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1 2 NICO NIESER & MONICA LOPEZ RUF 1Tiel, The Netherlands 2Museo de La Plata, Argentina A REVIEW OF LIMNOCORIS STÅL (HETEROPTERA: NAUCORIDAE) IN SOUTHERN SOUTH AMERICA EAST OF THE ANDES Nieser, N. & M. Lopez-Ruf, 2001. A review of Limnocoris Stål (Heteroptera: Naucoridae) in southern South America east of the Andes. – Tijdschrift voor Entomologie 144: 261-328, figs. 1- 202. [ISSN 0040-7496]. Published 1 December 2001. Revision of the species the genus Limnocoris Stål occurring in the area Southeast Bolivia, South- east and South Brazil, Paraguay, Uruguay and Argentina with a key to the species occurring in this area. Ten new species are described: L. asper, L. caraceae, L. decarloi, L. espinolai, L. inter- medius, L. lanemeloi, L. machrisi, L. porphyros, L. saphis and L. subpauper all from southern Brazil. Lectotypes are designated for four species: L. maculiceps Mont., L. ovatulus Mont., L. pectoralis Mont. and L. pusillus Mont. The following synonymies are established, junior synonyms between brackets: L. borellii Mont. [L. manco-capasi Poiss., L. stali Mont.]; L. burmeisteri De C. [L. bachmanni De C.]; L. insignis Stål [ L. uhleri Mont., L. admontandoni La R.] L. nigropunctatus Mont. [L. sattleri La R.]; L. pauper Mont. [L. plaumanni La R.]; L. pusillus Mont. [L. mansosotoi De C., L. vianai De C.]. A checklist for the entire genus Limnocoris, with synonymies and location of holotypes has been added. Dr. N. Nieser, Htg. Eduardstr. 16, 4001 RG, Tiel, The Netherlands. E-mail: iftang.01@ net.HCC.nl Key words. – Naucoridae, Limnocoris, new species, new synonymies, lectotypes, Argentina, S. Brazil, key, checklist. Spanish and Portuguese summaries on page 328. Within the infraorder Nepomorpha (true aquatic simple experiment with Limnocoris maculiceps Mon- bugs), the family Naucoridae contains the largest tandon showed that they can stay submerged for a number of taxa which are adapted to living in run- week or more (Nieser & Lane de Melo 1997), which ning waters. Many of these are benthic and unable to suggests that this genus might have plastron respira- fly. The majority of benthic species prefer small tion too. However, so far no morphological study has streams where they regularly appear to be (one of) the been made to verify the existence of a plastron. species at the top of the food chain in the benthic mi- In South America the predominant genus of benthic crohabitat (Sites & Willig 1991). Thus, they are not Naucoridae is Limnocoris Stål (1860) which constitutes only interesting for entomologists, but also for ecolo- the monotypic subfamily Limnocorinae. An interest- gists and environmentalists for evaluation of ecologi- ing second is Cryphocricos Signoret (1850) the type cal conditions in streams. genus of the subfamily Cryphocricinae, which has The main adaptation of these forms is the develop- some species living in conditions of very strong cur- ment of efficient respiration which enables them to rent, whereas several of the South American species of stay permanently submerged. This type of respiration Ambrysus Stål (1862) the largest genus of the was most intensively studied in the related family Cryphocricinae, which are also inhabitants of streams, Aphelocheiridae (Thorpe & Crisp 1947). They are not really benthic (La Rivers & Nieser 1972). found a very dense layer of very short and fine hairs, Species of Ambrysus occur mainly in Mexico and the called a plastron, which ensures a permanent film of Southwest of the U.S.A. (La Rivers 1971). The Am- gas on the ventral side and large parts of the dorsal brysini (Cryphocricinae) of the area under considera- side. In this thin layer gas exchange takes place. A tion are treated by Nieser et al. (1999). Cryphocricos 261 Downloaded from Brill.com10/07/2021 10:35:42PM via free access T E, 144, 2001 has been revised by Usinger (1947) and the Argen- type is indicated as being the larger or smaller speci- tinean species by Lopez Ruf (1991). Both subfamilies men. Length and width without specification refer to are restricted to the Americas. Taking into account the the maximum values of body length and width. proposed synonymies and descriptions of new species Larvae. – With larvae V, only the mean of mea- proposed in this paper, Limnocoris contains 71 species surements of five specimens (if available) is given. mainly occurring in South America and seems to be Mature instar V larvae can be kept quite well in dry especially richly represented in Southeast Brazil and condition glued on a card but the measurements of North Argentina although this may be partly due to various dimensions will be slightly lower in dry speci- higher intensity of collecting. The fauna of the Andes mens compared to alcohol specimens. is probably quite rich too (Nieser et al. 1993, Sites in Head. – The head may be at an angle with the rest of litt.) but consists mainly of different species. A