Potamonautes suprasulcatus ( Hilgendorf, 1898 )

Reed, Sadie K. & Cumberlidge, Neil, 2006, Brachyura: Potamoidea: Potamonautidae, Platythelphusidae, Deckeniidae (), Zootaxa 1262 (1), pp. 1-139 : 1-139

12. Potamonautes suprasulcatus ( Hilgendorf, 1898) (Figs. 113–123, 167–168, 184, plate XII)

Telphusa suprasulcata Hilgendorf, 1898: 8–9 , fig. 5, 5a–d.

Telphusa reichardi — Hilgendorf, 1898: 13.

Telphusa suprasulcata var. pseudoperlata Hilgendorf, 1898: 9 .

Telphusa mrogoroense Hilgendorf, 1898: 10 .

Potamon suprasulcatus — de Man, 1898: 438.

Potamon (Potamonautes) suprasulcatus — Rathbun, 1905: 172; Colosi, 1924: 4.

Potamon suprasulcatus — Chace, 1942: 222.

Potamonautes (Arcopotamonautes) suprasulcatus suprasulcatus — Bott, 1955: 270–272, pl. XVII, fig. 1a–d, 40.

Potamonautes suprasulcatus — Cumberlidge, 1998: 204.

Type material examined: TANZANIA: Mrogoro , male lectotype (cw 55, cl 37, ch 21, fw 15 mm) ( ZMB 9037 ) .

