Kryptochroma Machado, 2021

Machado, Miguel, Viecelli, Rafaela, Guzati, Catherine, Grismado, Cristian J. & Teixeira, Renato A., 2021, Kryptochroma: a new genus of bark-dwelling crab spiders (Araneae, Thomisidae), European Journal of Taxonomy 778, pp. 26-70 : 29-32

publication ID 10.5852/ejt.2021.778.1565

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scientific name

Kryptochroma Machado

gen. nov.

Kryptochroma Machado View in CoL gen. nov.

Type species

Stephanopis pentacantha Mello-Leitão, 1929 View in CoL . Designated here.


The species of Kryptochroma gen. nov. resemble some of those of Epicadus [e.g., Epicadus caudatus ( Mello-Leitão, 1929) and Epicadus tuberculatus (Petrunkevitch, 1910) ] by their cryptic bark-dwelling habitus with predominant brown or reddish-brown body coloration, and those of Epicadinus , especially by their small size (varying from approximately three millimeters of the total body length for males and nine to females) and spiny habitus (body covered by many setae and rugose teguments, and opisthosoma bearing stout conical projections) ( Fig. 2A–D View Fig ). However, they can be easily recognized and distinguished from Epicadus , Epicadinus and other genera of Stephanopinae by the presence of a pair of ventral macrosetae on their anterior patellae (I and II) ( Fig. 1D View Fig ), sensorial pits (three to five trichobothria surrounded by a small group of duster-shaped setae) on dorsal tibial depressions preceded by a strong plumose macroseta ( Fig. 1C View Fig ), and a pair of circular taints on the posterior slope of the prosoma ( Figs 3A View Fig , 4A View Fig , 7A View Fig ). Differently from Epicadinus , the species of Kryptochroma gen. nov. have five opisthosomal projections instead of three, and short leaf-shaped setae covering their entire body instead of long needle-shaped ones ( Fig. 1A–B View Fig ). Females present a flat epigynal plate, short copulatory ducts and a single pair of oval spermathecae ( Fig. 10C–F View Fig ); the male palp bears a pear-shaped tegulum with a short and fixed embolus, and a single tipped, stout and conical RTA ( Fig. 11C–F View Fig ).


The name of the genus is a combination of the Greek words ‘ kryptos ’ (κρυπτός) and ‘ chroma ’ (χρῶμα), which respectively mean ‘hidden’ and ‘color’. The name is a reference to the general color pattern of these spiders, which is associated to their cryptic behavior. Gender feminine.


PROSOMA. Granular surfaced due to the presence of spherical setae sockets ( Fig. 1A–B View Fig ); slightly longer than wide, pear-shaped and usually covered with organic particles.ALE almost two times as large as AME, prosoma coloration shows a gradient of brown and dark-yellow shades (predominantly reddish brown in Kryptochroma hilaris Machado & Teixeira gen. et sp. nov.), lighter on the posterior slope, where there is a pair of rounded spots close to the anterior border of the opisthosoma ( Figs 3A View Fig , 4A View Fig , 7A View Fig ); in some cases the individual has a yellow longitudinal line between the MS and PME ( Figs 3A View Fig , 5A View Fig , 7A View Fig , 9A View Fig ). Anterior eye row strongly recurved, AME close to each other, and posterior eye row procurved ( Fig. 11A–B View Fig ). Clypeus with a central pair of serrated macrosetae ( Fig. 1A View Fig ). Sternum scutiform, slightly longer than wide in females and as long as wide in males, with brush-shaped setae. Carapace with a conical medianposterior projection pointing backwards (except for K. hilaris gen. et sp. nov. and K. parahybana (Mello- Leitão, 1929) gen. et comb. nov., which have just an obtuse and slight elevation on the top of the thoracic area); opisthosoma short with five stout projections (two lateral pairs and one single and larger terminal projection), anal region and spinneret ring area projected backwards. Mouthparts: chelicerae with five equal-sized teeth; three on the promarginal row and two on the retromarginal. Labium truncated, slightly wider than long. Endites truncated, longer than wide, with scarce promarginal scopula.

LEGS. Anterior femora enlarged and bearing many conical setiferous tubercles, legs I and II stouter and longer than legs III and IV, femora I and II with dorsal and dorsolateral stout macrosetae in conical sockets. Tibia I and II with five pairs of ventral macrosetae, metatarsi I and II with three ventral and one dorso-distal pair ( Fig. 1E View Fig ). Tarsal claws curved, pectinated, unequal in number of teeth (mesial claw with numerous thin teeth and ectal having three stout ones); subungueal tufts scarce, with brush-shaped setae ( Fig. 3B View Fig ).

OPISTHOSOMA. Five short conical projections (two dorsolateral consecutive pairs, and a single caudal one), straight or slightly concave anterior border and rough surfaced, covered by leaf-shaped setae ( Fig. 1B View Fig ). Anal region and spinneret ring projected backwards, elongated.

GENITALIA. Palpus with cymbium and tegulum pear-shaped, without apophyses; RTA single tipped, stout and presenting grooves at the apex ( Figs 8D View Fig , 11D, 13D). The internal morphology of female genitalia is very conservative, presenting a single pair of reniform spermathecae without any accessory glands or coiled ducts ( Figs 3D View Fig , 4D View Fig , 7D View Fig , 10D View Fig , 12D, 16D); in ventral view the copulatory openings are excavated in relation to the rest of the surface of the genital area, separated by a septum and located close to the edges of the posterior margin of the epigynal plate ( Figs 10C View Fig , 12C, 16C).


Nine species distributed within the Neotropical Region: Kryptochroma gigas Machado & Viecelli gen. et sp. nov., Kryptochroma hilaris Machado & Teixeira gen. et sp. nov., Kryptochroma macrostyla (Mello- Leitão, 1929) gen. et comb. nov., Kryptochroma parahybana ( Mello-Leitão, 1929) gen. et comb. nov., Kryptochroma pentacantha ( Mello-Leitão, 1929) gen. et comb. nov., Kryptochroma quadrata Machado & Viecelli gen. et sp. nov., Kryptochroma quinquetuberculata ( Taczanowski, 1872) gen. et comb. nov., Kryptochroma renipalpis ( Mello-Leitão, 1929) comb. nov. and Kryptochroma septata Machado & Teixeira gen. et sp. nov.


Brazil (Amazonas, Bahia, Espírito Santo, Minas Gerais, Pará, Paraíba, Paraná, Pernambuco, Roraima, Rio de Janeiro, Rio Grande do Sul, Santa Catarina, and São Paulo) and French Guiana (Cayenne, Maripasoula, Saint-Élie and Saül) ( Figs 9 View Fig , 18).


Each one of the color variations documented here (from greyish-green to dark-yellow or predominantly reddish-brown), as well as the stained (e.g., opisthosoma of K. septata sp. nov. – Fig. 16A View Fig ) and striped patterns (e.g., prosoma of the specimen in the Fig. 2A View Fig ) were observed in all species. Therefore, since all species of Kryptochroma gen. nov. can present any combination of tegument hue, is it virtually impossible to identify them solely based on their color.











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