Saved in:
| Main Authors: | , , |
|---|---|
| Format: | Recurso digital |
| Language: | |
| Published: |
Zenodo
2025
|
| Subjects: | |
| Online Access: | https://doi.org/10.5281/zenodo.16739563 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1866901991894024192 |
|---|---|
| author | Cumberlidge, Neil Huiskens, Alyssa J. Jonas, Gabrielle I. |
| author_facet | Cumberlidge, Neil Huiskens, Alyssa J. Jonas, Gabrielle I. |
| contents | <p><b><i>Arcopotamonautes unisulcatus</i> (Rathbun, 1933)</b></p><p>(Figures 1–5, 10)</p><p><i>Potamon</i> (<i>Potamonautes</i>) <i>johnstoni unisulcatus</i> Rathbun, 1933: 255, pl. 2, figs. 2–4.</p><p><i>Potamon unisulcatus</i> — Chace 1942: 223.</p><p><i>Potamonautes</i> (<i>Lirrangopotamonautes</i>) <i>johnstoni johnstoni</i> <i>—</i> Bott 1955: 265–267, pl. XV, fig. 2a–d, fig. 36a, b.</p><p><i>Potamonautes unisulcatus —</i> Reed & Cumberlidge 2006: 3–5, 11, 15, 23, 37, 38, 58–60, pl. XIII, figs. A–D, table 1–4, figs. 124–133, 169,170, 185, appendix.—Ng <i>et al</i>. 2008: 171.</p><p><i>Arcopotamonautes unisulcatus —</i> Cumberlidge & Daniels 2022: 1274, 1294.</p><p><b>Type material.</b> Holotype: MCZ CRU-7678, adult female (CW 52.0 mm, CL 35.0 mm), Tanzania, Uluguru Mountains, Bagilo (-7.105079, 37.654157, 1,935m ASL), coll. A. Loveridge, September 1926. Paratypes: MCZ CRU-7678a, adult male (CW 33.0 mm, CL 21.0 mm), same data as holotype. – MCZ CRU-7678b, 3 adult males (no measurements available), 2 adult females (no measurements available), same data as holotype.</p><p><b>Other material examined:</b> NMU TRWEA62.45, subadult male (CW 31.6 mm), subadult female (CW 41.1 mm), 2 juvs. (CWs 17.1, 16.3 mm), Tanzania, Uluguru Mountains, Bunduki, Kitange-Tange River, tributary of Mgeta River 2.4–3.0 m wide, near Hululu Waterfalls Mgeta (-7.049021, 37.642489, 1,603 m ASL), riverbed with large boulders, gravel, stones and sand, coll. T. R. Williams, 23 February 1962. – NMU TRWEA62.47, 2 subadult males (CWs 29.8, 27.0 mm), 4 juvs. (CWs 15.6 mm, 15.9 mm, 16.2 mm, 17.8 mm), Tanzania, Uluguru Mountains, Bunduki rest house, Kitange-Tange River, 1859–1890 m ASL, river falling rapidly over large boulders, with gravel flats and occasional large stones, coll. T. R. Williams, 23 February 1962. – NMU TRWEA62.49 (illustrated), adult male (CW 33.6 mm, CL 23.4 mm, CH 11.1 mm, FW 10.6 mm), adult female ovigerous (CW 28.3 mm), Tanzania, Bunduki, Uluguru Mountains, from small, shaded stream near forest margin, coll. T. R. Williams, 23 February 1962.</p><p><b>Diagnosis.</b> Postfrontal crest sharp-edged, completely crossing carapace; exorbital tooth low but distinct, epibranchial tooth reduced to small granule; (Fig. 1A, B); anterolateral, lateral carapace margins distinctly granulated; carapace branchiostegite smooth; third maxilliped ischium lacking vertical sulcus; S3/4 incomplete, deep at sides, obscure in middle; thoracic episternal sulci S4/E4, S5/E5 deep, complete, S6/E6, S7/E7 obscure (Fig. 2B, C). Male right (major) chela dactylus straight, not arched, broad, cutting edge lined by large teeth, largest proximally, becoming smaller distally; cheliped merus stout, anterior inferior margin lined by small teeth, distal meral tooth large, posterior inferior margin smooth (Fig. 3C, D); cheliped carpus inner margin distal tooth medium sized pointed, proximal tooth small, pointed, followed by two granules (Fig. 3E); G1TA about 1/3 G1SA length (G1TA/G1SA 0.4), basal half straight, distal half curved outward at 45° to longitudinal axis of G1SA; G1TA tapering to pointed straight tip, mid-section widened by additional rounded crest on dorsal lobe with distinct setae on ventral lobe; G1TA dorsal, ventral lobes separated in middle by long groove (Figs. 4A–C, 5B, C).