Additional material examined: TANZANIA: East Usambara Mountains , Amani, 2 females (one damaged), female (cw 31.9 mm), xii.1926 (A. Loveridge) ( USNM 64103 ) ; male (cw 27.3 mm), male (damaged), ( USNM 64260 ) ; margin of the Serengeti Plains , about 60 m north and a little west of Mbulu, some 300 m from the east coast and about 4°„S of the equator from a small isolated stream arising in a spring, running a 3 km course, finally drying up completely, male (cw 44 mm), ( R. L. Sutton, Jr.) ( USNM 64966 ) ; South Pare Mountains , Gonja , River at Mwembe, female (cw 43.3 mm), 3 juvenile females (cw 28.5 to cw 30.4 mm), 4 juvenile males (cw 20 to cw 30.8 mm), 18 juveniles (cw 10.8 to cw 25.4 mm), ( NMU TRW­EA62.36) ; Uluguru Mountains , river and stream near Bunduzi, 3 males (cw 36.9 to cw 54.4 mm), 2 juvenile females (cws 42.7, 44.2 mm), 1962 ( NMU TRW­EA62.42A) ; Uluguru Mountains , Bunduki, male (cw 36.5 mm), ( NMU TRW­ EA62.42B) ; Uluguru Mountains , Bunduki, 3 males (cw 47.8 to cw 62.1 mm), male (damaged), ( NMU TRW­EA62.42C) ; East Usambara Mountains , Amani, 2 females (cws 39.5, 45.6 mm), female (carapace removed), 2 males (cws 38.3, 53.5 mm), ( NMU TRW1964.01 ) ; East Usambara Mountains , Amani, male (cw 49.1 mm), 1964 ( NMU TRW1964.02 b) ; Northern Iringa , Kilombero River, male (cws 51.2, 56.2 mm), female (cw 49.7 mm), 11.ix.1965 (W. Hausermann) ( NMU TRW1965.05 ) ; East Usambara Mountains , Amani, male (cw 65 mm), 1968 ( NMU TRW1968.01 ) ; Mahenge Mountains , 2 males (cws 36.2, 54.2 mm), 1965 (W. Hausermann) ( NMU TRW1965.01 ) ; Iringa Mountains , 2 males (cws 41.7, 48.1 mm), 22.vii.1965 (W. H.) ( NMU TRW1965.02 ) ; Southern Mahenge , Kilombero River, 2 females (cws 45.3, 52.2 mm), male (cw 43.8, cl 29.3, ch 17.2, fw 12 mm), 11.ix.1965 (W. Hausermann) ( NMU TRW1965.04 ) ; Amani , East Usambara mountains , Nenguruwe Stream, tributary of Sigi River, male (cw 59.7 mm), ix.1965 (J. N. Raybould) ( NMU TRWix.1965.7) ; West Usambara Mountains , Lwandai , near Soni, Mkusu River, male (cw 46.6 mm), female (cw 41.4 mm), 8 juveniles (cw 12.1 to cw 22 mm), 9.vi.1964 (J. N. Raybould) ( NMU TRW1964.04 ) ; West Usambara Mountains , northeast margin, Makangala River below Malo, male (cw 67.8 mm), female (cw 43 mm), juvenile (damaged), juvenile (cw 14.7 mm), 1966 ( NMU TRW1967.10 ) ; Uluguru Mountains , Morogoro, juvenile (cw 14.6 mm), 1.viii.1967 ( NMU TRW1967.12 ) ; Mahnge Region , West Sali River, female (cw 65.1 mm), 8.iv.1967 (J. N. Raybould) ( NMU TRW1967.14 ) ; stream at Mbinga , male (cw 53.8 mm), female (cw 38.5 mm), 29.viii.1967 (J. N. Raybould) ( NMU TRW1967.22 ) ; Ruvuma (= Ruvoma ) River below Matongoro Forest, male (cw 53.5 mm), female (cw 42.7 mm), 2 juvenile males (cws 29, 34.3 mm), 20.viii.1967 (J. N. Raybould) ( NMU TRW1967.18 ) ; Ruvuma (= Ruvoma ) region, Ndengu stream near Litembo mission, 2 males (cw 32.7, 36.1 mm), 2 females (cw 25.8, 31.7 mm), juvenile (cw 14.3 mm), 30.viii.1967 ( T. R. Williams) ( NMU TRW1967.17 ) ; Njombe , Ruhuji River, below falls, 2 females (cw 38.7, 42.4 mm), male (cw 33.3 mm), 9.vi.1968 ( NMU TRW1968.05 ) ; West Songea , Mpandangindo, Lipupuma stream, juvenile female (cw 31.7 mm), juvenile male (cw 26.5 mm), 22.viii.1967 ( NMU TRW1967.19 ) ; Kinda Kibati , Chogo River, female (cw 65.8 mm), 12.xi.1969 ( NMU TRW1971.06 ) ; male (cw 50.9 mm), ( NMU TRW1971.16 ) ; Kilimanjaro , juvenile (cw 18.4 mm), iii.1972 (Joy) ( NMU TRW­JOY iii.1972 a) ; Kilimanjaro , male juvenile (cw 21.7 mm), iii.1972 (Joy) ( NMU TRW­JOY iii.1972 b) ; Kiwira , near Tukuruyu , between Mbega and north end of Lake Malawi, Kipoke River, juvenile (cw 16.9 mm), juvenile male (cw 24.7 mm), 13.xi.1976 ( NMU TRW1973.02 ) ; Kilimanjaro , male (cw 31.5 mm), 2 juvenile females (cw 22.1, 23.1 mm), 3 juveniles (cw 8.7, 11.9 mm), iii.1971 (Joy) ( NMU TRW­JOY iii.1971 b) ; Kilimanjaro , 2 females (cw 21.3, 32.9 mm), 8 juveniles (cw 8 to cw 11.6 mm), iii.1972 (Joy) ( NMU TRW­JOY iii.1972 c) ; Itete , Mwatisa, Mwakareli River, 2 males (cws 31.1, 38.3 mm), 19.ix.1976 ( NMU TRW1973.03 ) ; Chamhawi near Mpwapwa, male (cw 63.7 mm), 19.v.1976 ( T. R. Williams) ( NMU TRW1971.10 ) ; East Usambara Mountains , Amani , male (cw 44.5 mm), (J. N. Raybould); Matumbi , Nambunjo and Muengei Rivers, female (damaged), 4 females (cw 36.2 to cw 46.1 mm), male (cw 51.3 mm), 2 juvenile females (cws 15.4, 18.1 mm), juvenile (cw 13.1 mm), xi.1989 (J. Kingdon) ( NMU TRWxi.1989b) . MALAWI: Misuku , Wilindi Forest, 3 males (cw 16. 90 to cw 35.2 mm), 2 females (cws 21.8, 30.8 mm), 1­16.x.1948 (A. Loveridge) ( USNM 91156 ) . ZAMBIA: 12 km southsoutheast Mpulungu , Lunzua stream, 5 juveniles (cw 9.2 to cw 29.4 mm), 8 juvenile females (cw 16.4 to cw 31.2 mm), 2 subadult females (cws 34, 42.8 mm), subadult male (cw 42.4 mm), 2.vi.1970 ( R. M. Bailey, Balon, Stewart, Ellis) ( USNM 1007382 ) ; Lake Tanganyika , subadult female (cw 35.7 mm) ( USNM 54717 ) .

