Longipotamonautes bolobo, Cumberlidge & Krajenka, 2023

Cumberlidge, Neil & Krajenka, Grace E., 2023, Description of two new species of Central African freshwater crabs from the Democratic Republic of the Congo and Rwanda (Brachyura: Potamoidea: Potamonautidae), Zootaxa 5293 (2), pp. 379-391 : 380-385

publication ID	https://doi.org/ 10.11646/zootaxa.5293.2.11
publication LSID	lsid:zoobank.org:pub:B8EA1F62-A17B-445D-A388-8C66FAE4F3D5
DOI	https://doi.org/10.5281/zenodo.7971679
persistent identifier	https://treatment.plazi.org/id/03D787B4-FB4A-EA70-FF6E-FCB0FC76FE5C
treatment provided by	Plazi
scientific name	Longipotamonautes bolobo
status	sp. nov.

Treatment

Longipotamonautes bolobo View in CoL n. sp.

( Figs. 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 , 7 View FIGURE7 )

Holotype. RMCA _ CRUST _50940, adult male ( CW 38.8 , CL 27.8, CH 13.4, FW 13.2 mm; length of propodus of major chela = 41.7 mm); Democratic Republic of the Congo, Bulobo (= Bolobo) (2.168828°S, 16.225909°E), 1959, coll. N. Kele. GoogleMaps

Diagnosis. Carapace surface smooth, widest in anterior third (CW/FW = 2.9), medium height ( CH /FW 1.01) ( Fig. 1B View FIGURE 1 ), semi-circular, urogastric, cardiac, transverse branchial grooves, posterior grooves deep; cervical grooves short, faint ( Fig. 1A View FIGURE 1 ); frontal width about 1/3 carapace width (FW/CW = 0.34); frontal margin straight ( Fig. 1A, B View FIGURE 1 ); exorbital tooth small, pointed, directed forward; epibranchial tooth reduced to granule; postfrontal crest sharply defined, complete, traversing entire carapace; straight part consisting of fused epigastric, postorbital crests; meeting carapace lateral margins at epibranchial teeth; carapace lateral margin posterior to epibranchial tooth smooth ( Fig. 1A, B View FIGURE 1 ). Branchiostegite with longitudinal (epimeral), vertical sutures, dividing carapace sidewall into suborbital, subhepatic, pterygostomial regions, each with smooth surface ( Fig. 1B View FIGURE 1 ); pterygostomial region divided into two parts by additional sulcus continuous with vertical sulcus reaching down to third maxilliped basis ( Fig. 1B View FIGURE 1 ). S3/4 complete, deep, U-shaped, middle meeting anterior margin of sternopleonal cavity; outer margins of S4 low, not raised ( Fig. 1B View FIGURE 1 ). Third maxilliped ischium smooth, vertical sulcus very faint ( Fig. 1B View FIGURE 1 ). Major cheliped propodus elongated, inferior margin length (41.7 mm) greater than CW (38.8 mm). Movable finger (dactylus) of right chela slim, distinctly arched, enclosing broad oval interspace when closed; dactylus with two large rounded teeth proximally with two small teeth in between, distal half with small even-sized teeth; fixed finger (pollex of propodus) of right chela with two very large rounded teeth proximally, distal half with small even-sized teeth ( Fig. 2B, C View FIGURE 2 ). Distal tooth on cheliped carpus inner margin large, slim, pointed, proximal tooth reduced to granule, followed by series of granules along margin ( Fig. 2F View FIGURE 2 ). Cheliped merus lower margins both completely smooth, distal meral tooth obscure ( Fig. 2D View FIGURE 2 ). Telson bell-shaped with deeply indented side margins, apex rounded. G1 TA short (G1 TA/SA = 0.33), basal half angled slightly outward at 50 ° to longitudinal axis of G1 SA, distal 1/3 curved upwards, tapering to pointed tip; G1 TA slim, not widened in midsection ( Fig. 3A, B View FIGURE 3 ); longitudinal groove of G1 TA visible along proximal 2/3. G2 TA long, flagellum-like (G2 TA/SA = 0.5) ( Fig. 3C View FIGURE 3 ).

Description. Male holotype. Carapace with moderate width (CW/FW = 2.9), length (CL/ FW 2.1), height ( CH / FW = 1.01); carapace surface smooth, semi-circular, urogastric, cardiac, transverse branchial grooves, posterior grooves deep; cervical grooves short, faint ( Fig. 1A View FIGURE 1 ). Front width about 1/3 carapace width (FW/CW = 0.34); frontal margin straight ( Fig. 1A, B View FIGURE 1 ); exorbital tooth small, pointed, directed forward; epibranchial tooth reduced to granule; epigastric crests low, separated by clear, short, forked mid-groove; postfrontal crest sharply defined, complete, traversing entire carapace; straight part consisting of fused epigastric, postorbital crests; meeting carapace lateral margins at epibranchial teeth; carapace lateral margin posterior to epibranchial tooth smooth ( Fig. 1A, B View FIGURE 1 ). Branchiostegite with longitudinal (epimeral), vertical sulci, dividing carapace sidewall into suborbital, subhepatic, pterygostomial regions, each with smooth surface ( Fig. 1B View FIGURE 1 ), pterygostomial region divided into two parts by additional sulcus continuous with vertical sulcus reaching down to third maxilliped basis ( Fig. 1B View FIGURE 1 ).

