Arachnothryx costanensis Steyerm.

• Authority

  Maguire, Bassett. 1967. The botany of the Guayana Highland--Part VII. Mem. New York Bot. Gard. 17: 1-439.

• Family

  Rubiaceae

• Scientific Name

  Arachnothryx costanensis Steyerm.

• Description

  Latin Diagnosis - Arbor vel frutex 6-9 m, ramis dense longe sericeo-strigosis; stipulis oblongo-lanceolatis acuminatis 6-9 mm longis basin versus per medium prope apicemque dense strigoso-sericeis supra medium prope margines glabris; foliis petiolatis, petiolis 10-15 mm longis hirsutis; laminis obovato-ellipticis vel oblongo-ellipticis apice acutis vel subacuminatis basi acutis 9.5-17 cm longis 2.5-7 cm latis supra parce vel modice hirsutulis subtus villoso-hirsutulis, venulis tertiariis paullo transverse reticulatis, nervis lateralibus utroque latere 10-12; inflorescentis longioribus quam latioribus, pedunculo principali 7.5 cm longo pilis patentibus elongatis dense villosis; bracteis principalibus subulatis acutis 11 mm longis subtus strigillosis; floribus lateralibus 1 mm longipedicellatis, centralibus ad 3 mm longipedicellatis; calyce hypanthioque 7.5 mm longo, hypanthio oblongo-turbinato 4.5 mm longo 2.5-2.7 mm lato dense hispidulo; calycis lobis 4 aequalibus vel subaequalibus lineari-lanceolatis subacutis 3.2-4 mm longis 0.6-0.7 mm latis extus hispidis intus glabris marginibus hispido-ciliatis, inter lobos glandulis 3-4 in sinubus munitos interpositos, calycis tubo 0.5 mm alto intus glabro extus hispidulo; corollis 23 mm longis hypocrateriformibus tubo 16-18 mm longo basi 2 mm lato fauce 3 mm lato extus superne pilis adscendenti-subadpressis hispido-strigoso intus parte basilari 7.5 mm breviter puberulo deinde superne glabro, lobis 4 suborbiculari-bus fimbriato-crenulatis 4 mm longis 4.2 mm latis inaequaliter pubescentibus extus dense sericeo-strigosis vel tomentosis vel supra medium interdum glabris; staminibus 4 prope apicem tubi ad 7/s longitudinem affixis inclusis, antheris linearibus 4 mm longis, filamentis 0.5 mm longis; stylo 10 mm longo glabro; capsulis 6-7 mm longis 3 mm latis extus hispidulis; seminibus quadratis vel rhomboideis nonalatis ferrugineo-fulvis 0.4-0.5 mm diam complanatis grosse ruguloso-foveolatis angulatis.

• Discussion

  This species differs from Arachnothrix hispidulus Griseb. in the equal or subequal calyx-lobes, longer corolla-tube, stamens inserted near the summit of the corolla-tube, and the sparingly to moderately hirsutulous upper surface of the leaf-blade.