Xiphocentron (Antillotrichia) sclerothrix, Pes, Ana Maria, Hamada, Neusa, Nessimian, Jorge Luiz & Soares, Climéia C., 2013

Pes, Ana Maria, Hamada, Neusa, Nessimian, Jorge Luiz & Soares, Climéia C., 2013, Two new species of Xiphocentronidae (Trichoptera) and their bionomics in Central Amazonia, Brazil, Zootaxa 3636 (4), pp. 561-574 : 568-573

Xiphocentron (Antillotrichia) sclerothrix sp. nov. Pes & Hamada

Figs. 17–27

Etymology: The name sclerothrix refers to the long rough setae on the internal margins of the preanal appendages, where sclero (Greek) = hard, thrix (Greek) = hair.

Adult. Mean length of each forewing of male 2.84 mm (SD = 0.50 mm, n = 4 males), of female 2.83 mm (SD = 0.24 mm, n = 6 females). Head and body black (non-teneral specimens soon after emergence) or brown (in alcohol), forewings covered with uniformly fine and long brown setae ( Fig. 17 ). Forewings each with forks 2 and 4 ( Fig. 18 ), hind wings each with fork 2 ( Fig. 19 ). Apical spur of each hind tibia of male about 1.2 times as long as basal tarsal segment. Male with pair of digitiform glandular processes laterally on abdominal sternum V, with length about 1/3rd as wide as segment; opening of each glandular process located subapically ( Fig. 20 ); in females, glandular processes smaller, 1/3rd as long as processes of male, mammiform ( Fig. 21 ). Male abdominal segments VII and VIII densely setose.

Male genitalia. Tergum IX in lateral view elbow-shaped, tapered to blunt apex ( Fig. 22 a); in dorsal view anterior margin with mesal, U-shaped emargination, posterior margin rounded with slight incision ( Fig. 24 ). Sternum IX in lateral view subrectangular, about 2 times as long as high, posterolateral/dorsal and ventral margins straight, with slender and slightly curved anterolateral process on each side ( Fig. 22 a); in ventral view subtriangular, widest posteriorly, with nearly straight posterior margin, half as wide anteriorly, with rectilinear excision ( Fig. 23 ). Tergum X semi-membranous, in lateral view subrectangular, with dorsal margin straight, posterodorsal apex convex, posterior apex inflated, sinuous, and ventral margin concave ( Fig. 22 b); in dorsal view long and narrow, constricted at 2/3rds length, apically inflated ( Fig 24 ). Preanal appendages long, covered with numerous long bristles, sinuous in lateral view, dilated apically in dorsal view. Inferior appendages subequal in length with preanal appendages, in dorsal view internal margin of each appendage with two dense brushes of dark sclerotized setae, one small brush on proximal region with about 11 setae and larger one medioposteriorly with about 25 setae, followed by irregular row of finer setae to apex ( Fig. 24 ). Phallus long, very slender, tubular, with subapical reticulation and enlarged apex ( Fig. 25 ).

Female genitalia. Segments VIII and IX narrow, truncate apically. Segment X tubular, slender, subequal in length with segments VIII and IX combined, apical region with pair of oval lobes each with slender process on apex.

Pupa. Mean length 3.28 mm (SD = 0.50 mm, n = 6). Head with one pair of setae on vertex, three pairs of frontal setae, two setae laterally beside each eye and two setae lateral on each antennal scape; labrum subtriangular, with three pairs of long basolateral setae; mandibles triangular, each with apical half darker, prominent, with serrated mesal margin ( Fig. 26 ); antennae as long as body. Middle legs each with tarsus depressed and wide ( Fig. 28 ). Abdomen long, broad and stout; in dorsal view most segments rectangular in shape; terga I–VII with one pair of setae; pair of anterior hook plates (2a–7a) on each of terga II–VII directed backward and curved downward, posteriorly broad and short with 8–11 strong and sharp teeth of irregular length (except 6a long and narrow with 8 teeth, 7a curved upward with 9 short and strong teeth); pair of posterior hook plates (5p) on tergum V directed backward and curved downward, long and narrow with 10 teeth ( Fig. 29 ); segment VIII slender, without setae; segment IX small, slender and elongate. Male abdominal apex with pair of small, rounded, mesal lobes and one pair of elongate lateral lobes, each bearing 4 dark, long apical setae; abdominal apex of female with small rounded lobules.

Pupal retreat. Mean length 4.99 mm (SD = 0.04 mm, n = 3). Constructed of fine sediment, silk and sand, attached to substrate, usually in depressions of rock, frequently found outside of water.

