Argentodromas bellanella, Díaz & Martens, 2018

Díaz, Analia & Martens, Koen, 2018, Psammoecus simonis Grouvelle 1892, Zoological Studies 57 (10), pp. 1-13 : 4-7

Argentodromas bellanella gen. nov., sp. nov.

Díaz and Martens

( Figs. 2-4 )

Type locality: Moconá National Park, Misiones province, Argentina (27°08'S; 53°53'W) (see Fig. 1 ). All material collected by Analía R. Díaz on March 2nd, 2010.

Material examined: Holotype: a male, with soft parts dissected and store with glycerine in sealed glass slides and valves stored dry in a plastic micropalaeontological slide (MLP-Cr 26923). Allotype: a female, dissected and stored as the male (MLP-Cr 26924). Paratypes: 7 females, 3 males (MLP-Cr 26925).

Etymology: The first part of the specific epithet name, “ bella ”, is an adjective that means beautiful in Italian, the second part “ nella ” refers to the mother´s name of the first author (AD).

Diagnosis: Carapace with weak polygonal ornamentation, rounded in lateral view. Eye cups very weakly developed, recognizable mostly because of absence of ornamentation in these spots. Ventral plate like expansion consisting in 3-4 longitudinal rows of rounded elevations. CR with anterior seta present in both sexes. Hemipenis with two shields, ms distally rounded.

Measurements: Males: LV = 619-700 (4, 644 ± 38); H = 408-452 (4, 441 ± 22); RV = 652-690 (4, 660 ± 19); H = 408-428 (4, 426 ± 13). Females: LV = 667-700 (7, 680 ± 14), H = 440-476 (5, 451 ± 17); RV = 650-736 (7, 689 ± 33), H = 490-523 (5, 506 ± 13).

Description: Male valves ( Figs. 2 A-G) smaller than female valves ( Figs. 2 H-L) but similar in appearance. Carapace sub-triangular in lateral view, anteriorly broadly rounded. In both valves, greatest height situated almost in the middle. Surface of valves covered with rather weak polygonal elevations and many pores with setae. Eye cups weakly developed, to almost absent.

Valves sub-equal in dorsal view ( Figs. 2C, K ) with RV slightly bigger than LV. In ventral view ( Figs. 2F, G ) large part of the surface set with 3-4 rows of rounded elevations and bordered with an elevated outer list. Eye tubercles softly pronounced. RV ( Figs. 2E, J ) in inner views, anterior calcified inner lamella broad, posterior one narrower. Selvage largely displaced inwardly in RV ( Figs. 2E, J ), less so in the LV ( Figs. 2D, I ).

A1 ( Fig. 3A ) ñ without sexual dimorphism. First (fused) segment with 2 long ventral setae + 2 short dorsal setae. Second segment with 1 apical seta. Third segment with 2 very short apical setae in both outer and inner side and 2 long apical setae. Fourth segment with 2 long apical setae. 3 long apical setae on fifth segment. Apical (6th) segment with 2 long + 1 short seta and one aesthetasc ya, of c the same length as the setae.

A2 ( Fig. 3B ) ñ. Protopodite with 3 setae. Aestheasc Y long, inserted on first endopodal segment; this segment apically with 5 natatory setae not extending beyond tips of terminal claws, 6th seta shorter. Second endopodal segment with 2 dorsal and 2 ventral apical setae. Third endopodal segment with 3 setae and with G1-claw with a characteristic skewed tip. Aesthetasc (y 1 and y 2 missing). Apical segment with 1 long claw, 1 short claw-like seta and 1 long aesthetasc (y 3) and a seta.

A2 ( Fig. 3C ) ò with 2 + 1 setae on the first segment of the protopodite. Subapical segment with aesthetasc y2 ventrally inserted. Apical segment with 1 long and one shorter claw, 1 short aesthetasc and 1 apical seta fused with the aesthetasc.

Md ( Fig. 3D ) ñ without sexual dimorphism. Coxa with 9 subequal strong teeth. One short smooth seta also present. Mandibular palp with 4 segments. Second segment with 6 plumose ventral “S” setae, two long dorsal setae and three long subapical dorsal seta, this segment also with 4 short apical setae, α- seta smooth and with a relatively broad basis, β- setae plumose and with a swollen basis, γ- seta short and plumose Apical segment with 1 claw-like seta, 2 shorter setae and three smooth long setae of subequal length.

Mx ( Fig. 3E ) ò without sexual dimorphism. With terminal segment of palp subquadrate. First palp segment with 3 apical setae, one of them with a characteristic swollen base. Second segment with 5 smooth setae. Third endite with 6 smooth zahnborsten, a group of 4 dorso-apical setae and one smooth seta ventrally inserted. First endite with 2 serrated setae and with two long hirsute setae laterally inserted. Respiratory plate ( Fig. 3F ) with c 19 rays.

T 1 ( Fig. 3G ) ñ. Endite bearing 11 mostly smooth setae of sub-equal length, d-seta strong plumose and b-seta smooth, two a-setae present, with unequal length and not inserted closely together. Female endopodite (palp) with a single, long seta on top. Males with endopods developed in asymmetrical prehensile palps. Rpp ( Fig. 4A ) with terminal segment banana-shaped with apical sensory organ. First segment longer than the largest width, subapically with 2 short sensory organs. Lpp ( Fig. 4B ) with terminal segment sickleshape and curved, apically with 1 strong sensory organ. First segment large, subapically with 2 short sensory organs.

T 2 ( Fig. 4C ) ò. without sexual dimorphism. Without d-setae. First, second and third segment of endopodite with one apical seta. Terminal segment with one large apical claw, flanked by 2 long apical setae.

T 3 ( Fig. 4D ) ò. without sexual dimorphism. With 3 setae on the first segment and one apical seta on the second segment. Third segment with 1 lateral seta. Terminal segment separated, with 1 long apical claw + 1 seta shorter and a reflexed sub-apical seta.

CR ( Figs. 4E, F ). Relative curved in males, posterior seta long, anterior seta short but always present.

Attachment of CR ( Fig. 4G ) ò. Short, X-shaped.

Hemipenis ( Fig. 4H ) with one long and distally rounded protruding medial shield (ms) and one sub-rectangular lateral shield (ls).

ZO ( Fig. 4I ) ò. Large and well-developed with 14-15 spinous whorls.

Figures

Fig. 2. Argentodromas bellanella gen. nov., sp. nov. Male (MLP-Cr 26923). (A) RV, ext. view; (B) LV, ext. view; (C) Cp, dorsal view; (D) LV, int. view; (E) RV, int. view; (F) Cp, ventral view; (G) detail of anterior part of (F). Female (MLP-Cr 26924). (H) RV, ext. view; (I) LV, int. view; (J) RV, int. view; (K) Cp, dorsal view; (L) detail of muscle scars. Scale bars: A-F, H-K = 200 µm, G, L = 50 µm

Fig. 3. Argentodromas bellanella gen. nov., sp. nov. (A) Female (MLP-Cr 26924) A1; (B) Female (MLP-Cr 26924) A2; (C) Male (MLP- Cr 26923) A2; (D) Female (MLP-Cr 26924) Md; (E) Male (MLP-Cr 26923) Mx1; (F) Male (MLP-Cr 26923) Respiratory plate Mx1; (G) Female (MLP-Cr 26924) T1. Scale bar: A-G = 100 µm.

Fig. 4. Argentodromas bellanella gen. nov., sp. nov. (A) