Katasophistes , Giron, Jennifer C. & Short, Andrew Edward Z., 2018

Giron, Jennifer C. & Short, Andrew Edward Z., 2018, Three new genera of acidocerine water scavenger beetles from tropical South America (Coleoptera, Hydrophilidae, Acidocerinae), ZooKeys 768, pp. 113-158: 126-128

publication ID


publication LSID


persistent identifier


taxon LSID


treatment provided by

ZooKeys by Pensoft

scientific name


gen. n.

Katasophistes  gen. n. Figs 9, 10, 11, 12, 13, 14

Type species.

Katasophistes merida 

Differential diagnosis.

Medium to small beetles, total body length 2.7-4.5 mm, width 1.7-2.4 mm. Color orange brown to dark brown, rather uniform along body regions. Body shape oval to elongated in dorsal view; moderately convex in lateral view (see Figs 9-10). Antennae with nine antennomeres (e.g., Fig. 10C). Maxillary palps curved inward, moderately long to long (e.g., Fig. 10D, H). Each elytron with five rows of deep/large systematic punctures (Fig. 10A; not as evident in K. charynae  , K. cuzco  and K. superficialis  ); elytra without sutural striae, with outer margins slightly flared; serial punctures not evident. Posterior elevation of mesoventrite, with a well-defined, curved transverse ridge (Fig. 11A). Posterior femora glabrous at most along apical third. Fifth abdominal ventrite apically truncate to slightly emarginate, with stout setae (see Fig. 11 C–E).

At first glance the genus may appear similar to some species of Chasmogenus  , however the lack of sutural striae easily separates the two. The enlargement of the rows of elytral systematic punctures is also rare within the Acidocerinae  (found in some Chasmogenus  and Agraphydrus  ) and will separate it from other New World Helochares  , with which it may also be confused.


