Neostrengeria auderseti, Campos & Lasso & Jaramillo, 2025

Campos, Martha R., Lasso, Carlos A. & Jaramillo, Alexis, 2025, A new species of freshwater crab of the genus Neostrengeria Preztmann, 1965 from Colombia (Malacostraca: Decapoda: Pseudothelphusidae), including an analysis of the geographical distribution of the species of the genus, Zootaxa 5660 (1), pp. 89-101 : 90-96

Neostrengeria auderseti sp. nov.

( Figures 1–4 )

Material examined. Holotype: male (CL17.0 mm, CW 29.4 mm) ( ICN-CR 3720 ), Colombia, Santander Department, La Aguada Municipality, El Nitro cave , elevation 1790 m, 6°10’32”N 73°30’52.3”W, coll. C.A. Lasso, 9 August 2024 . Paratypes: 7 males (CL 12.6–14.9 mm, CW 21.0–26.0 mm), 4 females (CL 13.7–22.2 mm, CW 24.9–40.6 mm), 7 juveniles ( ICN-CR 3721 ) , 2 males (CL 12.1–12.2 mm, CW 19.8–20.1 mm), 8 juveniles (IAvH–I–7517), same locality data as for holotype .

Diagnosis. Third maxilliped with exopod 0.6 to 0.7 times length of ischium ( Fig. 2C ). G1 widest mid-basally; bent dorsally in lateral view; mesial side with nearly rounded basal expansion, straight mid-subdistally, and triangular subdistal protuberance; marginal suture straight, extending beyond the apex with a prominent sub-triangular end, forming a rounded lobe proximally with long setae; lateral lobe semi-circular, foliose, projected distally, with posterior surface excavated, and external margin sinuous, separated from accessory lobe by deep notch; accessory lobe shorter than lateral lobe, elongated, bent ventro-dorsally, narrow basally, with sinuous subdistal internal margin, nearly rounded distally ( Fig. 3 A-D); apex outline elongated in distal view, with ventro-lateral border expanded into distal projection, ends acutely laterally, dorsal border sinuous, with a prominent proximal anterior spine; mesial lobe sub-triangular in distal view, projected as an acute spine dorsally ( Fig. 3E ).

Description of holotype.Carapacewithstraight,wide,deepcervicalgrooves,endingsomedistanceoflateralmargin; antero-lateral margins with shallow depression behind outer orbital angle, and8papillae before cervical grooves;lateral marginswithapproximately22semi-acutetubercles,decreasinginsizeposteriorly;postfrontallobesoval;mediangroove shallow, wide; dorsal surface of carapace smooth, covered by small papillae, and regions well demarcated ( Fig. 1A ); frontal area regularly sloping downwards, front high, vertical, bilobed in dorsal view, lower margin strongly sinuous in frontal view, visible in dorsal view, conspicuously thickened with row of coalescent papillae; lower orbital margins each fringed with rounded tubercles; epistome narrow, lower margin moderately arched, epistomial tooth prominent, sub-triangular, rounded distally; buccal frame subquadrate; pterygostomial region strongly pubescent, with papillae ( Fig. 2A ). Third maxilliped with rounded angle on distal half of external margin of merus, exopod 0.6–0.7 times length of ischium ( Fig. 2C ). Orifice of efferent branchial channel subquadrate, open, with three spinules on superior angle of lateral lobe of epistome ( Fig. 2B ).

Chelipeds heterochelous; right cheliped larger than left, merus of right cheliped with 3 crests: upper crest with rows of tubercles of varying sizes, internal lower crest with a row of 7 large, rounded tubercles, diminishing proximally, external lower crest with a row of papillae; carpus with rounded subdistal spine, followed by 3 rounded tubercles; palms of both chelipeds smooth, palm of larger (right) cheliped moderately swollen, fingers 1.2 times length of palm, slightly gaping when closed, tips crossing; palm of smaller cheliped moderately swollen, fingers 1.2 times length of palm, not gaping when closed, tips crossing ( Figs. 1A, B , 2D ). Walking legs (second to fifth pereopods) slender, dactyli each about 1.4 times as long as propodi, with 5 longitudinal rows of large spines diminishing in size proximally; arrangement of spines on dactylus of all pereopods as follows: antero-lateral, antero-ventral rows each with 5 spines, and a proximal papilla, external row with 5 spines, postero-ventral, postero-lateral rows each with 4 spines ( Fig. 1A, B ).

Episternites sub-triangular, partially fused with sternites, with well-defined suture lines, extending to mesial region; sterno-abdominal cavity concave, midline of sternum short, deep, restricted to sternite VIII, sternites V, VI with a deep concavity that receive distal processes of G1; pleon sub-triangular, with a fine pubescent margin, well-differentiated somites, and sinuous suture lines, first abdominal segment narrow, increasing in size towards the sixth; telson sub-triangular, smooth surface, and pubescent margin ( Fig. 1B ).

