Chimarra Stephens

Cartwright, David, 2020, A review of the New Guinea species of Chimarra Stephens (Trichoptera: Philopotamidae), Memoirs of Museum Victoria 79, pp. 1-49 : 5

Chimarra Stephens

Type species. Chimarra marginata by monotypy.

General features of males of New Guinea Chimarra

No formal key is provided for several reasons – primarily because many characters varied considerably between species (e.g. Rs sinuous or curved, thickened ranging to straight and not thickened basad of discoidal cell in forewing, ventral process on segment IX ranged from elongate and pole-like to absent). Because of the poor condition of many of the specimens (including the wings) and at times inadequate clearing of the genitalia, some features were difficult to discern with confidence.

Species are progressively separated throughout this paper on the basis of the L/W ratio of the ventral process on segment IX. Species were identified secondly by small differences in the shape of the inferior appendages (especially in lateral view) and the shape and position of the pair of lateral lobes on segment X.

The first feature used was the ventral process on segment IX. The relative length and the L/W ratio are used as a basic means of separating the New Guinea Chimarra species. The L/W ratio varies from 20 in C. pertica to 0 (absent) in many species. Having a similar ratio does not necessarily imply a relationship between the species. Only a few species (mostly from the C. papuana group) such as C. pertica , C. guentheri and C. ukarumpana have an elongate and slender ventral process. Most species have a triangular or rounded keel or no obvious process. In the region, most Australian species have no obvious keel or only a small triangular one ( Cartwright, 2002). Of the nearby Solomon Islands species, most have no obvious keel but Chimarra talinensis Johanson and Espeland has an elongate and robust ventral process ( Johanson and Espeland, 2010), while in 24 species from Fiji ( Johanson and Oláh, 2012) and three species from Vanuatu ( Johanson et al., 2011), none has an obvious ventral process. Of the south-east Asian species, most have no obvious process or only a small keel; a few have a more pointed and elongate process, including C. chiangmaiensis Chantaramongkol and Malicky , C. khamuorum Chantaramongkol and Malicky , C. demeter Malicky ( Malicky, 2010) . In Borneo, species in East Kalimantan ( Indonesia) and Sabah ( Malaysia) have elongate ventral processes, including Chimarra devogeli Blahnik et al. , C. drepane Blahnik et al. , C. fuilianae Blahnik et al. and C. xiphosella Blahnik et al. ( Blahnik et al., 2009) .

The second character used here for species separation is the shape of the inferior appendages (predominantly as viewed laterally). The worldwide range of variation in this structure is remarkable among Chimarra species. Although most New Guinea species have distinctively shaped inferior appendages, several exhibit slight variations on a pattern of otherwise almost uniformly elongate sub-triangular inferior appendages (in lateral view), making it difficult to distinguish them from each other using this character. Many of the species have inferior appendages with acute apices that are inflexed or directed posteromesally and so are hidden in the lateral view; instead, these appendages may appear slightly truncate or abbreviated.

Other characteristics of interest include the form of the lateral lobes of segment X, the shape of preanal appendages on segment IX, the variety and shape of phallic structures, the presence or absence of obvious sensilla on the lateral processes of segment X, and variations in wing venation.

General characteristics of the New Guinea Chimarra . General body colour and wings brownish (unless faded with time in alcohol). Spur formula 1:4:4. Small to medium-sized adults. Forewing length range, males: 3.5– 7 mm, more commonly 4–6 mm. Forewing often with Rs sinuous or curved, thickened (sometimes straight and not thickened) basad of discoidal cell, occasionally with small, clear, depressed window (fig. 63), forks 1, 2, 3 and 5 present; hind wing with forks 1 (usually), 2, 3 and 5 present (fig. 7). At least two species – C. cyclopica and C. aliceae – appear to have fork 1 absent on the hind wing, as originally noted by Kimmins for C. cyclopica ( Kimmins 1962) .

Male. Segment IX anterior margin ventral basally usually welldeveloped, often rounded or V-shaped; ventral process usually present, rarely very long (figs 1, 4), more usually short, keel-like (figs 70, 78, 132) or without obvious process (figs 155, 158). Preanal appendages usually short, rounded. Segment X with mesal lobe membranous, reduced and pair of more heavily sclerotised lateral lobes, mostly adpressed to phallus and without short hair-like sensilla discerned. Phallus generally tubular, phallobase expanded, rounded, usually with a pair of short, slender, straight or slightly curved spines included subapically, more rarely with only one or without obvious spines. Inferior appendages one-segmented, shape highly variable.

Female. Females have rarely been associated for any New Guinea species and were not examined during this study.

Remarks. No new material was seen for most of the previously described New Guinea species. During this study, new material was examined for the following nine species: C. aiyura , C. biramosa , C. cyclopica , C. falcata , C. goroca , C. kokodana , C. sedlaceki , C. sinuosa and C. ulmeri . These are re-described and significant parts are figured here.

A papuana species group comprising eight species – C. agasa Oláh , C. bobita Oláh , C. kalija Oláh , C. kozela Oláh and Mey , C. papuana Kimmins , C. porsen Oláh , C. tompa Oláh and C. tulok Oláh – was recognised by Mey (2006) and further refined by Oláh (2014). In this study, four new species ( C. bintang sp. nov., C. mendiana sp. nov., C. milneana sp. nov. and C. ukarumpana sp. nov.) are aligned with the group, primarily on the basis of the unique characteristic of the long and curved filiform dorsoapical process on the inferior appendages, supported by the generally elongate ventral process on segment IX. Due to the poor condition of many of the dried BPBM specimens examined during this study, it is not possible to check and confirm all of the group characters, especially some characters discussed by Mey (2006) and Oláh (2014). No clear groupings were discerned among most of the New Guinea species; therefore, none of the species below are formally or informally grouped.