Mandibular palp consisting of basis followed by 2 articles; terminal article simple.

Third maxillipeds filling entire oral field, except for transversely oval efferent respiratory openings. Ischium smooth, vertical sulcus very faint ( Fig. 1B View FIGURE 1 ). Exopod with long flagellum, ischium vertical sulcus faint ( Fig. 1B View FIGURE 1 ).

Thoracic sternal sutures S1/2, S2/3 deep, completely traversing sternum; S3/4 complete, deep, U-shaped, middle meeting anterior margin of sternopleonal cavity; outer margins of S4 low, not raised ( Fig. 1B View FIGURE 1 ); episternal sulci S4/E4, S5/E5, S6/ E6, S7/E7 each distinct.

Chelipeds unequal, right (major) longer, higher than left (minor) ( Fig. 2B, C View FIGURE 2 ). Major chela propodus inferior margin length (41.7 mm) greater than CW (38.8 mm). Movable finger (dactylus) of right chela slim, distinctly arched, tips touching when closed, enclosing broad oval interspace; propodus palm swollen. Dactylus proximal half with two large, rounded teeth, two small teeth in between, distal half with small even-sized teeth; fixed finger (pollex of propodus) of right chela with two very large, rounded teeth proximally, distal half with small even-sized teeth ( Fig. 2B, C View FIGURE 2 ). Distal tooth on cheliped carpus inner margin large, slim, pointed, proximal tooth reduced to granule followed by series of granules along margin ( Fig. 2F View FIGURE 2 ). Cheliped merus lower margins both completely smooth, distal meral tooth obscure ( Fig. 2D View FIGURE 2 ).

Ambulatory legs (P2–5) slender, P5 shortest; dactyli P2–5 tapering to point, each bearing rows of downwardpointing sharp bristles ( Fig. 1A View FIGURE 1 ).

Male pleon, telson together forming triangle with convex margins, broadest at base; telson bell-shaped with deeply indented side margins, apex rounded; pleomeres PL1–6 rectangular, wider than long, PL 6 longest, more than 1/2 as long as wide ( Fig. 1B View FIGURE 1 ); remaining pleomeres short, more than 1/4 as long as wide. G1 TA short (G1 TA/SA = 0.33), basal half angled outward at 50 ° to longitudinal axis of G1 SA, distal 1/3 curved upwards, tapering to pointed tip; G1 TA slim, not widened in midsection ( Fig. 3A, B View FIGURE 3 ); longitudinal groove of G1 TA visible along proximal 2/3. G1 SA widest at base, narrowest at G1 TA/SA junction; G1 SA ventral side mesial margins with tuft of conspicuous long setae; lateral margin with short sparse setae; G1 SA ventral side with broad setae-lined fold partly covering SA basally, completely covering SA at TA-SA junction; G1 SA dorsal side with broad dorsal membrane at TA-SA junction. G2 SA widest at base, tapering sharply inward about 1/3 along length, distal 2/3s forming long, thin, tapering, upright process supporting long, flagellum-like G2 TA (G2 TA/SA = 0.33) ( Fig. 3C View FIGURE 3 ). Medium-sized species, adult at CW 38.8 mm.

Colour. The colour of living specimens is unknown, but the specimen preserved in ethanol is light brown.

Type locality. Democratic Republic of the Congo, Bolobo (= Bulobo), on the Congo River in Mai-Ndombe Province GoogleMaps (2.168828°S, 16.225909°E), 281.33 m ASL ( Fig. 7 View FIGURE7 ).

Etymology. The species is named for Bolobo, which is a town on the Congo River in Mai-Ndombe Province in the western part of the D. R. Congo where it was collected. The species epithet is used as a noun in apposition.

. Distribution. Longipotamonautes bolobo n. sp. is known only from just one locality on the Congo River (2.168828°S, 16.225909°E) 281.3 m ASL, in Mai-Ndombe Province GoogleMaps in the D. R. Congo ( Fig. 7 View FIGURE7 ).

Habitat. Bolobo lies in the Kasai Ecoregion ( FEOW 546 ) in the catchment of the Kasai River , which occupies a vast area (900,000 km 2) within southwestern D. R. Congo and the northeast corner of Angola. The type locality is in the low-lying central Congo basin (the Cuvette Centrale).

Conservation status. Very little information is available on the distributional range, population size and trends, or habitat of L. bolobo n. sp. which is considered here as Data Deficient until more field data can be collected.

