Grismadox, Pett & Rubio & Perger, 2022

Pett, Brogan L., Rubio, Gonzalo D. & Perger, Robert, 2022, Grismadox gen. nov., a new Neotropical genus of ant-resembling spiders (Araneae, Corinnidae, Castianeirinae), including the description of two new species from Bolivia and Paraguay, Zoosystematics and Evolution 98 (1), pp. 1-11 : 1

Genus Grismadox gen. nov.

Type species.

Grismadox karugua sp. nov.

Etymology.

The genus name is a patronym in honor of Cristian Grismado, arachnologist of Museo Argentino de Ciencias Naturales "Bernardino Rivadavia". The letter ‘x’ is taken from the suffix of the genus Mazax with which Grismadox gen. nov. shares some characteristics. Gender is masculine.

Diagnosis.

Grismadox gen. nov. can be separated from all other castianeirine genera by the combination of: (i) COs anterior to ST, (ii) male palp with two distinct RTAs, (iii) an embolus with several coils, (iv) a relatively continuous (not constricted) carapace, and (v) an elongated abdomen.

Comparisons.

Considering carapace and abdomen shape, arrangement and number of tibia I spines, and the petiolated pedicel, Grismadox gen. nov. is morphologically intermediate between Myrmecotypus and Mazax (see Perger and Dupérré 2021 for comments on G. mazaxoides comb. nov.). Particularly the carapace shape, elongated and constricted abdomen, and the sclerotized second pair of pedicellate setae indicate species of Grismadox gen. nov. are closely related to those of Mazax . However, species of Mazax have AME smaller than ALE, a distinctly elongated and rugose petiole and COs posterior to ST I.

Grismadox gen. nov. can be reliably differentiated from Myrmecotypus and Mazax , and other Neotropical castianeirines, by markedly different copulatory structures: embolus with an irregularly multi-coiled screw shape at its apex, coupled with two conspicuous retrolateral apophyses on the palpal tibia, and copulatory openings anterior to the secondary spermathecae. Myrmecotypus jasmineae Leister & Miller, 2014a is the only species of the genus with an embolus with several coils (female not known) (cf. Reiskind 1969; Leister and Miller 2014a; Pett 2021), but it lacks distinct RTAs and an elongate abdomen. Grismadox gen. nov. have elongate abdomens and are ground-dwelling, in contrast with the subglobose abdomens and arboreal habits as in Myrmecotypus . Additionally, Myrmecotypus does not have the second pair of pedicellate setae sclerotized into spines.

Grismadox gen. nov. and some species of Castianeira share the multi-coiled embolus tip and elongated abdomens. However, Castianeira have straight to procurved AER, COs posterior to ST II, and are without dRTA (although some do have a vRTA or a ventral retrolateral protrusion).

Grismadox gen. nov. shares the general habitus, the arrangement of the eyes with the wide and recurved posterior row, strong dorsal scutum on a constricted abdomen with Apochinomma , but can be easily distinguished from this genus by not having a pronounced abdominal petiole a lower number of anterior tibial spines (in Grismadox 2-2, 3-2 or 3-3, in Apochinomma 4-4 or 5-5).

Some species of Myrmecium and Sphecotypus niger (Perty, 1833) have male palps with an embolus with several coils and distinct RTAs. Additionally, a few species of Myrmecium have anterior positioned COs. However, these genera have a very distinctly constricted carapace ( Leister and Miller 2014b; Candiani and Bonaldo 2017).

Other genera with a recurved PER and elongate abdomens include the misplaced Afrotropical species of Corinnomma Karsch, 1880 (Haddad 2006; Raven 2015), but Grismadox gen. nov. has a strongly recurved PER vs. slight, and dRTA and vRTA on the male palpal tibia (vs. absent in those Corinnomma spp.). The monotypic Solomon Islands endemic Melanesotypus Raven, 2015 shares with Grismadox gen. nov. a recurved PER and anterior lateral extremities of carapace subtruncate in females, but has a subglobose abdomen as in Myrmecotypus . Additionally Melanesotypus has a paracymbial spine on the palp of males, no RTAs, in addition to a wide embolic ridge that arises prolaterally leading into a broad sweeping embolus (Raven 2015), all absent in Grismadox gen. nov.

Description.