</p><p><b>Description.</b> Carapace surface smooth, widest in anterior third (CW/FW 3.1), medium height (CH /FW 1.1) (Figs. 1A, B, 2A), semi-circular, urogastric grooves deep; cardiac region weakly marked, cervical grooves short, faint; transverse branchial grooves faint (Fig. 1A, B). Front about 1/3 carapace width (FW/CW 0.3); frontal margin straight (Figs. 1A, B, 2A); exorbital tooth small, blunt; epibranchial tooth reduced to granule; postfrontal crest sharply defined, complete, traversing entire carapace; lateral carapace margin posterior to epibranchial tooth granulated (Fig. 1A, B). Branchiostegite with two sutures, one longitudinal (epimeral), one vertical, dividing carapace sidewall into suborbital, subhepatic, pterygostomial regions, all smooth (Fig. 3A).</p><p>Third maxillipeds filling entire oral field, except for transversely oval efferent respiratory openings at superior lateral corners, exopod with long flagellum, endopod ischium smooth (Fig. 2D). Mandibular palp consisting of basis plus two articles; terminal article simple, undivided, lacking lobe or ridge at junction between articles (Fig. 2E). Anterior, posterior male thoracic sternum surface completely smooth; sternal sulci S1/2, S2/3 completely traversing sternum; S3/4 incomplete, deep at sides, obscure in middle; thoracic episternal sulci S4/E4, S5/E5 deep, complete, S6/E6, S7/E7 obscure (Fig. 2B, C).</p><p>Male right (major) chela dactylus straight, not arched, broad, cutting edge lined by large teeth, largest proximally, becoming smaller distally; immovable finger (propodus pollex) broad, cutting edge lined by large teeth, largest proximally, becoming smaller distally; tips of both fingers touching when chela closed, enclosing long narrow interspace; major chela propodus palm enlarged, swollen, lower margin curving downward, distinctly convex, cutting edge toothed, largest teeth proximally, becoming smaller distally (Fig. 3A). Male left (minor) chela dactylus slim, gently curved, cutting edge with large teeth proximally, small teeth distally; propodus pollex cutting edge lined by large teeth, largest proximally, becoming smaller distally; tips of both fingers touching when chela closed, enclosing long narrow interspace; minor chela propodus palm subequal to that of major chela; lower margin gently curved, convex (Fig. 3B). Cheliped merus stout, anterior inferior margin lined by small teeth, distal meral tooth large, posterior inferior margin smooth (Fig. 3C, D); cheliped carpus inner margin distal tooth medium sized, pointed; proximal tooth small, pointed, followed by two granules (Fig. 3E); ambulatory legs P2–5 stout, distal limb articles (merus, carpus, propodus, dactylus) not elongated; dactyli of P2–5 tapering to point, each bearing four rows of downward-pointing sharp bristles (Fig. 1A). Male pleon, telson together forming slim triangle; pleon edges slightly indented; telson triangular, apex rounded, base broadest, sides outwardly sloping; pleomeres PL1–6 rectangular, wider than long, PL 6 longest, more than 1/2 as long as wide; remaining pleomeres short, less than 1/3 as long as wide (Fig. 2B, C).