Marilia Müller

Oláh, János & Johanson, Kjell Arne, 2010, Description of 33 new species of Calamoceratidae, Molannidae, Odontoceridae and Philorheithridae (Trichoptera), with detailed presentation of their cephalic setal warts and grooves 2457, Zootaxa 2457 (1), pp. 1-128 : 73-75

Marilia Müller

Marilia Müller, 1880: 127 . Type species: Marilia major Müller (subsequent selection by Mosely & Kimmins 1953: 165). Type country: Brazil .

This is a widespread genus known from the Oriental, Australasian, Nearctic and Neotropical Regions. The male eyes are variously large, and there is a high degree of setal reduction in genitalic segments IX and X. The body of these segments is glabrous. The posterior spine row, and the dorsopleural or ventropleural setal surfaces are reduced on segment IX. The apicoventral and apicodorsal setose areas on segment X are weakly developed and represented only by few setae. Many species have similar male genitalia, and it is difficult to differentiate all species by examining the phallic apparatus alone. Flint (1983, 1991) and Bueno-Soria & Rojas-Ascencio (2004) found diagnostic differences in the suture pattern on segment IX in the Neotropical species, but this character seems less diverse among Oriental species. The cephalic setal wart pattern and genital characters are in combination important characters for separating species from this region. Important characters include (1) the shape of the lateroapical, roof-like, corner of tergum IX, (2) the groove pattern on segment IX, and (3) the longitudinal ridge pattern on segment X. A particular feature of the species in the genus Marilia is the large eye size, which resulted in specific modifications of the cephalic setal wart pattern. The dorsal setal wart pattern on the head is usually differently modified in different species, as is the facial setal wart pattern. Besides the cephalic groove and setal wart pattern, body colour and wing characters are also important for separating species. Table 1 summarizes distinguishing characters of the 8 Marilia species examined in this work. The characters used in the matrix are explained below.

General colour — This character represents appearances of a general body colour or a unique colour when present at particular body parts. For instance, “whitish” in M. tuyetmira means that this species has a white abdomen and setal warts, as well as whitish hyaline wings.

Foreleg tibia/tarsus colour — Four species out of the 8 species have dark foreleg tibia and tarsus.

Wing membrane pattern — All species examined have wing membrane without pattern except M. malickyi , new species that has light spotted forewing membrane and hind wings with anterior costal band. Other species, like M. tuyetmira , new species, may have dotted forewings due to presence of small groups of darker setae.

Forewing termen — Species with dark foreleg tibia/tarsus and smaller eye/wider vertex have concave termen.

Basal hind wing brush — Some species have hind wings with a long basal brush originating from the marginal surface of the small anal costal lobe, near the wing base. The setae are closely set and about equally long. Similar brushes occur in the Australian Marilia bola Mosely and Marilia aenigmata Neboiss , and the Neotropical Marilia crea Mosely and Marilia major Müller. The hind wing brushes of Phylloicus species ( Prather 2003) and Banyalarga species ( Prather 2004) arise from the dorsum of the third axillary sclerite, and are therefore not homolog with those of the costal lobe of the hind wings. The species that are examined for this work have various degrees of brush complexity, from absent to dense brushes enclosed in semi membranous sleeve.

Maxillary palp formula — There are differences among the examined species in the segmental ratio of the maxillary palp. In most species the first maxillary palp segment is the longest.

Interocular distance — The distance between the compound eyes on the vertex is probably determined by the size of the eyes. Eyes are mainly enlarged dorsally on vertex, and less in facial plane on the frons or clypeus. Intraspecific variation in the interocular distance has not previously been recorded, and observed variation in the interocular distance in the widespread Marilia malickyi , new species is therefore interesting.

Modified setal warts — The modification in size and shape of the vertexal setal warts is probably induced by the limiting space on the vertexal surface due to variation in eye size. The following shapes are observed: (1) compressed, longitudinally elongate; (2) small, rounded; (3) fused, with preserved vestigial septum, i.e. remnant of the rims on the fused part of the skeletal rings of 2 original warts; (4) complete fusion, with no rims of the skeletal rings.

Postoccipital setal lobe — A pair of triangular postoccipital setal lobes is present behind the occipital compact setal warts, in the deep triangular cleft or fissure, delineated by the postoccipital grooves. Similar setose lobes are observed in the genus Ganonema . Postoccipital setal lobes are also present in several Hydroptilidae groups, but these are possibly not homolog structures, and might have originated from the occipit ( Oláh & Johanson 2007). Postoccipital setal lobes are variously covered with setae, sense tubercles or sense pits.

Vertexal tubercle — A single pair of vertexal tubercle, sensory papillae or sensilla basiconicae is observed in genus Marilia . These sense tubercles, not previously studied in Trichoptera , are located along the posterior end of the coronal groove, between the occipital compact setal warts. The wall of these small peglike or conical tubercles, or short, rod-like processes, appears thick and strongly sclerotized. They have possibly tactile function.

Lateroapical corner on tergum IX — The sclerotized lateroapical region of tergum IX forms variously shaped plates overhanging the articulation of the preanal appendages. The shape of this area is an important diagnostic character for many Marilia species , and is present in all examined species, except M. enikiana , new species.

Groove pattern on segment IX — The true antecosta is the anterior submarginal, or marginal, ridge on the inner surface of segment IX. A strong ridge, or rim system, can include 3 components: (1) the primary intersegmental folds accompanied on the surface by the antecostal suture, i.e. the external groove of antecosta; (2) the dorsal and ventral longitudinal grooves attached to antecosta, and may represent seamed pleurotergal and pleurosternal lines; (3) the sclerotized sutures, or lines, on the posterior margins of segment IX, which might represent the vestigial antecosta and sutures of segment X. The skeletal reinforcement, or brace pattern, described by Flint (1983, 1991), is basically formed by similar components. In that system the anterior marginal or submarginal brace is the true antecosta; the dorsal and ventral brace represent the pleurotergal and pleurosternal lines; and the posterior marginal, or submarginal, brace on segment IX, is possibly the antecosta of segment X. Following this interpretation, the dorsal suture described by Bueno-Soria & Rojas-Ascencio (2004) being present on the apicodorsal margin of segment IX along the boundary of segments IX and X, is the dorsolateral marginal suture of segment IX. The suture appears to be common in Mexican and Central American species of this genus, although we have not detected it in any of the herein examined Oriental species.

Ridge pattern on segment X — Variously developed longitudinal ridges may be present on segment X. In Marilia species segment X is usually less sclerotized and the ridge system is less visible. A specific ridge pattern on segment X is found to be stable, and includes: (1) a single, or double, mesal longitudinal ridge running along dorsum from the basal area of segment X to apex, where it fuses or divides by the dorsal interlobular gap, as visible in dorsal view; (2) a pair of lateral, longitudinal ridges may be present along the marginal ridge of the apicolateral depressions; (3) the marginal ridge of the depression or concavity usually forms an oblique, dark line running from anterodorsal to posteroventral part of segment, as seen in lateral view.

Coxopodites — The size, shape and setal cover of the coxopodites are important diagnostic characters. Variation in the examination plane can erroneously indicate different forms, and making comparison of species unreliable.