Diagnosis: Xiphocentron sclerothrix sp. nov. belongs to subgenus X. (Antillotrichia) because the male has a spiniform sclerite on the internal margin of each inferior appendage. The male of X. sclerothrix sp. nov. differs from the male of X. haitiense by having the ventral glandular process of abdominal segment V digitiform; X. haitiense , the only other species of X. (Antillotrichia) for which this structure has been described, has this process on a scale-shaped region (Djernaes, 2011). The new species differs from the other species of X. (Antillotrichia) by having, in dorsal view, the internal margin of the inferior appendages each with two dense brushes of dark setae and preanal appendages with the apical region inflated. In the other species of Xiphocentron (Antillotrichia) the preanal appendages are straight such as in X. moncho , X. nesidium Flint 1968 , X. parentum Botosaneanu, 1988 and X. haitiense or have pointed apices as in X. borinquensis Flint, 1964 .The female of X. sclerothrix sp. nov. has the typical characteristics of the family, but there are no diagnostic characters by which to distinguish it from those of X. moncho and X. haitiense , which are the only species for which the females have been described and illustrated.

The pupa of X. sclerothrix sp. nov. differs from those of X. haitiense and X. moncho mainly by having the 5p hook plates concave, long and narrow, with 10 teeth; in X. moncho and X. haitiense the 5p hook plates each bear 5 teeth. The new species also differs in hook plates 5a, in which the teeth are distributed as a continuous line, while in X. haitiense there are 8 teeth, 4 on each side with a median interval and in X. moncho there are only 8 teeth; each hook plate 6a is similar to that of X. moncho and differs from that of X. haitiense which has only 4 teeth; the expanded tarsi of the middle legs are similar to those of X. haitiense , but differs from those of X. moncho in which the tarsi are not expanded.

Material examined. Holotype, male: BRAZIL, Amazonas, Presidente Figueiredo, “igarapé da Caverna do Maroagoa, km 6 AM 240”, 01º04’20.33"S / 059º58’54.24"W, 04.viii.–04.ix.2008, A.M.O. Pes; J.O. da Silva, A.P. dos Santos (legs.): 1 male [pinned] and exuviae [glycerine], (INPA).

Paratypes: BRAZIL, Amazonas: Presidente Figueiredo: “ramal do Castanhal, igarapé Canoas”; 011º49'51"S / 0601º04'15"W, 03–10.i.2001, A.M.O. Pes (leg.), 1 male (pinned, 135, INPA); same collection data except 03–12. i.2001, 1 male (pinned, 136, INPA); same except 03–22. i.2001, 1 male (pinned, 137, INPA); same except 04-viii–03.ix.2008, A.M.O. Pes; J.O. da Silva, A.P. dos Santos (legs.), 1 male (pinned, 138, INPA); same except 03.i.–27. ii.2001, 1 male (alcohol, 139, INPA); same except 04–18.viii.2008, A.M.O. Pes; J.O. da Silva, A.P. dos Santos (legs.), 1 male (alcohol, 140, MZUSP); same except 04.viii.–09. ix.2008, 1 male and exuviae (alcohol, 142, INPA); same except 30.ix.2000, A.M.O. Pes; J.O. da Silva, 1 female (alcohol, 143, INPA); same except 04–22. viii.2008, 1 female (alcohol, 144, INPA); same except 04–25. viii.2008, 1 female and exuviae (alcohol, 145, MZUSP); same except 04.viii.–10. ix.2008, 1 female (alcohol, 146, INPA); same excpet 04.viii.–12. ix.2008, 1 female (alcohol, 147, INPA); same except 04.viii.–17. ix.2008, 1 female and exuviae (alcohol, 148, INPA); “km 60 AM 240, igarapé de 1ª ordem na caverna”; 01º59'32.7'S / 059º31'20.1"W., 22–24.ii.2007, A.M.O. Pes (leg.), 1 male and exuviae, 1 female (alcohol, 149-150, INPA); same except 22.ii.–08. iii.2007, 1 female and exuviae (alcohol, 151, INPA); same except 22.ii.–12. iv.2007, 1 male (alcohol, 152, INPA); same except 22.ii.–20. iv.2007, 1 male and exuviae (alcohol, 153, INPA); same except 22.ii.–23. iv.2007, 1 female and exuviae (alcohol, 154, INPA); “igarapé da Caverna do Maroagoa, km 6 AM 240”; 01º04’20.33"S / 059º58’54.24"W, same except 04.viii.–27.x.2008, A.M.O. Pes, J.O. da Silva, A.P. dos Santos (legs.), 1 male and exuviae (alcohol, 155, INPA); “Cachoeira da Onça”, 02º02'08.1"S / 060º02'02.8"W, 05.viii.2008, A.M.O. Pes, J.O. da Silva, A.P. dos Santos (legs.), 1 male (alcohol, 156, INPA); Barcelos: “base da Serra do Aracá, igarapé do Jabuti”, 00º52'34,21"N / 063º28'27,05"W, 125 m alt. 25.vii.–04.viii.2009, Malaise trap, A.P. dos Santos, N. Ferreira-Jr. (legs.), 1 male and 4 females (alcohol,(157-161, INPA); Amapá, Oiapoque: “igarapé no Aeroporto FAB, (#12 AP), 08.viii.–07.ix.2011, A.M.O. Pes, P. Cruz, A. Fernandes, N. Hamada (legs.), 1 male (alcohol, 162, INPA).