</p><p>G1TA about 1/3 G1SA length (G1TA/G1SA 0.4), basal half straight, distal half curved outward at 45° to longitudinal axis of G1SA; G1TA with setae on lateral margin, rounded crest in midsection, distal third tapering to pointed straight tip; G1TA dorsal lobe low, ventral lobe low widened by additional rounded crest in mid-section which has long setae; lobes separated in middle by thin groove (Fig. 4A–C, 5B, C). G1SA widest at base, narrowest at G1TA-G1SA junction; G1SA mesial, lateral margins lined by long setae (Fig. 4A, 5B). G2SA (Fig. 5A) long, slim, subequal to G1SA; G2SA widest at base, tapering sharply inward about one-third along length, last 2/3rds forming long, thin, tapering, upright process supporting long flagellum-like G2TA (G2TA/G2SA 0.5) (Fig. 5A).</p><p><b>Size.</b> Medium-sized species, the adult size range is between CW 33.0–52.0 mm.</p><p><b>Type locality.</b> Tanzania, Uluguru Mountains, Bagilo.</p><p><b>Colour.</b> Living male specimens have a purple-pink carapace and paler walking legs. Carapace of living female distinctly mottled with darker areas. Specimens preserved in ethanol are light brown.</p><p><b>Habitat.</b> At Bunduki in the Uluguru Mountains this species is most abundant either near, or within, higher altitude forest and occurs only rarely at lower altitudes. Crabs were collected from a small shaded stream near the forest margin.</p><p><b>Distribution.</b> Endemic to the Uluguru Mountains, Tanzania, East Africa (Fig. 10).</p><p><b>Conservation status.</b> <i>Arcopotamonautes unisulcatus</i> is currently assessed as vulnerable because it is only known from two locations, has a restricted extent of occurrence, less than 20,000 km ²), and a small area of occupancy that are both below the thresholds for vulnerable (IUCN 2004). In addition, its distribution is fragmented, and it is threatened by a continuing decline in the extent and quality of its habitat due to degradation driven by human population increases and industrial and agrarian development, and <i>A. unisulcatus</i> is not found in a protected area.</p><p><b>Remarks.</b> Bott (1955) treated <i>Potamon</i> (<i>Potamonautes</i>) <i>unisulcatus</i> Rathbun, 1933 as a junior synonym of <i>A. johnstoni</i> (Miers, 1885). The present study, however, agrees with the opinion of Reed & Cumberlidge (2006) that both of these taxa are each valid species. <i>Arcopotamonautes unisulcatus</i> is redescribed here because the earlier redescription of this species by Reed & Cumberlidge (2006) provided only a brief account and did not make comparisons with other species. In addition, the earlier descriptions have been expanded by adding new taxonomic characters such as mandibles and gonopods that were not previously described. Furthermore, this species is also compared with similar newly-described taxa from the region.</p><p><b>Comparisons.