G 1 in ventral view widest mid-basally; bent dorsally in lateral view. Mesial side with nearly rounded basal expansion, straight mid-subdistally, and triangular subdistal protuberance. Marginal suture straight, extending beyond the apex with a prominent sub-triangular end, forming a rounded lobe proximally with long setae. Lateral lobe semi-circular, foliose, projected distally, with ventral surface excavated, and external margin sinuous, separated from accessory lobe by deep notch. Accessory lobe shorter than lateral lobe, elongated, bent ventro-dorsally, narrow basally, with sinuous subdistal internal margin, nearly rounded distally. Lateral margin concave through apical to mid-portion, and sinuous basally ( Fig. 3A–D ). Apex outline elongated in distal view, with ventro-lateral border expanded into distal end, fringed with rounded tubercles, ends acutely laterally, dorsal border sinuous, with a prominent proximal dorsal spine, and two conspicuous setae on internal basal border ( Fig. 3E ). Mesial lobe triangular in distal view, projected dorsally as an acute spine. Meso-ventral projection of spermatic channel bilobed with external finger-like papilla, and sub-triangular papilla internally. Spermatic channel with conspicuous rows of spinules ( Fig. 3D, E ).

Coloration. The freshly-alcohol preserved holotype is brown (near Olive Brown, 28) with yellow specks (near Cinnamon, 123A) on the dorsal side of the carapace. The walking legs dorsally brown (near Olive Brown, 28) with yellow specks (near Cinnamon, 123A), ventrally yellow (near Yellow Ocher, 123C). The chelae brown dorsally (near Olive Brown, 28) with yellow specks (near Cinnamon, 123A), ventrally yellow (near Yellow Ocher, 123C). The ventral surface of the carapace is yellow (near Yellow Ocher, 123C).

Habitat. The specimens were collected manually from beneath rocks in a section of El Nitro cave, located in the Magdalena basin, specifically in the Sogamoso River sub-basin ( Fig. 5 ). This area is characterized by rocky formations and is situated in the foothills of the Serranía Los Yariguíes. The climate is temperate-humid with temperatures ranging from 12–17°C.

Etymology. The species is named in honor of Jesús Fernández Auderset, a Spanish-Swiss speleologist and active explorer and researcher of Colombia’s cave systems. The name is use as a noun in apposition.

Remarks. Adult male specimens of N. auderseti sp. nov. are smaller than females, with a size range of (CL 17.0– 12.6 mm, CW 29.4–21.0 mm) for males, and (CL 22.2– 13.7 mm, CW 40.6– 24.9 mm) for females. This species is considered troglophilic, as some specimens were found outside the cave.

Neostrengeria auderseti sp. nov. shares similarities in the shape of the G1 with Neostrengeria niceforoi ( Schmitt, 1969) (see Campos 2014: fig. 204A–E). The main distinguishing features between the two species in terms of their G1 morphology are as follows: (1) in N. auderseti sp. nov. the mesial side features a nearly rounded basal expansion, continues straight mid-subdistally, and ends in a triangular subdistal protuberance ( Fig. 3A, D ) (versus N. niceforoi has a strongly convex mid-basal expansion on the mesial side, followed by a depression, and ending in a small semi-acute sub-distal protuberance; Campos 2014: fig. 204B, D); (2) in N. auderseti sp. nov. the marginal suture is straight, extending beyond the apex with a prominent sub-triangular projection ( Fig. 3A ) (versus N. niceforoi has a strongly sinuous marginal suture, bearing 8 to 10 acute spines from the sub-distal to the apex portion; Campos 2014: fig. 204B); (3) in N. auderseti sp. nov. the lateral lobe is semi-circular, and projected distally ( Fig. 3A, D ) (versus N. niceforoi has a nearly circular lateral lobe, and projected laterally; Campos 2014: fig. 204B, D); (4) in N. auderseti sp. nov. the ventro-lateral border of the apex expands into a distal projection, fringed with rounded tubercles, and is ending acutely laterally, the dorsal border is sinuous, with a prominent proximal dorsal spine, and two conspicuous setae on the internal basal border, the meso-ventral projection of spermatic channel is bilobed with external finger-like papilla, and sub-triangular papilla internally ( Fig. 3E ) (versus N. niceforoi has 8–10 acute spines on the ventro-lateral border of the apex, diminishing in size towards the lateral border, the dorsal border has two spines separated by a deep depression, the meso-ventral projection of spermatic channel is also bilobed, but features an external spinule and a rounded internal papilla; Campos 2014: fig. 204D, E).

The two species also differ in the length of the exopod of the third maxilliped, which range from 0.6–0.7 in N. auderseti sp. nov. ( Fig. 2C ), compared to 0.5–0.7 in N. niceforoi ( Campos 1994: fig. 34e, fig. 37a–c). Additionally, in N. auderseti sp. nov. the orifice of the efferent branchial channel ( Fig. 2B ) is subquadrate, and presents three spinules on superior angle of lateral lobe of the epistome, while in N. niceforoi , the orifice is ovate ( Campos 1994: fig. 37d–f).

