Kunziana irengis Pretzmann 1971
Creators: name: Magalhães, Célio
name: Türkay, Michael
name: Means, Bruce
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Pseudothelphusidae
Kunziana
Kunziana irengis

description: Kunziana irengis (Pretzmann, 1971)
(Figs. 1, 2 D–H)
Eudaniela (Kunziana) irengis Pretzmann, 1971: 1. ― Pretzmann 1972: 22, figs. 65-68, 92-94. ― Rodríguez 1982: 191. ― Ng et al. 2008: 177.
Material examined. Guyana, Potaro-Siparuni region: male holotype (cb 27.4 mm, cl 16.1 mm); 1 female paratype (cb 22.6, cl 13.7), NHM 1905:11:2:4/13, Ireng District, Ireng River, 01.V.1905, coll. C. Bovallius; 1 male (cb 16.8, cl 11.0), INPA 1677, clear water, tumbling rocky mountain stream on the lower, southern slopes of Mt. Kopinang on the Wokomung Massif [04º59’N 59º54’W], ca. 1077 m elevation, 5.XII.2006, coll. D.B. Means, M. Kalamandeen and W. Smith; 3 females (cb 20.7, cl 13.0; cb 21.5, cl 13.4; cb 22.7, 14.1), INPA 1678, small first-order muddy creek on southern flank of Mt. Kopinang on the Wokokung Massif, ca. 1485 m elevation, 6.XII.2006, coll. D.B. Means, M. Kalamandeen, L. Fredericks and W. Smith.
Comparative material examined. Kingsleya latifrons (Randall, 1840): 1 male, INPA 389, French Guiana, Cayenne, Trois Sauts [02º15’N 52º53’W, upper rio Oyapoque], 1985, coll. Grenard; 1 male, SMF 13701, Brazil, Amazonas, rio Uatumã, igarapé Arraia, 27.i.1985, coll. unknown. ― Fredius fittkaui (Bott, 1967): male holotype, SMF 2879a, Brazil, Amazonas, Xamata, upper rio Negro (Gebirgsbach Chamata, am oberer Rio Negro, Chamata-Gou), 17.i.1963, coll. E.-J. Fittkau; 2 males (cb 32.1, cl 22.6; cb 77.0, cl 50.5), INPA 853, Brazil, Amazonas, São Gabriel da Cachoeira [00º07’S 67º04’W], morro Fortaleza, 2.iv.1990, colls. J. Zuanon & P. Petry; 1 male juvenile (cb 22.5 cl 15.6), INPA 860, Brazil, Amazonas, município de Barcelos, Toototobi village, igarapé unnamed, 01º45’57”N 63º37’02”W, 13.viii.1994, colls. L.S. Aquino & U.C. Barbosa. ― Fredius beccarii (Coifmann, 1939): 1 male (cb 41.9, cl 27.3) 1 male juvenile (cb 23.7, cl 16.1), INPA 1542, Guyana, Melville, Rupununi River, 1913, unknown collector.
Type locality. Guyana, Ireng District, Ireng River. The Ireng (or Maú) River flows through the Pakaraima Mountains and marks part of the border between Guyana and Brazil in the northeastern part of the Brazilian state of Roraima. This river is the northernmost tributary of the Amazon Basin, and is an affluent of the Rio Tacutu, which joins the Rio Uraricoera to form the Rio Branco, an affluent of Rio Negro.
Diagnosis. See diagnosis of the genus.
Redescription of the holotype. Small-sized species (adult specimens with cb <30 mm). Carapace outline ellipsoid, widest at its middle (ratio cb/cl 1.70); dorsal surface smooth, slightly convex in both directions, regions poorly defined. Pair of gastric pits distinct, very close to each other on metagastric region. Cervical grooves deep, narrow, nearly straight, extremities ending near anterolateral margin. Postfrontal lobules low; median groove indistinct between postfrontal lobules. Surface of carapace between front and postfrontal lobules smooth, slightly inclined anteriorly and medially. Upper border of front marked by low ridge fringed with faint tubercles, slightly arched in frontal view, slightly convex in dorsal view, with shallow median notch; lower border carinate, gently sinuous in frontal and dorsal views, distinctly more projecting anteriorly than upper one, especially on outer parts; lower frontal border continuous with upper margin of orbit. Upper orbital margin smooth; lower orbital margin fringed by row of papillae (left orbit with deep wound on lower margin); exorbital angle obtuse, low. Lateral margins of carapace fringed by set of small denticles, slightly larger medially; posterolateral margins rounded posteriorly, marked by faint suture (Fig. 1 A). Epistome narrow, scarcely pilose; epistomial tooth triangular, deflexed, borders rounded, smooth. Suborbital, subhepatic regions of carapace sidewall smooth; pterygostomial regions sparsely pilose, rather rugged by patch of granules proximally.