</b> <i>Arcopotamonautes</i> (Bott, 1955) currently comprises 18 species from the D.R. Congo, Kenya, Malawi, Rwanda, Tanzania, and Zambia (Reed & Cumberlidge 2006; Cumberlidge & Daniels 2022; Cumberlidge & Jonas 2024; Cumberlidge & Conners 2025). <i>Arcopotamonautes unisulcatus</i> can be distinguished from <i>A. suprasulcatus</i> (Hilgendorf, 1898), <i>A. xiphoidus</i> (Reed & Cumberlidge, 2006), <i>A. infravallatus</i> (Hilgendorf, 1898), and <i>A. bellarussus</i> (Daniels, Phiri & Bayliss, 2014) by the form of the G1TA, which is distinctly widened in the midsection in <i>A. unisulcatus</i> (Figs. 4A–C, 5A, C, 9A–C, 10B, C) (versus slim, curved, and needle-like in <i>A. suprasulcatus</i> and <i>A. bellarussus</i> (Daniels <i>et al</i>. 2014: fig, 5A, B), or cone-shaped, not widened, and tapering to a pointed tip in both <i>A. xiphoidus</i> (Fig. 9A, B) and <i>A. infravallatus</i>; Cumberlidge & Conners 2025: figs. 1A, B, D, 6E). <i>Arcopotamonautes unisulcatus</i> can be distinguished from <i>A. orbitospinus</i> (Cunnington, 1907) from Lake Malawi and <i>A. platynotus</i> (Cunnington, 1907) from Lake Tanganyika by the form of the carapace lateral margin which is granular in <i>A. unisulcatus</i> (Figs. 1A, B, 6A, B) (versus a lateral margin that has several teeth behind the epibranchial tooth in <i>A. orbitospinus</i> (Reed & Cumberlidge 2006: pl. V, A, B; fig. 42 as <i>Potamonautes lirrangensis</i>), and <i>A. platynotus</i>; Reed & Cumberlidge 2006: fig. 94). <i>Arcopotamonautes unisulcatus</i> can be distinguished from <i>A. platycentron</i> (Hilgendorf, 1897) from Lake Chala (Kenya and Tanzania) by the form of the cheliped carpus distal tooth, which is slim and pointed in <i>A. unisulcatus</i> (Figs. 3C, 8E) (versus extremely broad, flat and blunt in <i>A. platycentron</i>; Reed & Cumberlidge 2006: figs. pl. IX, A).</p><p><i>Arcopotamonautes unisulcatus</i> can be distinguished from <i>A. amosae</i> (Cumberlidge, Johnson, Clark & Genner, 2021), <i>A. caputanatis</i> Cumberlidge, Clark & Fastiggi, 2019), <i>A. johnstoni</i> (Miers, 1885), <i>A. raybouldi</i> (Cumberlidge & Vannini, 2004), <i>A. gerdalensis</i> (Bott, 1955) and <i>A. montivagus</i> (Chace, 1953) by the form of the G1TA, which has a rounded low crest arising out of the dorsal lobe in <i>A. unisulcatus</i> (Figs. 4A–C, 5A, C, 9A–C, 10B, C) (versus a G1TA, where a high thin crest arises from the dorsal lobe in <i>A. amosae</i>, <i>A. caputanatis</i>, <i>A. johnstoni</i> (Reed & Cumberlidge 2006: figs. 151, 152), <i>A. raybouldi</i> (Reed & Cumberlidge 2006: figs. 165, 166), <i>A. gerdalensis</i> (Reed & Cumberlidge 2006: figs. 147, 148), and <i>A. montivagus</i>; Chace 1953: fig. 3e–g, j). <i>Arcopotamonautes unisulcatus</i> can be distinguished from <i>A. parekeeae</i> Cumberlidge & Jonas, 1924 and <i>A. ngae</i> Cumberlidge & Jonas, 1924 by the sulci on the anterior thoracic sternum, where the S3/4 is missing except for two short notches at the margins in <i>A. unisulcatus</i> (versus deep and completely traversing the thoracic sternum in <i>A. parekeeae</i> and <i>A. ngae</i> (Cumberlidge & Jonas, 1924: figs. 2B, C, 7B, C)). Finally, <i>A. unisulcatus</i> can be distinguished from <i>A. picus</i> Cumberlidge & Conners, 2025 by the form of the G1TA, which is distinctly widened in the midsection in <i>A. unisulcatus</i> (Figs. 4A– C, 5A, C, 9A–C, 10B, C) (versus slim and tapering to a slightly upcurved tip in <i>A. picus</i>; Cumberlidge & Conners 2025: fig. 4A, B, D–F).</p> |
| format | Recurso digital |
| id | zenodo_https___doi_org_10_5281_zenodo_16739563 |
| institution | Zenodo |