Remarks. The genus Longipotamonautes ( Bott, 1955) currently comprises nine species from the D. R. Congo, the Republic of the Congo, Gabon, Cameroon, and Nigeria ( Cumberlidge & Daniels 2022). Longipotamonautes bolobo n. sp. is assigned to this genus because it conforms to the diagnosis provided by Cumberlidge & Daniels (2022: 1291). For example, L. bolobo n. sp. has a third maxilliped whose ischium is smooth and lacks a distinct vertical sulcus; the G1 TA is medium long (G1 TA length 0.33 × G1 SA length) and slim, with low medial and low lateral folds and a blunt (not pointed) tip ( Fig. 1A, B View FIGURE 1 ); the telson is bell-shaped with indented lateral margins; the pleon is broadly triangular, with subequal sides and base; the lower margin of the major chela propodus is longer than the carapace width; and the major chela dactylus is slim and highly arched ( Fig. 1D–F View FIGURE 1 ).

Longipotamonautes bolobo n. sp. is closest to L. acristatus (Bott, 1995) and L. adentatus ( Bott, 1955) in that the epibranchial tooth is reduced to a granule, the carapace lateral margins are smooth ( Fig. 1A View FIGURE 1 ), and the adult male major cheliped is longer than the CW in all three species ( Fig. 2A View FIGURE 2 ). In addition, the holotype of L. acristatus (as Potamonautes (Longipotamonautes) ballayi acristatus (RMCA_CRUST_32018)) was also collected from Bolobo, D. R. Congo ( Bott 1955). Longipotamonautes bolobo n. sp. can be distinguished from L. acristatus and L. adentatus by the exorbital tooth, which is distinct and pointed in L. bolobo n. sp. ( Fig. 1A View FIGURE 1 ) (vs a low or absent exorbital tooth in L. acristatus ( Bott 1955: pl. VIII, fig. 2a; fig. 75) and L. adentatus ( Bott 1955: pl. VIII, fig. 1a; fig. 74)), and by the dentition on the major chela, where the movable and fixed fingers each have two large teeth spaced apart on the cutting edges in L. bolobo n. sp. ( Fig. 2A View FIGURE 2 ) (vs a major chela whose movable and fixed fingers lack teeth in L. acristatus ( Bott 1955: pl. VIII, fig. 2a; fig. 75) and L. adentatus ( Bott 1955: pl. VIII, fig. 1a; fig. 74)). In addition, the size at maturity is different in these species: L. bolobo n. sp. is adult at CW 38.8 mm, whereas both L. acristatus and L. adentatus are adult at CW 29 mm. Longipotamonautes bolobo n. sp. can be further distinguished from L. adentatus by the strong distinct postfrontal crest (vs a weak and poorly defined postfrontal crest in L. adentatus ).

Longipotamonautes bolobo n. sp. can be distinguished from the seven other species in this genus as follows. The epibranchial tooth is lacking and the carapace lateral margin is smooth and lacks teeth in L. bolobo n. sp. ( Fig. 1A View FIGURE 1 ) (vs a large pointed epibranchial tooth and a carapace lateral margin that has two teeth behind the epibranchial tooth in L. nheenae Cumberlidge, 2017 from Gabon ( Cumberlidge 2017: fig. 1A, 4B), a large pointed epibranchial tooth and a carapace lateral margin that has three teeth behind the epibranchial tooth in L. paecilei (A. Milne-Edwards, 1886) from the D. R. Congo ( Bott 1955; Cumberlidge 2017); a large pointed epibranchial tooth and a carapace lateral margin that has one tooth behind the epibranchial tooth in both L. schubotzi ( Balss, 1936) from the D. R. Congo and L. reidi ( Cumberlidge, 1999) from Nigeria and Cameroon ( Bott 1955; Cumberlidge 1999: 15 D, 2017); and a large pointed epibranchial tooth and a carapace lateral margin that is smooth and lacks teeth behind the epibranchial tooth in L. ballayi (A. Milne-Edwards, 1886)) .

Longipotamonautes bolobo n. sp. can be distinguished from L. punctatus ( Bott, 1955) by the lack of a proximal tooth on the cheliped carpus inner margin ( Fig. 2F View FIGURE 2 ) (vs a small acute proximal tooth on the cheliped carpus inner margin in L. punctatus ( Bott 1955: fig. 72). Finally, L. bolobo n. sp. can be distinguished from L. semilunaris ( Bott, 1955) by the deep S3/4 that completely traverses the sternum and meets the anterior margin of the sternopleonal cavity, and by the outer margins of S4 that are low and not raised ( Fig. 1B View FIGURE 1 ) (vs an incomplete S3/4 that is deep only at the margins and faint in the middle and does not meet the anterior margin of the sternopleonal cavity, and outer margins of S4 that are raised in L. semilunaris ( Bott 1955: pl. XXIV fig. 2b)).