Monoblemma Gertsch, 1941

Monoblemma Gertsch, 1941: 8,

type species Monoblemma unica Gertsch, 1941 10, figs. 9–12 (by monotypy).

Diagnosis. Males of the genus Monoblemma can be distinguished from other Neotropical members of Tetrablemmidae by the absence of a conductor or any process emerging from the base of the embolus. In contrast, genera within the tribe Mattini such as Matta, Caraimatta, and Micromatta, which have a well-developed conductor (see Shear 1978: 18, figs. 40–46; Lehtinen 1981: 150, figs. 313–315; Brescovit & Cizauskas 2019: 408, figs. 3E–F, 13A–F). Additionally, Neotropical species of Tetrablemma possess a small, sclerotized process at the base of the embolus, which is also lacking in Monoblemma (see Martínez, Flórez-Daza & Brescovit 2020: 95, 97, 99, figs. 2A– B, 4C–D, 6D–E). Males of Monoblemma are further characterized by a long, filiform embolus and a spermatic duct that runs directly into the embolus without forming loops (Figs. 3A–D, 5A–D, 7A–D, 12A–D, 16A–D, 20A–C). The females of the genus are characterized by having very large receptacles with internal rounded glands (Figs. 3E–F, 7E–F, 20E, 12 E−F, 15E−F, 20F).

Composition. Four species Monoblemma unicum Gertsch, 1941, Monoblemma cambridgei (Bryant, 1940), Monoblemma becki Brignoli, 1978, and Monoblemma cubaensis sp. nov.

Distribution. From Virgin Islands to Brazil.

Identification key for Monoblemma species

1. Males.............................................................................................. 2

– Females............................................................................................ 5

2. With one single eye or none............................................................................. 3

– With four eyes....................................................................................... 4

3. With a single median eye at the edge of the clypeal declivity (Fig. 1A–B, D).......... Monoblemma unicum Gertsch, 1941

– Without eyes............................................................. Monoblemma becki Brignoli, 1978

4. Copulatory bulb longer than wide, with a flat projection at the base of the embolus........ Monoblemma cubaensis sp. nov.

– Copulatory bulb nearly as long as wide, without projection at the base of the embolus................................................................................................... Monoblemma cambridgei (Bryant, 1940)

5. Central process extremely thin proximally; preanal plate approximately twice as wide as postgenital plate................................................................................... Monoblemma cambridgei (Bryant, 1940)

– Central process wide along its entire length; preanal plate more than twice as wide as postgenital plate............................................................................................. Monoblemma cubaensis sp. nov.