| language | |
| publishDate | 2025 |
| publisher | Zenodo |
| record_format | zenodo |
| spellingShingle | Arcopotamonautes unisulcatus Cumberlidge, Neil Huiskens, Alyssa J. Jonas, Gabrielle I. Biodiversity Taxonomy Animalia Arthropoda Malacostraca Decapoda Potamonautidae Arcopotamonautes Arcopotamonautes unisulcatus <p><b><i>Arcopotamonautes unisulcatus</i> (Rathbun, 1933)</b></p><p>(Figures 1–5, 10)</p><p><i>Potamon</i> (<i>Potamonautes</i>) <i>johnstoni unisulcatus</i> Rathbun, 1933: 255, pl. 2, figs. 2–4.</p><p><i>Potamon unisulcatus</i> — Chace 1942: 223.</p><p><i>Potamonautes</i> (<i>Lirrangopotamonautes</i>) <i>johnstoni johnstoni</i> <i>—</i> Bott 1955: 265–267, pl. XV, fig. 2a–d, fig. 36a, b.</p><p><i>Potamonautes unisulcatus —</i> Reed & Cumberlidge 2006: 3–5, 11, 15, 23, 37, 38, 58–60, pl. XIII, figs. A–D, table 1–4, figs. 124–133, 169,170, 185, appendix.—Ng <i>et al</i>. 2008: 171.</p><p><i>Arcopotamonautes unisulcatus —</i> Cumberlidge & Daniels 2022: 1274, 1294.</p><p><b>Type material.</b> Holotype: MCZ CRU-7678, adult female (CW 52.0 mm, CL 35.0 mm), Tanzania, Uluguru Mountains, Bagilo (-7.105079, 37.654157, 1,935m ASL), coll. A. Loveridge, September 1926. Paratypes: MCZ CRU-7678a, adult male (CW 33.0 mm, CL 21.0 mm), same data as holotype. – MCZ CRU-7678b, 3 adult males (no measurements available), 2 adult females (no measurements available), same data as holotype.</p><p><b>Other material examined:</b> NMU TRWEA62.45, subadult male (CW 31.6 mm), subadult female (CW 41.1 mm), 2 juvs. (CWs 17.1, 16.3 mm), Tanzania, Uluguru Mountains, Bunduki, Kitange-Tange River, tributary of Mgeta River 2.4–3.0 m wide, near Hululu Waterfalls Mgeta (-7.049021, 37.642489, 1,603 m ASL), riverbed with large boulders, gravel, stones and sand, coll. T. R. Williams, 23 February 1962. – NMU TRWEA62.47, 2 subadult males (CWs 29.8, 27.0 mm), 4 juvs. (CWs 15.6 mm, 15.9 mm, 16.2 mm, 17.8 mm), Tanzania, Uluguru Mountains, Bunduki rest house, Kitange-Tange River, 1859–1890 m ASL, river falling rapidly over large boulders, with gravel flats and occasional large stones, coll. T. R. Williams, 23 February 1962. – NMU TRWEA62.49 (illustrated), adult male (CW 33.6 mm, CL 23.4 mm, CH 11.1 mm, FW 10.6 mm), adult female ovigerous (CW 28.3 mm), Tanzania, Bunduki, Uluguru Mountains, from small, shaded stream near forest margin, coll. T. R. Williams, 23 February 1962.</p><p><b>Diagnosis.</b> Postfrontal crest sharp-edged, completely crossing carapace; exorbital tooth low but distinct, epibranchial tooth reduced to small granule; (Fig. 1A, B); anterolateral, lateral carapace margins distinctly granulated; carapace branchiostegite smooth; third maxilliped ischium lacking vertical sulcus; S3/4 incomplete, deep at sides, obscure in middle; thoracic episternal sulci S4/E4, S5/E5 deep, complete, S6/E6, S7/E7 obscure (Fig. 2B, C). Male right (major) chela dactylus straight, not arched, broad, cutting edge lined by large teeth, largest proximally, becoming smaller distally; cheliped merus stout, anterior inferior margin lined by small teeth, distal meral tooth large, posterior inferior margin smooth (Fig. 3C, D); cheliped carpus inner margin distal tooth medium sized pointed, proximal tooth small, pointed, followed by two granules (Fig. 3E); G1TA about 1/3 G1SA length (G1TA/G1SA 0.4), basal half straight, distal half curved outward at 45° to longitudinal axis of G1SA; G1TA tapering to pointed straight tip, mid-section widened by additional rounded crest on dorsal lobe with distinct setae on ventral lobe; G1TA dorsal, ventral lobes separated in middle by long groove (Figs. 4A–C, 5B, C).