Diagnosis. Postfrontal crest distinct, granulated, completely crossing carapace; grooves on posterior part of carapace deep, distinct, especially cervical branchial grooves; exorbital, epibranchial teeth low but distinct; anterolateral margin behind epibranchial tooth heavily granulated; subhepatic region of carapace sidewall heavily granulated, suborbital, pterygostomial regions both smooth; ischium of third maxilliped with faint vertical sulcus; thoracic sternal sulcus s3/s4 either faint or missing; episternal sulci s4/e4–s7/e7 all faint; dactylus of major cheliped of adult males broad not arched; first carpal tooth on carpus of cheliped sharp spine; second carpal tooth smaller spine, with no other teeth behind it; ventral margins of merus of pereiopod 1 both distinctly granulated; distal meral tooth large, pointed; terminal article of gonopod 1 long, slim, needle­like; distal third curving outward at 90° angle to longitudinal axis of gonopod, tapering to slender pointed tip; lateral, medial folds both low; distal margin of subterminal segment slightly concave where it meets dorsal membrane; dorsal membrane widest in middle, equally broad on medial lateral margins.

Size. Large, with a pubertal molt between cw 48–50 mm, and an adult size range reaching cw 74.2 mm.

Type locality. Mrogoro , Tanzania .

Distribution. Malawi, Tanzania and Zambia, and the tributaries of rivers flowing into Lake Tanganyika.

Remarks. Specimens of P. suprasulcatus were identified based on direct examination of the type specimen and on the illustrations of the type provided by Hilgendorf (1898) and Bott (1955). The following type specimens were examined by one of us (NC): Telphusa reichardi Hilgendorf, 1898 from Tabora, Tanzania, a subadult female (cw 33.8, cl 23.7, ch 11.4, fw 10 mm) (ZMB 7463); Telphusa suprasulcata var. pseudoperlata Hilgendorf, 1898 from Usambara, Tanzania, a subadult male (cw 32.1, cl 24.3, ch 9.9, fw 9.2 mm) (ZMB 9348); Telphusa mrogoroense Hilgendorf, 1898 from Mrogoro, close to Dares­Salaam, Tanzania, a subadult female (cw 20.8, cl 15.1, ch 7.2, fw 6.1 mm) (ZMB 11377). All of these subadult specimens were considered here to be junior subjective synonyms of P. suprasulcatus . Potamon (Potamonautes) rodolphianus and P. (P.) rothschildi were treated by Bott (1955) as junior synonyms of P. suprasulcatus . We have compared P. suprasulcatus with the male type specimens of P. rodolphianus and P. rothschildi , and conclude that each of these taxa is a valid species. Furthermore, the illustration of the first gonopod of P. rothschildi provided by Capart (1954) is very different in a number of characters from P. suprasulcatus and P. rothschildi should probably be recognized as a valid species.

Natural history and conservation status. This species lives in major rivers and streams. The conservation status of P. suprasulcatus is categorized as least concern (LC) ( Table 4) because it has a range of occurrence and area of occupancy well in excess of the thresholds for vulnerable (VU) ( IUCN 2004). Its population is estimated to be stable based on indirect measures such as the fact that a lot of material has been collected recently from more than one locality (present study; S. Marijnissen pers. comm.) and that it is well represented in museum collections