Small, slender spiders with adults between 3.17 mm and 6.20 mm total length. Carapace generally ellipsoid, truncated at posterior margin, with distinct subrectangular cephalic region (more rectangular in females). Carapace sloping very gently towards highest point, at posterior half of the fovea. PER wider than AER, recurved; eyes subequal, with AMEs only slightly larger than ALEs, maximally about 1.3 × diameter of ALEs; AER recurved. Sternum shield-shaped, between 1.5 × to 2 × longer than wide, widest between coxa I and II, anterior ridge of sternum truncated to weakly recurved. Abdomen ovoid, longer than wide, drop-shaped in males, pear-shaped (broader posteriorly) in females. Second pair of pedicellate setae thickened into spines. Abdomen constricted at around 1/3 its length. Ventral sclerite present in males, rectangular and covering around ½ total length of venter, just posterior to epigastric sclerite, absent in females. Palpal tibia wider than long, with two RTAs, vRTA disto- laterally oriented at between 10'30 to 11'o clock position and longer, dRTA more distally oriented and shorter. Cymbium with basal retrolateral groove that mirrors angle of vRTA. Sperm duct with convoluted median basal loop and more distal wider retrolateral loop. Embolus screw-like, with between two-and-a-half and five clear irregularly to tightly spaced coils before tapering to embolic apex, apex varies from translucent and relatively blunter (as in G. karugua sp. nov.) to well-sclerotized and sharp (all other species). Epigynal plate well-sclerotized. Epigyne relatively simple, ST conspicuous and dark, CO situated anterior to ST, ranging from far anterior ( G. karugua sp. nov. and G. mazaxoides ) to anterolateral ( G. mboitui ). Both ST spherical. ST II larger than ST I.

Composition.

Grismadox baueri sp. nov., Grismadox karugua sp. nov. (type species), Grismadox mazaxoides (Perger & Duperré, 2021) comb. nov. and Grismadox mboitui (Pett, 2021) comb. nov.

Geographical and ecological distribution.

The species of this genus are currently known from the Humid Chaco in southwestern Paraguay and two savanna locations in the area of Chiquitano dry forest and Moxos Plains Flooded Savannas in Bolivia. Judging from observations of live individuals ( Perger and Dupérré 2021) and the occurrence in pitfall samples of G. mboitui comb. nov. ( Pett 2021a), and G. karugua comb. nov. (this paper), species of this genus appear to be epigeal.

Type material examined for comparison.

Mazax ramirezi Rubio & Danişman, 2014: 1185, figs 1A-F, 2A-D, 3A-F, 4A-G, 5A-F (Paratypes ♂ and ♀ from Argentina: Buenos Aires, Campana, January 1998, Fuentes & Di Iorio leg (MACN-Ar 30733/30734).

Myrmecotypus haddadi Perger & Rubio, 2021. Holotype ♂ from Bolivia: Santa Cruz department, Santa Cruz de la Colina, Urubo (-17.760833, -63.24), 432 m a.s.l., 21 Dec 2019, R. Perger leg. (ZMH-A0015356). Paratypes: 1 ♂, same data as holotype (ZMH-A0015357). 1 ♂, 1 ♀, Santa Maria la Antigua (-17.3719, -63.6563), 13 Apr 2018, R. Perger leg. (IBSI-Ara 1463).

Myrmecotypus rubrofemoratus Perger & Rubio, 2021. Holotype ♂ (IBSI-Ara 1507) and ♀ allotype (IBSI-Ara 1467): Bolivia: Santa Cruz department, (-17.469167, -63.6925), 20-22 Jan 2016, R. Perger leg. Paratypes: same data as holotype, 1 ♀ (IBSI-Ara), 3 ♀ (CBF).

Myrmecotypus tahyinandu Perger & Rubio, 2020. Holotype ♂ from Bolivia: Santa Cruz department: Andrés Ibáñez province, La Guardia (-17.8830, -63.3177), 9 Sep 2015, R. Perger leg. (IBSI-Ara1469). Paratypes: Santa Cruz department: Andrés Ibáñez province: 1 ♂, 3 ♀, same location as holotype, between Sep 2015 and Jan 2017 (IBSI-Ara1465). 5 ♂, 6 ♀, same location as holotype, between Sep 2015 and Jan 2017 (CBF). 4 ♂, 5 ♀, Cotoca (-17.7736, -63.065), 11 Jul 2018, R. Perger leg. (CBF). 1 ♂, 1 ♀, Santa Cruz de la Colina (-17.758889, -63.241667), 3 Mar 2019, R. Perger leg. (CBF); 1 ♂, 2 ♀, Arroyo Urubo (-17.7575, -63.251667), 15 Feb 2020, R. Perger leg. (CBF); Lomas de Arena (-17.925, -63.160833), 14 Feb 2020, R. Perger leg. (CBF). Santa Cruz department: Ichilo province: 1 ♂, Cafetal (-17.468333, -63.700278), 20-22 Jan 2016, R. Perger leg. (CBF).

Myrmecotypus iguazu Rubio & Arbino, 2009. Holotype ♂ (MACN-Ar 19708) and allotype ♀ (MACN-Ar 19709) from Argentina: Misiones Province, Iguazú National Park (25°41'S, 54°26'W), 8 January 2009, G. Rubio and M. Arbino leg. Paratypes: same locality, 15 January 2005, G. Rubio leg., 1 ♂ (CARTROUNNE 7818); same locality, 8 January 2009, G. Rubio and M. Arbino leg. 1 ♂ (CDA 000.806), 3 ♀ (CDA 000.807, CDA 000.808, CDA 000.810), 1 ♀ (MLP 17926); same locality, 20 January 2005, G. Rubio leg. 1 ♂ (CDA 000.811); Misiones Province, Urugua-í Wildlife Reserve (25°59'S, 54°05'W), 7 March 2009, G. Rubio leg., 1 ♀ (CDA 000.809).