</p><p><b>Description.</b> Carapace surface smooth, widest in anterior third (CW/FW 3.1), medium height (CH /FW 1.1) (Figs. 1A, B, 2A), semi-circular, urogastric grooves deep; cardiac region weakly marked, cervical grooves short, faint; transverse branchial grooves faint (Fig. 1A, B). Front about 1/3 carapace width (FW/CW 0.3); frontal margin straight (Figs. 1A, B, 2A); exorbital tooth small, blunt; epibranchial tooth reduced to granule; postfrontal crest sharply defined, complete, traversing entire carapace; lateral carapace margin posterior to epibranchial tooth granulated (Fig. 1A, B). Branchiostegite with two sutures, one longitudinal (epimeral), one vertical, dividing carapace sidewall into suborbital, subhepatic, pterygostomial regions, all smooth (Fig. 3A).</p><p>Third maxillipeds filling entire oral field, except for transversely oval efferent respiratory openings at superior lateral corners, exopod with long flagellum, endopod ischium smooth (Fig. 2D). Mandibular palp consisting of basis plus two articles; terminal article simple, undivided, lacking lobe or ridge at junction between articles (Fig. 2E). Anterior, posterior male thoracic sternum surface completely smooth; sternal sulci S1/2, S2/3 completely traversing sternum; S3/4 incomplete, deep at sides, obscure in middle; thoracic episternal sulci S4/E4, S5/E5 deep, complete, S6/E6, S7/E7 obscure (Fig. 2B, C).</p><p>Male right (major) chela dactylus straight, not arched, broad, cutting edge lined by large teeth, largest proximally, becoming smaller distally; immovable finger (propodus pollex) broad, cutting edge lined by large teeth, largest proximally, becoming smaller distally; tips of both fingers touching when chela closed, enclosing long narrow interspace; major chela propodus palm enlarged, swollen, lower margin curving downward, distinctly convex, cutting edge toothed, largest teeth proximally, becoming smaller distally (Fig. 3A). Male left (minor) chela dactylus slim, gently curved, cutting edge with large teeth proximally, small teeth distally; propodus pollex cutting edge lined by large teeth, largest proximally, becoming smaller distally; tips of both fingers touching when chela closed, enclosing long narrow interspace; minor chela propodus palm subequal to that of major chela; lower margin gently curved, convex (Fig. 3B). Cheliped merus stout, anterior inferior margin lined by small teeth, distal meral tooth large, posterior inferior margin smooth (Fig. 3C, D); cheliped carpus inner margin distal tooth medium sized, pointed; proximal tooth small, pointed, followed by two granules (Fig. 3E); ambulatory legs P2–5 stout, distal limb articles (merus, carpus, propodus, dactylus) not elongated; dactyli of P2–5 tapering to point, each bearing four rows of downward-pointing sharp bristles (Fig. 1A). Male pleon, telson together forming slim triangle; pleon edges slightly indented; telson triangular, apex rounded, base broadest, sides outwardly sloping; pleomeres PL1–6 rectangular, wider than long, PL 6 longest, more than 1/2 as long as wide; remaining pleomeres short, less than 1/3 as long as wide (Fig. 2B, C).