Endopod of third maxilliped with outer margin of ischium slightly convex, inner margin nearly straight. Exopod short, 0.19 times the length of endopod ischium outer margin (Fig. 1 B). Aperture of efferent branchial channel wide, subquadrate (Fig. 1 C).
Chelipeds heterochelous, left larger than right one. Larger cheliped (detached from body) with merus subtriangular in cross section; superior margin rounded, with irregular transversal, short rows of granules; mesial margin lined with longitudinal row of tubercles, increasing in size distally; lateral margin rounded, with indistinct row of faint tubercles. Carpus with inner margin proximally with row of tubercles, prominent blunt spine medially, nearly smooth distally; outer margin rounded, smooth. Palm relatively narrow (length/ breadth ca. 1.71), smooth on both sides. Fingers slightly gaping; propodal finger with 2 blunt, conical teeth, interspaced with smaller ones; dactylus with 3 blunt, conical teeth proximally; tip broken. P2 (left) missing; P4, P5 (left) barely attached to body; P3–P5 (right) partially broken; dactylus of attached P2-P5 each bearing 5 longitudinal rows of sharp, corneous spines, increasing in size distally.
Thoracic sternum considerably damaged by deep longitudinal cut in the middle, with a hole in the position of detached left cheliped.
All abdominal somites and telson free. Lateral margins of male telson (Fig. 1 D) distinctly concave, serrated; tip rounded, relatively narrow, ratio length of telson/breadth of proximal border: 0.56.
Male first gonopod (Fig. 1 E–I) straight, enlarged distally due to well developed mesial process. Marginal suture straight, situated on mesial side, bearing few setae proximally. Marginal process rather long, strongly curved to lateral side, ending juxtaposed to proximal part of apical plate, not projected distally over apical field of spines. Mesial process large, semicircularly shaped in mesial view, displaced to more apical position, with conical spine on distal portion pointing in caudomesial direction, its distal border clearly enlarged in caudal view, with some spinules apically. Mesial process separated from apical plate by slight concavity. Apical plate very strongly deflexed, bilobed; proximal lobe partially folded, forming narrow, digitiform projection pointing in latero-cephalic direction, slightly oriented towards basal side; distal lobe with rounded tip slightly shorter than proximal one. Field of apical spines moderately developed, narrow, basally oriented, bordered by “mesial” and “lateral” borders of apical plate but opened both proximally and distally.
Second gonopod slightly longer than first gonopod (ca. 1.15 times the length of first gonopod); flagellum slender, tapering, tip compressed.
Distribution. The few records available point to a narrow distribution in the southwestern region of Guyana along the Ireng River and upper Potaro River basins. As Kopinang Mountain (part of the larger Wokomung Massif) is located between the left bank of the Ireng River and the left bank of the Potaro River, its distributional area probably encompasses both the Amazon and the Essequibo River basins. Its occurrence in the Brazilian side of the Ireng River basin is expected since this river marks the border between Guyana and Brazil.
Ecological notes. The INPA 1677 male specimen was collected in a clear water mountain stream flowing through large rocks, boulders and cobbles of Roraima sandstone, with some gravel and sand, but no organic matter because of the swift current (Fig. 3). The stream gradient is a slope of about 10 to 15 degrees, cascading over boulders and fallen trees. The three females included in INPA 1678 were collected by using dip nets in leaf packs in the muddy streambed of a first-order creek with a gentle slope (Fig. 4). This stream, a tributary of the larger stream where the INPA 1677 specimen was collected, is intermittent, flowing very slowly over a relatively flat stretch for about 30 m before disappearing underground into very large rocks up- and downstream. The streambed was muddy with organic material, sand, and some clay. Quiet, shallow pools with leaves on the bottom are common at the site.
Remarks. Kunziana is assigned generic rank due to the peculiar combination of a strong transversal torsion towards the cephalic side of the first gonopod’s apical plate and a longitudinal bending towards the basal portion resulting in a field of apical spines that face the basal part of the stem (Fig. 1 E, H). Extreme twisting of the gonopod apical processes in K. irengi is not seen in any other genus of Kingsleyini. The species otherwise has characters typical of Kingsleyini: the exopod of maxilliped 3 is reduced to less than three tenths of the length of the ischium, the mesial process has a dentiform lobe, the marginal process is curved and projects laterally, and the apical field of spines is elongated and bordered by two crests (Rodríguez 1982). However, the field of spines in K. irengis is clearly directed basally rather than laterally or anteriorly.