few the body. Measurements of the head were taken with species such as L. borelli and L. pectoralis have a wide the longitudinal axis of the head in a horizontal plane, distribution in the eastern foothills of the Andes. The which might, in some species, result in a different val- fauna of the Amazon Region and the Guyanas is com- ue of the length of the head when it is measured with paratively poorer and has been summarized by Nieser the main longitudinal body axis in a horizontal plane. (1975). De Carlo (1951) summarized the species of However, the combined length of head+pronotum was the southern part of South America essentially on the taken with the main longitudinal body axis horizontal base of the collections of Museo Argentino de Cien- so this measurement usually differs from the sum of the cias Naturales. He overlooked a few species and a fair separate measurements of length of head and prono- number have been described in subsequent publica- tum. Length of an eye is measured along its inner mar- tions. As the senior author encountered a number of gin again with the axis of the head horizontal (fig. 3, new species and identification problems while study- le). The width of an eye is measured perpendicular to ing the fauna of Minas Gerais and since the second au- the inner margin of the eye (fig. 3, we). thor has been studying Naucoridae of Argentina for Legs. – Length and width of anterior femur are many years, we decided to join efforts and sort out the measured according to fig. 4. The length of meso- taxonomy of the genus Limnocoris in the area from the and meta-tibia is without the terminal comb of Brazilian states of Espírito Santo, Minas Gerais, Goiás spines. and Mato Grosso south to Argentina. The choice of In a few cases measurements are estimates based on area is somewhat artificial but there was no material a single damaged specimen, such estimates are pre- from Northeast Brazil and Bahia available, the Ama- sented between < >. zon-basin with the Guyanas has apparently a different fauna (De Carlo 1967, Nieser 1975). Drawings Drawings were mostly made with a camera lucida on a stereo microscope, the pseudoparameres were in MATERIAL AND METHODS many cases made from temporary microscopic slides. Material Because the general form of the legs gave no clues to Studies in this genus were prompted by fresh mater- specific identification, they usually were omitted in ial collected in Minas Gerais in connection with the the drawings of the general habitus. preparation of a guide to the water bugs of Minas Gerais and a box of specimens from Brazil obtained Synonymy from F. Plaumann, Nova Teutonia, Santa Catarina, The catalogue of the Naucoridae by La Rivers Brazil. Soon it became clear that a revision of the genus (1971, 1974, 1976) contains extensive synonymies for the southern part of South America was needed. and references. So in this paper only essential syn- onymies are given. In addition references published af- Measurements ter the catalogue by La Rivers have been incorporated. General. – Measurements are in mm, when suffi- cient material is available, based on five specimens of Terminology each sex. In case of descriptions of new species the spec- The anterior width of vertex is the width between imens measured are preferably taken from the sample the eyes anteriorly in dorsal view (fig. 3, v); the synth- containing the holotype. They are presented as the ob- lipsis is the shortest distance between the eyes posteri- served range with sample mean in italics, or as the mean orly (fig. 3, s). The eyes have antero-laterally a chiti- value only. In new species the dimensions of the holo- nous extension, the hyperoche, its function is type are given in brackets after the range of specimens probably to prevent small grains of sand or silt from of the same sex, marked HT thus {HT ##}. If only two entering between head and anterior margin of prono- specimens of a sex were available for measurements tum. Although there some interspecific variation in only the range is given. In this case an eventual holo- the development of this structure exists, it does not 262 Downloaded from Brill.com10/07/2021 10:35:42PM via free access N L R: Review of Limnocoris seem to be useful for separating species. The ante- order to give an accurate impression of its structure, clypeus is a sclerite forming the anterior part of the we present Scanning Electronic Micrographs of a lat- head, just posterior of the rostrum. It is not recogniz- eral and a ventral view of the mesosternal carina when able as a separate sclerite in Naucoridae. The extent of sufficient material was available. Due to conditions of the frontal projection of the anteclypeus in front of the preservation the best view for a SEM may be from dif- labrum is measured in ventral view: the distance be- ferent angles, which explains the different orientation tween the suture between head and labrum and the in the figs.