Fluctus, Jin & Zhang, 2020

Jin, Chi & Zhang, Feng, 2020, Fluctus gen. nov., a new castianeirine genus from Yunnan, China (Araneae: Corinnidae), Zootaxa 4821 (1), pp. 161-172 : 162-163

publication ID	https://doi.org/ 10.11646/zootaxa.4821.1.9
publication LSID	lsid:zoobank.org:pub:31066E03-01F5-4BE9-97D1-B34F638FB9C2
DOI	https://doi.org/10.5281/zenodo.4398344
persistent identifier	https://treatment.plazi.org/id/1B105A0F-FF95-C307-FF5E-FCFA3E0EFC0B
treatment provided by	Plazi
scientific name	Fluctus
status	gen. nov.

Treatment

Fluctus View in CoL View at ENA gen. nov. (dzdzHOE)

Type species: Fluctus bannaensis sp. nov.

Etymology. The generic name is a Latin word “ fluctus ”, meaning “wave”, referring to the particular wave-shaped pattern on abdomen dorsally. The gender is masculine.

Diagnosis. This new genus differs from all other Castianeirinae genera in the combination of the particular wavy pattern on abdomen dorsally of males and females ( Figs 1A, 1B View FIGURE 1 , 5E View FIGURE 5 ), a paracymbial spine on the cymbium retrobasally of the male palp ( Figs 3C View FIGURE 3 , 6C View FIGURE 6 ), and the large, smooth, unfolded, spherical spermathecae of the female vulva ( Figs 3F View FIGURE 3 , 6F View FIGURE 6 ).

Among those Castianeirinae genera distributed in southern Asian, Fluctus gen. nov. most closely resembles the genus Corinnomma in both possessing a paracymbial spine on the male palpal cymbium, but can be distinguished from it by: 1) the anterior edge of abdomen overhanging the posterior of the carapace ( Fig. 1 View FIGURE 1 C–D), rather than the gradually sloping anterior abdomen in Corinnomma ( Deeleman-Reinhold 2001: fig. 465); 2) the AER in frontal view and PER in dorsal view are obviously procurved ( Fig. 2C, D View FIGURE 2 ), whereas they are both almost straight in Corinnomma ( Raven 2015: fig. 12d); 3) transverse ventral groove present in the male palpal tibia ( Figs 3C View FIGURE 3 , 6C View FIGURE 6 ), whereas it is absent in Corinnomma ( Raven 2015: fig. 13b); 4) secondary spermathecae spherical ( Figs 3F View FIGURE 3 , 6F View FIGURE 6 ), whereas they are folded in Corinnomma ( Deeleman-Reinhold 2001: fig. 468).

Description. Medium sized (7.29–10.23 mm), dark spiders. Carapace dark brown to black, pear-shaped, truncated at posterior margin; arched in lateral view, gently sloping upward from eye area to fovea, highest at fovea, steeply sloping downward posteriorly ( Fig. 1C View FIGURE 1 ); white feathery hairs form broad longitudinal stripe medially from clypeus to posterior margin of carapace, with narrow arc-shaped stripes at fringe (but are often not obvious in ethanol), longitudinal stripe anteriorly as wide as cephalic region ( Fig. 1A, B, D View FIGURE 1 ); widest between coxae II and III, gradually narrowing backwards, straight or slightly concave at posterior margin before pedicel; radial and cervical grooves indistinct; fovea longitudinal, located at centre of thoracic region. Ocular area narrow, about 0.6 times CRW; AER procurved in frontal view, PER procurved in dorsal view; AME largest; ALE smallest, oval; with six long curved setae behind PER ( Fig. 2G View FIGURE 2 ). Clypeus height about 1.5–2 times AME diameter, with three long curved setae arranged in a triangle ( Fig. 2H View FIGURE 2 ), present in both males and females. Chilum present, single, triangular, weakly sclerotized ( Figs 2D View FIGURE 2 , 5H View FIGURE 5 ). Chelicerae same color as carapace; fang mound light color, with long curved setae; promargin with three and retromargin with two teeth. Endites, labium and sternum with same color; endites longer than wide, with light-colored inner edges, short and almost triangular in males; labium wider than long, with light-colored apex ( Fig. 2B View FIGURE 2 ); sternum shield-shaped, longer than wide, precoxal triangles and intercoxal sclerites present. Legs long, with stripes of white hair ( Fig. 1A, B View FIGURE 1 ); all femora black, other segments dark brown; anterior tibiae with three and metatarsi with two pairs of ventral spines. Patellae I–IV with one proximal and one disto-dorsal trichobothria; tibiae I–II with one disto-dorsal trichobothria. Leg formula 4123. Abdomen long ovoid, dark brown to black; with overhanging edge anteriorly ( Fig. 1C View FIGURE 1 ); dorsum with one longitudinal wave-shaped band medially formed by white or pale yellow feathery hairs and no other patches ( Fig. 1A, B View FIGURE 1 ); dorsal scutum in male full length of abdomen, extending onto lateral faces (in F. bannaensis sp. nov.) or even fused to ventral sclerite (in F. tengchongensis sp. nov.) ( Fig. 5A, B View FIGURE 5 ); dorsal scutum in female weak and small, usually one-third of abdomen length or shorter; epigastric sclerite developed in both sexes, forming tube-like collar wrapping pedicel in males and females ( Fig. 5B View FIGURE 5 ); postepigastric and ventral sclerites present in males; inframamillary sclerite small and present in both sexes; pairs of lunate patches on lateral faces of abdomen ( Fig. 2F View FIGURE 2 ); abdomen paler ventrally than dorsally.

Palpal tibia longer than wide, with deep transverse ventral groove ( Fig. 3 View FIGURE 3 A–C); RTA absent; prolateral tibial tubercle triangular. Cymbium with one distinct digitiform retrobasal paracymbial spine on low process ( Figs 3C View FIGURE 3 , 4C View FIGURE 4 , 6C View FIGURE 6 , 7C View FIGURE 7 ), without thick setae on tip. Tegulum pyriform, with thick double-looped sperm duct occupying most area of tegulum. Subtegulum visible on both sides in ventral view, partly membranous ( Figs 3 View FIGURE 3 A–B, 6A–B). Embolus short, helically twisted, coiled less than one turn, with a pointed tip ( Figs 3D View FIGURE 3 , 6D View FIGURE 6 ).

Epigynal region sclerotized, anteriorly with a pair of linear epigynal depression; median plate present, inconspicuous, anterior wide and posterior narrow ( Figs 3E View FIGURE 3 , 4D View FIGURE 4 , 6E, 6D View FIGURE 6 ). Copulatory openings medially situated, small, with sclerotized crescentic ridges. Copulatory ducts narrow and short, diagonally forward to outer base of secondary spermathecae ( Fig. 3F View FIGURE 3 ). Primary and secondary spermathecae large, spherical, without wrinkles ( Figs 3F View FIGURE 3 , 6F View FIGURE 6 ). A V-shaped or Y-shaped fixed sclerite present, connected to dorsal medially of primary spermathecae and posterior margin of epigyne ( Figs 3F View FIGURE 3 , 6F View FIGURE 6 ).