Geographical distribution of Neostrengeria species. The newly described species expand our knowledge of the genus Neostrengeria , which now encompasses 28 species distributed along the slopes and high plains of Colombia’s Eastern Cordillera (3°– 9°45' N and 72°– 74°30' W) ( Fig. 6 ). This mountain range, shaped by complex marine sedimentation within deep basins and subsequent orogenic processes, is a product of the northwestern South American plate’s convergent margin. Its formation involved the interplay of powerful marine sediment banks, ancient massifs, tertiary volcanoes, and igneous-metamorphic cores ( Forero-Suarez 1990; Chicangana & Kammer 2013).

The distribution of Neostrengeria spans from La Jagua de Ibirico (Cesar Department) in the north to Támara (Casanare Department) in the west, and the Serrania de la Macarena (Meta Department) in the south ( Fig. 6 ), with altitude range of 300 to 3200m above sea level ( Table 1).

Neostrengeria auderseti sp. nov. 1790

Neostrengeria bataensis Campos & Pedraza, 2008 540–1660

Neostrengeria binderi Campos, 2000 470–1100

Neostrengeria botti Rodríguez & Türkay, 1978 1350 –2600

Neostrengeria boyacensis Rodríguez, 1980 2350–3200

Neostrengeria celioi Campos & Pedraza, 2008 300–1570

Neostrengeria charalensis Campos & Rodríguez, 1985 1450–2450

Neostrengeria fernandezi Campos, 2017 2000

Neostrengeria gilberti Campos, 1992 720–1800

Neostrengeria guenteri ( Pretzmann, 1965) 450 –1600

Neostrengeria lasallei Rodríguez, 1980 600–2150

Neostrengeria lassoi Campos, 2017 1560

Neostrengeria lemaitrei Campos, 2004 720

Neostrengeria libradensis Rodríguez, 1980 1200

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The formation of the Eastern Cordillera resulted in a diverse array of environments, encompassing longitudinal and transverse valleys, slopes, highlands, moorlands, and foothills. These environments vary significantly in altitude and local ecological conditions. To classify the species, we will now categorize them based on these environments ( Fig. 6 ) and the morphology of the first male gonopod.

Figures

FIGURE 1. Neostrengeria auderseti sp. nov., male holotype (CL 17.0 mm, CW 29.4 mm) (ICN-CR 3720). A, overall dorsal view; B, overall ventral view.

FIGURE 2. Neostrengeria auderseti sp. nov., male holotype (CL 17.0 mm, CW 29.4 mm) (ICN-CR 3720). A, frontal view of carapace; B, opening of left efferent branchial channel, external view; C, left third maxilliped, external view; D, chela of large cheliped, external view.

FIGURE 3. Neostrengeria auderseti sp. nov., male holotype, ICN-CR 3720. A, left first gonopod, ventral view; B, same, mesial view; C, same, lateral view; D, same, dorsal view; E, apex distal view. The numbers in the figures refers to: 1 = marginal suture; 2 = lateral lobe; 3 = accessory lobe; 4 = basal expansion; 5 = ventro-lateral expansion; 6 = notch between lateral and accessory lobes; 7 = mesial lobe; 8 = dorsal spine; 9 = spermatic channel; 10 = meso-ventral projection of spermatic channel.

FIGURE 4. Colour in life of Neostrengeria auderseti sp. nov., male holotype, (CL 17.0 mm, CW 29.4 mm) (ICN-CR 3720).

FIGURE 5. Photograph of El Nitro Cave. La Aguada Municipality, Santander Department where the species was collected.

FIGURE 6. Map of the Eastern Cordillera, Colombia, showing the distribution of the species of Neostrengeria: 1, Neostrengeria alexae Campos, 2010; 2, N. appressa Campos, 1992; 3, N. aspera Campos, 1992; 4, N. auderseti sp. nov.; 5, N. bataensis Campos & Pedraza, 2008; 6, N. binderi Campos, 2000; 7, N. botti Rodríguez & Türkay, 1978; 8, N. boyacensis Rodríguez, 1980; 9, N. celioi Campos & Pedraza, 2008; 10, N. charalensis Campos & Rodríguez, 1985; 11, N. fernandezi Campos, 2017; 12, N. gilberti Campos, 1992; 13, N. guenteri (Pretzmann, 1965); 14, N. lasallei Rodríguez, 1980; 15, N. lassoi Campos, 2017; 16, N. lemaitrei Campos, 2004; 17, N. libradensis Rodríguez, 1980; 18, N. lindigiana (Rathbun, 1897); 19, N. lobulata Campos, 1992; 20, N. macarenae Campos, 1992; 21, N. macropa (H. Milne Edwards, 1853); 22, N. monterrodendoensis (Bott, 1967); 23, N. natashae Campos, 2011; 24, N. niceforoi (Schmitt, 1969); 25, N. perijaensis Campos & Lemaitre, 1998; 26, N. sketi Rodríguez, 1985; 27, N. tencalanensis Campos, 1992; 28, N. tonensis Campos, 1992. Black points indicate localities; overlapped areas indicate sympatric regions.