Body oval to elongate, weakly to moderately convex (e.g., Figs 9F, 10F), coloration rather uniform along body regions, orange brown to dark brown, often with maxillary palps slightly paler. Head. Frons and clypeus (e.g., Fig. 9D) with moderately marked ground punctures, irregularly and rather densely distributed over the surface, accompanied by seta-bearing systematic punctures, particularly noticeable on frons behind frontoclypeal suture and around inner margins of eyes, and on lateral areas of clypeus; surface between punctures smooth and shiny; anterior corners of clypeus roundly angulated; anterior margin of clypeus widely roundly emarginate. Eyes subquadrate in dorsal view (e.g., Fig. 10H). Labrum wide, fully exposed, nearly half as long, and collinear to clypeus (e.g., Fig. 9D); dorsal surface slightly convex, with scattered fine punctures; anterior margin mesally slightly emarginate and barely bent inwards; lateral and anterior margins fringed by rather long setae. Temporae densely covered by very short and fine setae (hydrofuge pubescence). Mentum parallel sided, with lateral oblique longitudinal ridges; anterior margin with wide, deep, concave median impression, not demarcated by a transverse carina. Submentum rather flat and pubescent at base, glabrous, shiny and ascending at apex, with sparse rather long setae near limit of pubescent/glabrous line; ocular ridge well-developed (e.g., Fig. 9C). Maxilla (e.g., Fig. 9C) with ventral surface of cardo and stipes smooth and shiny, with scattered and shallow punctures (basal outer margin of cardo with a fringe of fine and rather long setae in K. merida  ); outer dorsal margin of palpifer with a row of stiff decumbent spiniform setae; limit between cardo and stipes oblique; maxillary palps brown to orange, slender, longer than antennae (slightly so and stout in K. merida  ); apex of palpomere 3 bearing sensilla. Mandibles with apex bifid (observed in K. merida  and K. charynae  ). Labial palps yellowish, nearly as long as mentum, dorsoventrally flattened; palpomere 2 with inner and outer margin convex apicad of midpoint; palpomere 3 digitiform, with a long subapical seta on outer corner. Antennae (e.g., Fig. 10C) with nine antennomeres, either similar or paler than general coloration of head; antennomere 1 anteriorly projected near base, almost reaching midpoint of ventral surface of eye (not reaching cardo-stipes joint), nearly 1.4-1.8-times longer than antennomere 2; antennomere 2 nearly as long as antennomeres 3-4 combined; antennomere 6 forming a well differentiated, only slightly asymmetric cupule; antennomeres 7-9 similar in size (8 shortest, 9 longest) and shape, slightly flattened (less so in K. merida  ), forming a loosely articulated, pubescent club; apex of antennomeres 7-9 with few scattered setae longer than general pubescence of club. Thorax. Pronotum widest at base, narrowed anteriorly, with anterior and posterior margins only slightly sinuate; surface evenly convex, ground punctation moderate, uniformly dense, with surface between punctures smooth and shiny; seta bearing systematic punctures forming paired anterolateral semicircles. Scutellar shield of moderate size, triangular, nearly as long as wide, with punctation as in pronotum. Prosternum (e.g., Fig. 9C) nearly as long as 2/3 of length of a coxa, weakly convex to only slightly ascending longitudinally on central area; anterior margin of prosternum mesally projected as a wide, roundly pointed triangle, usually with a low carina along midline of projection; surface of prosternum covered by rather long, fine, scattered setae; intercoxal process projected from posterior margin of procoxal cavities, rectangular shaped in outline, with pyramidal surface. Mesoventrite not fused to mesepisterna, with anterior margin 0.2-times as wide as anterior margin of mesepisternum; anterior rib of mesoventrite bearing a medial semitriangular, pearlescent macula; posterior elevation of mesoventrite with a well-defined, curved transverse ridge, sometimes swollen at midpoint (as in K. cuzco  ); surface of mesoventrite reticulated for the most part; mesepisternum obliquely widely concave, with reticulated surface; mesepimeron trapezoid, with reticulate and pubescent surface. Mesofurca (examined in K. merida  ) with short arms, 0.6-times length of mesocoxae; apical half of arms free irregularly explanate, with outer corners sharply pointed. Metaventrite posteromesally elevated, with elevation rather flat; surface of metaventrite reticulate and pubescent, except for postero median and glabrous patch. Metepisterna 3-4-times longer than wide, only slightly narrowing posteriorly. Metepimeron triangular and acute. Metafurca (examined in K. merida  , Fig. 11B) 1.6-times wider than long, with furcal arms (fa) slightly longer than stalk (s); stalk triangular (wider near the crux (c), gradually narrowing ventrally), with paired longitudinal keels extending along basal third of posterior face, and a well-developed median keel on anterior face extending to anterior margin of dorsal sheets (ds); outer margins of stalk diverging from base towards proximal third of furcal arms; furcal arms somewhat trapezoid, with apex (hemiductus (h)) only slightly explanate, obliquely positioned; anterior tendons (at) inserted at basal third of dorsal edge of furcal arms; dorsal sheaths well-developed, slightly wider than widest point of lateral sheaths (ls). Elytra. Surface even (without elevations or depressions), serial punctures not clearly defined (e.g., Fig. 9E), not impressed into striae; seta bearing systematic punctures rather enlarged and deep (less strikingly so in K. charynae  , K. cuzco  and K. superficialis  ), forming five longitudinal rows, fifth row very close to outer margin of elytron; elytral margins slightly flared. Epipleura well-developed, slightly oblique, with sparse setae, anteriorly wide, gradually narrowing posteriorly, extending up to line of posterior margin of first abdominal ventrite; pseudepipleura well-developed, perpendicularly positioned, nearly half as wide as anterior portion of epipleura, extending along entire outer margin of elytra. Hind wings well-developed. Legs. All femora with dense pubescence, at least along basal two thirds, remainder of surface glabrous, shiny and slightly reticulated; all femora antero-posteriorly flattened; metafemora with rather weak tibial grooves. Tibiae slender, weakly flattened, with well-developed spines; protibiae with a median longitudinal row of long spathulate setae along anterior surface. All tarsi with five tarsomeres, bearing long apical hair-like setae on dorsal face, and two lateral rows of spines and/or hair-like spines on ventral face of tarsomeres 2-4; protarsomeres 1-4 similar in size and shape; meso- and meta tarsomeres with tarsomere 2 nearly as long as tarsomere 5; tarsomere 5 approximately as long as tarsomeres 3-4 combined, without spines on ventral face; claws rather large, curved; empodium well-developed, bearing a pair of long, curved apical setae. Abdomen. Abdomen with five ventrites, medially weakly convex; all ventrites reticulated, with uniform, dense, fine pubescence; posterior margin of fifth ventrite truncate to mesally weakly emarginated, set with a row of thick, flat spine-like setae (see Fig. 11 C–E). Aedeagus (Fig. 12) nearly parallel sided, with basal piece between 0.5 and 1.1-times the length of parameres; median lobe wider than each paramere, gradually narrowing apically, with a conspicuous median longitudinal sclerotization, and well-developed lateral basal apodemes; apex of median lobe acute; parameres nearly as long as median lobe, with apical setae; gonopore preapically situated.


The immature stages are unknown.


Named from the Greek word katasophistes, meaning trickster, in reference to the disparity of the general appearance of some of the known species. Name to be treated as masculine.


Venezuela ( Mérida), Ecuador (Pastaza), Peru (Cuzco, Madre de Dios). See Fig. 13.


Species in this genus exhibit a combination of ecologies: K. merida  is restricted to seepage habitats, while the type series of K. superficialis  was collected from forested stream pools with abundant detritus. See Fig. 14.

Characters of taxonomic importance for Katasophistes  .

With the exception of the enlarged elytral systematic punctures, there is nothing particularly remarkable about the external morphology of Katasophistes  . Careful examination of the elytral systematic punctures is needed in order to recognize K. charynae  , K. cuzco  , and K. superficialis  .

Punctation. The most prominent feature of Katasophistes  is the enlargement of the elytral systematic punctures, which is evident in K. merida  (Fig. 10A, B), but much less so in K. charynae  , K. cuzco  and K. superficialis  . One way to recognize the enlarged elytral systematic punctures would be by spotting the long setae that systematic punctures bear.

Posterior elevation of mesoventrite. It is usually well-defined and shaped as a curved transverse ridge. Only in K. cuzco  is this transverse ridge additionally medially swollen, as to form a low bump.

Aedeagus. In Katasophistes  the aedeagus exhibits the same general shape of the median lobe, combined with a wide variety of shapes of the parameres (see Fig. 12).

Key to the species of Katasophistes