Redescription and neotype designation of Suphis fluviatilis Guignot, 1948 (Coleoptera: Dytiscoidea: Noteridae) and notes on other species of the genus.

Suphis fluviatilis Guignot, 1948 was described based on a single female specimen, and according to the author, the type was deposited in the Museum National dHistoire Naturelle (Paris, France). However, the diagnostic features of the specimen deposited under this name and provided with the respective labels deviate considerably from those given by Guignot in his original description. It is shown that this specimen belongs to Suphis notaticollis Zimmermann, 1921, confirming previous observations by Luis Grosso in 1980. Thus, a neotype of S. fluviatilis is designated to avoid instability of the nomenclature by the impending synonymy of S. fluviatilis with S. notaticollis. Suphis fluviatilis is redescribed in detail, including illustrations of the main diagnostic characters. The species is compared with other Neotropical Suphis species, in particular with S. notaticollis. Additionally, the male genitalia of Suphis intermedius Rgimbart, 1903 are described for the first time, and a first record from Paraguay is given.

Description and chaetotaxic analysis of the larval instars of Hydrocanthus debilis Sharp, 1882 (Coleoptera: Noteridae).

All larval instars of the burrowing water beetle species Hydrocanthus debilis Sharp, 1882 are described and illustrated, including morphometric and chaetotaxic analyses of the cephalic capsule, head appendages, legs, last abdominal segment, and urogomphus. Larvae of this species have many small dark dorsal maculae on the body, which easily distinguishes it from other known species of the genus except H. socius Sahlberg, 1884. Larvae of H. debilis can easily be separated from those of H. socius by their smaller size, the length of parietal seta PA13 relative to seta PA14, and the relative distance between egg bursters.

Suphisellus grossoi sp. n., a new burrowing water beetle from South America, and notes on S. flavolineatus (Régimbart, 1889) and S. grammicus (Sharp, 1882) (Coleoptera: Noteridae).

Suphisellus grossoi sp. n. is described from the Reserva Natural del Bosque de Mbaracayú, Canindeyú department, Paraguay. Diagnostic characters are described and illustrated in detail. New records are provided for S. flavolineatus (Régimbart, 1889) and S. grammicus (Sharp, 1882), which are also briefly diagnosed. Suphisellus melzeri Zimmermann, 1925 is proposed as a junior subjective synonym of S. flavolineatus (syn. n.), and lectotypes are designated for both taxa.

Characterization and mapping of sensilla on the head appendages of noterid larvae (Coleoptera: Noteridae), and development of a preliminary biometric method for taxa delimitation.

Larvae of the burrowing water beetle family Noteridae are distributed worldwide and are often abundant in a broad range of aquatic habitats, playing an important role in structuring freshwater communities, yet they have remained among the most poorly studied groups of aquatic beetles. Studies on sensillar equipment of aquatic insect larvae are largely lacking, despite their potential use in phylogeny and biometric identification methods. In this article, the external morphology and distribution of sensilla on the head appendages of first instar larvae of selected genera of Noteridae were examined using scanning electron microscopy. Seven main types were distinguished based on their morphological structure: basiconica (3 subtypes), campaniformia (2 subtypes), chaetica (7 subtypes), coeloconica (6 subtypes), coniform complex (2 subtypes), placodea, and styloconica (3 subtypes). The apex of the labial palpus was found to be the most variable and informative region in regard to the number, relative position, and topology of sensilla. Fingerprint models were, therefore, generated for this region in each of the studied genera, allowing their identification.

Larval morphology and analysis of primary chaetotaxy in the genus Suphis Aubé, 1836 (Coleoptera: Noteridae).

The three larval instars of Suphis cimicoides Aubé, 1837 are described and illustrated, including morphometric and chaetotaxic analyses of the cephalic capsule, head appendages, legs, last abdominal segment and urogomphus. A preliminary ground plan of primary chaetotaxy for noterid larvae is presented for the first time, based on the species described herein and examination of larvae of the genera Hydrocanthus Say, 1823 and Suphisellus Crotch, 1873. This ground plan is compared with previous systems proposed for other adephagan families. Larvae of Noteridae can be distinguished from those of other families of Hydradephaga by the following combination of characters: (1) antennomere 3 with a rugged area on distal portion; (2) abdominal segment VIII with a U-shaped wavy membranous area ventrally; (3) absence of pore FRd; and (4) presence of seta AB16. Several sensilla present in noterid larvae (notably setae TR2 and TA1 and pores PAl, PAm, COd, TRb and FEb) are absent in larvae of Meruidae. On the contrary, parietal seta PA5 is present in Meruidae but absent in Noteridae. The presence of pore COc in Noteridae may indicate that this family has retained the ancestral condition found only in Carabidae. On the other hand, the absence of setae FE7, FE8, FE9 and FE10 in Noteridae is similar to the condition found in Carabidae, Gyrinidae and Meruidae.