</p><p>G1TA about 1/3 G1SA length (G1TA/G1SA 0.4), basal half straight, distal half curved outward at 45° to longitudinal axis of G1SA; G1TA with setae on lateral margin, rounded crest in midsection, distal third tapering to pointed straight tip; G1TA dorsal lobe low, ventral lobe low widened by additional rounded crest in mid-section which has long setae; lobes separated in middle by thin groove (Fig. 4A–C, 5B, C). G1SA widest at base, narrowest at G1TA-G1SA junction; G1SA mesial, lateral margins lined by long setae (Fig. 4A, 5B). G2SA (Fig. 5A) long, slim, subequal to G1SA; G2SA widest at base, tapering sharply inward about one-third along length, last 2/3rds forming long, thin, tapering, upright process supporting long flagellum-like G2TA (G2TA/G2SA 0.5) (Fig. 5A).</p><p><b>Size.</b> Medium-sized species, the adult size range is between CW 33.0–52.0 mm.</p><p><b>Type locality.</b> Tanzania, Uluguru Mountains, Bagilo.</p><p><b>Colour.</b> Living male specimens have a purple-pink carapace and paler walking legs. Carapace of living female distinctly mottled with darker areas. Specimens preserved in ethanol are light brown.</p><p><b>Habitat.</b> At Bunduki in the Uluguru Mountains this species is most abundant either near, or within, higher altitude forest and occurs only rarely at lower altitudes. Crabs were collected from a small shaded stream near the forest margin.</p><p><b>Distribution.</b> Endemic to the Uluguru Mountains, Tanzania, East Africa (Fig. 10).</p><p><b>Conservation status.</b> <i>Arcopotamonautes unisulcatus</i> is currently assessed as vulnerable because it is only known from two locations, has a restricted extent of occurrence, less than 20,000 km ²), and a small area of occupancy that are both below the thresholds for vulnerable (IUCN 2004). In addition, its distribution is fragmented, and it is threatened by a continuing decline in the extent and quality of its habitat due to degradation driven by human population increases and industrial and agrarian development, and <i>A. unisulcatus</i> is not found in a protected area.</p><p><b>Remarks.</b> Bott (1955) treated <i>Potamon</i> (<i>Potamonautes</i>) <i>unisulcatus</i> Rathbun, 1933 as a junior synonym of <i>A. johnstoni</i> (Miers, 1885). The present study, however, agrees with the opinion of Reed & Cumberlidge (2006) that both of these taxa are each valid species. <i>Arcopotamonautes unisulcatus</i> is redescribed here because the earlier redescription of this species by Reed & Cumberlidge (2006) provided only a brief account and did not make comparisons with other species. In addition, the earlier descriptions have been expanded by adding new taxonomic characters such as mandibles and gonopods that were not previously described. Furthermore, this species is also compared with similar newly-described taxa from the region.</p><p><b>Comparisons.</b> <i>Arcopotamonautes</i> (Bott, 1955) currently comprises 18 species from the D.R. Congo, Kenya, Malawi, Rwanda, Tanzania, and Zambia (Reed & Cumberlidge 2006; Cumberlidge & Daniels 2022; Cumberlidge & Jonas 2024; Cumberlidge & Conners 2025). <i>Arcopotamonautes unisulcatus</i> can be distinguished from <i>A. suprasulcatus</i> (Hilgendorf, 1898), <i>A. xiphoidus</i> (Reed & Cumberlidge, 2006), <i>A. infravallatus</i> (Hilgendorf, 1898), and <i>A. bellarussus</i> (Daniels, Phiri & Bayliss, 2014) by the form of the G1TA, which is distinctly widened in the midsection in <i>A. unisulcatus</i> (Figs. 4A–C, 5A, C, 9A–C, 10B, C) (versus slim, curved, and needle-like in <i>A. suprasulcatus</i> and <i>A. bellarussus</i> (Daniels <i>et al</i>. 