Additional material examined. BRAZIL, Amazonas, Presidente Figueiredo: Ramal do Castanhal, igarapé Canoas”; 01º49'51"S / 060º04'15"W, 30.ix.2000, A.M.O. Pes, J.O. da Silva, J. Bosco, 1 pupa (pharate male) (alcohol, 163, INPA); Cachoeira da Onça”, 02º02'08.1"S / 060º02'02.8"W, 05.viii.2008, A.M.O. Pes, J.O. da Silva, A.P. dos Santos (legs.), 2 pupae (pharate males), 1 pupa (pharate female) (alcohol, 164–166, INPA).

Bionomics. Larvae and pupae of Machairocentron and Xiphocentron were collected in bedrock streams, in lotic and lentic environments and outside of the water, in shaded humid areas on stream banks (e. g., walls of caves, stream banks covered with leaf litter and mosses). Larvae of the two species are indistinguishable morphologically and ecologically and they were common in streams located in Presidente Figueiredo and Manaus municipalities. Larvae and pupae used sedimentary rocks, submerged trees and branches and the roots of plants as substrate, usually located in the splash zones of waterfalls.

Since no morphological differences were observed between the two species collected in the region, the food habitat characterization presented below can be attributed to both species.

The larval guts contained fine sediment, plant cells, invertebrate cuticle, chlorphytes, cyanophytes and diatoms ( Table 1). Sediment was predominant in the stomach contents because larvae scrape the substrate to obtain their food; this fact was already observed by Wiggins (1996) who reported Xiphocentronidae larvae feeding on microalgae and debris associated with the substrate surface.

Xiphocentron adults were only collected in the Canoas stream while in the other three streams (Onça and Sr. José streams, in Presidente Figueiredo municipality; Acará stream, in the Reserva Ducke, Manaus municipality) only Machairocentron adults were collected. However, since the sites are very close to each other, especially the ones in Presidente Figueiredo municipality, it is not possible to exclude the possibility that the distributions of the two species can overlap.

Diatomaceae (Crysophyta: Bacillariophyta) Cymbella sp.

Eunotia subrobusta Hustedt Eunotia bidentula W. Smith Eunotia flexuosa (Brbisson) Kützing Eunotia spp.

Frustulia rhomboides (Ehremberg) De Toni Gomphonema sp.

Navicula sp.

Pinnularia sp.

Surirella sp.

Chlorophyta Actinastrum sp.

Actinotaenium obcuneatum (W. West) Teiling Actinotaenium palangula (Brbisson) Teiling Ankistrodesmus sp.

Cosmarium contractum Kirchner , Cosmarium quadratulum (Gay) De Toni Cosmarium sp.

Eunastrum sp.

Oendogonium sp.

Cyanophyta Chorococcus sp.

Hapalosiphon sp.

Figures

FIGURES 17 – 21. Adult of Xiphocentron (Antillotrichia) sclerothrix sp. nov.. 17) male habitus, dorsal view; 18) right anterior and 19) posterior wings, dorsal views; 20) male abdominal sternum V (arrow indicating left process), ventral view; 21) female abdominal sternum V (arrow indicating right process), ventral view.

FIGURES 22 – 25. Adult male of Xiphocentron (Antillotrichia) sclerothrix sp. nov. 22 a) genitalia, left lateral view; 22 b) phallus, left lateral view; 23) sternum IX, ventral view; 24) genitalia, dorsal view; 25) phallus, left dorsolateral view.

FIGURES 26 – 29. Male pupa of Xiphocentron (Antillotrichia) sclerothrix sp. nov. 26) Mandibles and labrum, dorsal view; 27) left half of abdominal segments IX – X, ventral and dorsal views; 28) left tibia and tarsus of middle leg, posterior view; 29) right hook plates (2 – 7 = abdominal segment number, a = anterior, p = posterior), dorsal view.