, we prefer to select a neotype from among a series of specimens in the Indian Himalayas ( Martynov 1935: 181–182) and conforming with the limited details of the original description, thereby “clarifying the taxonomic status” of the species (International Code of Zoological Nomenclature 1999, Article 75.1). The specimen selected here is said by Martynov (1935) to “represent a mountain form of the species.”

Material examined: Neotype: Male. India: Collection Label Verbatim: Punjab, Ghuma , Simla Hills , 3760 ft., 6–8-ix-1925, B. Chopra; Interpretive data: Himachal Pradesh, Shimla Hills, Gumma Village ( Ghuma of Martynov ), 1520 m, 6–8-ix-1925, B. Chopra ( NZC).

Additional Material: Himachal Pradesh, Shimla Hills, Gumma Village ( Ghuma of Martynov ), 1520 m (as per interpretive data), 6–8-ix-1925, Chopra, ( NZC), 4 males . Uttarakhand, Dehradun, Jhabarkhet (on Mussoorie-Tehri Road ), 1300 m, 20–25-vi-1930, Chopra, ( NZC), 1 male, 1 female (damaged) . Mandal , 1700 m, 14-vi-2009, Pandher & Parey, ( NPC), 1 male, 1 female . West Bengal, Kurseong , 1500 m, 17-vi-1910, Annandale, ( NZC), 1 male, 1 female ; Darjeeling , 2000 m, (no date is mentioned on label), Lynch, ( NZC), 1 female .

Diagnosis. The male genitalia of D. marginata , in the shape of the lateral lobes of tergum X, are similar to D. jacobsoni Malicky and Chantaramongkol 2002 and D. pachalatkoi Malicky 2009 . However, the mesocaudal lobes of tergum X are fused half their length, slender basally, broad apically, mesoapically pointed, narrowly separated apically in dorsal view in D. marginata ; whereas the mesocaudal lobes of tergum X are broad at their base and separated apically in D. jacobsoni and the mesocaudal lobes of tergum X are fused, broad at their base and rounded apically with a narrow mesal separation in D. pacholatkoi . Furthermore, in D. marginata , the lateral lobes of tergum X are more divergent than in those species and a small inner lobe-like structure (or fold) is visible on the mesal margins of the lateral lobes of tergum X in dorsal and lateral views in D. marginata , a unique characteristic for this species. Drawings of genitalia of three other specimens are provided to show variation. These were redrawn to show the variation in the lateral lobes of tergum X which might be seen on opposing lateral lobes even in genitalia of the same specimen. For example, Fig. 19 generally agrees with fig. 24 of Oláh et al. (2020) in dorsal view. These are shown to justify our conclusion that this species is widely distributed with local variation and complexity or adaptive traits based on morphology.

Redescription of adult male. Color in alcohol light brown, maxillary palp infuscate, legs and antennae pale yellow, dorsum of head dark brown, no setae or hairs visible on eyes. Length from tip of head to apices of folded forewings about 7.25 mm; maxillary palps each about 1.75 mm long, segment V longest; labial palps small, each 0.50 mm long. Length of each forewing about 6 mm; venation typical for genus; discoidal cell small; forks II and III petiolate, Cu 2 and A curved. Hind wings each 5.25 mm long, broad; Sc very thick; R1 fine and sinuate, fork I present. Gland on V sternum visible, filament directed posterad, length of filament more than 1.5x but less than 2x sternite length.