2014: fig, 5A, B), or cone-shaped, not widened, and tapering to a pointed tip in both <i>A. xiphoidus</i> (Fig. 9A, B) and <i>A. infravallatus</i>; Cumberlidge & Conners 2025: figs. 1A, B, D, 6E). <i>Arcopotamonautes unisulcatus</i> can be distinguished from <i>A. orbitospinus</i> (Cunnington, 1907) from Lake Malawi and <i>A. platynotus</i> (Cunnington, 1907) from Lake Tanganyika by the form of the carapace lateral margin which is granular in <i>A. unisulcatus</i> (Figs. 1A, B, 6A, B) (versus a lateral margin that has several teeth behind the epibranchial tooth in <i>A. orbitospinus</i> (Reed & Cumberlidge 2006: pl. V, A, B; fig. 42 as <i>Potamonautes lirrangensis</i>), and <i>A. platynotus</i>; Reed & Cumberlidge 2006: fig. 94). <i>Arcopotamonautes unisulcatus</i> can be distinguished from <i>A. platycentron</i> (Hilgendorf, 1897) from Lake Chala (Kenya and Tanzania) by the form of the cheliped carpus distal tooth, which is slim and pointed in <i>A. unisulcatus</i> (Figs. 3C, 8E) (versus extremely broad, flat and blunt in <i>A. platycentron</i>; Reed & Cumberlidge 2006: figs. pl. IX, A).</p><p><i>Arcopotamonautes unisulcatus</i> can be distinguished from <i>A. amosae</i> (Cumberlidge, Johnson, Clark & Genner, 2021), <i>A. caputanatis</i> Cumberlidge, Clark & Fastiggi, 2019), <i>A. johnstoni</i> (Miers, 1885), <i>A. raybouldi</i> (Cumberlidge & Vannini, 2004), <i>A. gerdalensis</i> (Bott, 1955) and <i>A. montivagus</i> (Chace, 1953) by the form of the G1TA, which has a rounded low crest arising out of the dorsal lobe in <i>A. unisulcatus</i> (Figs. 4A–C, 5A, C, 9A–C, 10B, C) (versus a G1TA, where a high thin crest arises from the dorsal lobe in <i>A. amosae</i>, <i>A. caputanatis</i>, <i>A. johnstoni</i> (Reed & Cumberlidge 2006: figs. 151, 152), <i>A. raybouldi</i> (Reed & Cumberlidge 2006: figs. 165, 166), <i>A. gerdalensis</i> (Reed & Cumberlidge 2006: figs. 147, 148), and <i>A. montivagus</i>; Chace 1953: fig. 3e–g, j). <i>Arcopotamonautes unisulcatus</i> can be distinguished from <i>A. parekeeae</i> Cumberlidge & Jonas, 1924 and <i>A. ngae</i> Cumberlidge & Jonas, 1924 by the sulci on the anterior thoracic sternum, where the S3/4 is missing except for two short notches at the margins in <i>A. unisulcatus</i> (versus deep and completely traversing the thoracic sternum in <i>A. parekeeae</i> and <i>A. ngae</i> (Cumberlidge & Jonas, 1924: figs. 2B, C, 7B, C)). Finally, <i>A. unisulcatus</i> can be distinguished from <i>A. picus</i> Cumberlidge & Conners, 2025 by the form of the G1TA, which is distinctly widened in the midsection in <i>A. unisulcatus</i> (Figs. 4A– C, 5A, C, 9A–C, 10B, C) (versus slim and tapering to a slightly upcurved tip in <i>A. picus</i>; Cumberlidge & Conners 2025: fig. 4A, B, D–F).</p> |
| title | Arcopotamonautes unisulcatus |
| topic | Biodiversity Taxonomy Animalia Arthropoda Malacostraca Decapoda Potamonautidae Arcopotamonautes Arcopotamonautes unisulcatus |
| url | https://doi.org/10.5281/zenodo.16739563 |