The possible homologies in the gonopod structures suggest that the genus Kunziana is closest to Kingsleya Ortmann, 1897. A morphological comparison of the left gonopod of Kunziana irengis and Kingsleya latifrons (Fig. 2), a species that also occurs in the upper Rio Branco basin (Magalhães 1986), indicates that the apical plate, which in K. latifrons is situated obliquely to the longitudinal axis of the stem, undergoes an approximately 90º rotation from a caudal towards a cephalic position and another 90º bend from a longitudinal to a transversal position in K. irengis (Fig. 2 A, D). This torsion causes the apical field of spines, which is positioned longitudinally on the caudal side in the former species (Fig. 2 C), to take a transverse position towards the cephalic side and facing the basal part of the stem, appearing “upside down” in the latter (Fig. 2 F, H). The apical plate consists of two partially juxtaposed lobes in both genera, but the proximal lobe is shorter than the distal one in K. latifrons (Fig. 2 B, C), while it is longer in K. irengis (Fig. 2 F, H).
The marginal process is long and distinctly separated from the distolateral border of the stem in K. irengis (Fig. 2 D, F) while it is relatively short and only slightly produced over the distolateral border of the gonopod in K. latifrons (Fig. 2 A–C). The mesial process is clearly separated from the apical plate in both species, but this separation is marked by a deep notch in K. latifrons and by a slight concavity in K. irengis (Fig. 2 B, D). In the latter, it displays a distal enlargement probably as a consequence of the apical plate’s strong torsion while this portion is discrete in the former (Fig. 2 A, D). Both species bear a few spinules in this area. Similarly, the two species have a strong conical spine on the distal part of the mesial process Fig. 2 A–F), but this spine is directed caudally in K. irengis but mesially in K. latifrons.
Affinities of Kunziana with Microthelphusa Pretzmann, 1968, can also be discerned, particularly when the first gonopod of Kunziana is compared with the one of M. rodriguezi Pretzmann, 1968. This last species is known from a single record from the Rupununi River basin, a tributary of the upper Essequibo River, in southern Guyana (Pretzmann 1968). The redescription and illustrations of its gonopod (Suárez 2006: fig. 4) show that both species share (1) a similar long and strongly bent laterally marginal process, which is clearly detached from the distolateral border of the main stem; (2) a mesial process with a strong conical spine, and separated from the apical plate by a distinct concavity; and (3) a bilobed apical plate. The apical plate is much more developed in M. rodriguezi and does not exhibit the complex torsion seen in the K. irengis gonopod. Furthermore, the distal lobe (= cephalic lamella sensu Suárez 2006) is much wider and longer than the proximal one (= caudal lamellae sensu Suárez 2006). As in Kingsleya, the apical field of spines is positioned longitudinally in Microthelphusa.
The affinities with the genus Fredius are less evident. At least three species of this genus occur in Guyana: F. b e c c a r i i (Coifmann, 1939), F. fittkaui (Bott, 1967), and F. reflexifrons (Ortmann, 1897). Their gonopods have the field of apical spines delimited by marginal borders, but it is longitudinally positioned and laterally directed (Rodríguez 1982: 185, fig. 129; Magalhães & Rodríguez 2002: 679, fig. 1; 683, fig. 2). Their gonopods also bear a mesial process, which is less developed and reduced to a conical spine in Fredius spp. Moreover, the marginal process, which is not well differentiated and continuous with the caudal surface in Fredius spp., is well produced from the caudal surface and strongly curved to the lateral side in Kunziana irengis (Fig. 1 E, F, I). Furthermore, the specimens of K. irengis examined here can not be considered immature specimens of Fredius spp., as their gonopods are fully developed. Fredius fittkaui and F. reflexifrons are among the largest-size species of the family, reaching a carapace breadth of around 100 mm (Magalhães & Rodríguez 2002) while the available specimens of K. irengis do not surpass cb 30 mm. Male specimens of Fredius spp. of this size are immature and their gonopods are incompletely developed. Even so, the comparison of their gonopods shows evidence of the differences mentioned above.
description: Published as part of Magalhães, Célio, Türkay, Michael & Means, Bruce, 2009, The status of Kunziana Pretzmann, 1971 (Crustacea: Decapoda: Pseudothelphusidae), with a redescription of the holotype of K. irengis Pretzmann, 1971, pp. 40-48 in Zootaxa 2276 on pages 41-47, DOI: 10.5281/zenodo.191071