Male genitalia ( Figs 6–20 ). Abdominal segment IX annular; anterolateral margins convex, angled at anterior ends of pair of internal longitudinal carinae above middle; posterior margins irregular, produced slightly over bases of inferior appendages. Tergum X divided into pairs of mesocaudal lobes and lateral lobes; mesocaudal lobes fused, apically separated for short distance, blunt apicomesally, longer than lateral lobes; lateral lobes covered basally by broad and setose preanal appendages, broad basally and divergent with distal margins curved laterad, pointed, each with small sclertotized fold on mesal surface. Preanal appendages paired, broad, with prominent large setae visible both in lateral and dorsal views. Inferior appendages each 2-segmented; basal segment long, extending beyond mesocaudal lobes of tergum X, broad basally and apically in lateral view, slightly constricted and with slight bend dorsad near base, in ventral view abruptly curved mesad preapically; apical segment broad at base, 1/3 as long as basal segment in lateral view, curved mesad in ventral view and sharp apically. Phallus, tubular, slightly angled ventrad near base, with one pair of elongate spines and ventral scoop-like structure apically; phallicata complex and with pair of long, semicircular sclerotized ventral lobes in ventral view.

Recently, Oláh et al. 2020 described D. kinulta from Tibet, mentioning in the diagnosis that this species is similar to D. burha because both of these species have subquadrangular, plate-like paraprocts (lateral lobes of tergum X) with variously divergent apical patterns. They did not mention D. marginata but observed that the male of D. kinulta differs from that of D. burha by the character combination of small seta-less eyes, a pair of large internal sacs in segment VIII, long posteroventral filaments on sternite V (2.24 times as long as the sternite), fork I on the hind wings, elongate lobes of segment X; and a deltoid head of the phallic organ. In contrast, the male of D. burha is characterized by lateral filaments of segment V that are 1–2 times as long as the segment, small internal glands of segment V, absence of internal glands of segment VIII, and a different shape of the genitalia ( Malicky 2002; Ito & Nozaki 2018: 547, figs 2A, 2B). The male genitalia of D. burha are distinguished from those of other congeneric species (including D. marginata ) mainly by large preanal appendages (p.a.) and segment X having each subquadrate lateral lobe often with a depression in the apical margin in dorsal aspect and its well-developed mesocaudal lobes (m.c.l.) are separated by a narrow mesal slit in dorsal aspect ( Malicky 2002: pl. 14; Ito & Nozaki 2018: 547, fig. 2C).

According to Oláh et al. (2017, 2020), the paraprocts are an extremely stable and invariant organ in a species but differing among species, including those in Diplectrona . Paraprocts act as titillating or stimulating organs of the genitalia, typically formed by an adaptive mechanism, and are a stable genetic component compared to the variable neutral organs under the influence of stochastic events. They (2020) conclude that Diplectrona is very diverse in southern Asia, with several species complexes currently identified as a single species, complexes they purport to be best analyzed with “fine phenomics.” The remaining questions and the validity of their research program, of course, can be addressed in future research based on population samples, molecular studies, and more care with a research focus on adaptive speciation traits. In the meantime, based on the observed morphological similarity, we consider D. kinulta a synonym of D. marginata .

Distribution. India (West Bengal, Himachal Pradesh, Uttarakhand), China (Tibet).

Figures

FIGURES 6–10. Diplectrona marginata (Betten 1909) neotype from Ghuma (Shimla) (Himachal Pradesh, India), male genitalia. 6, left lateral; 7, dorsal; 8, right inferior appendage, ventral; 9, phallus, left lateral; 10, phallus, ventral.

FIGURES 11–15. Diplectrona marginata (Betten 1909) from Mandal (Uttarakhand, India), male genitalia. 11, left lateral; 12, dorsal; 13, right inferior appendage, ventral; 14, phallus, left lateral; 15, phallus, ventral.

FIGURES 16–20. Diplectrona marginata (Betten 1909), male genitalia. 16, 17, specimen from Jhabarkhet (Uttarakhand, India): 16, left lateral; 17, dorsal. 18, “D. burha” from Chiangmai (Thailand), male genitalia, left lateral (redrawn from Malicky 2002). 19, “D. sanguana” from Trisuli River, Kurlinghat, (Nepal), male genitalia, dorsal, showing tergum X variation (redrawn from Malicky 2002). 20, “D. sanguana” from Kurlinghat (Nepal), male genitalia, dorsal, showing tergum X variation (redrawn from Malicky 2002).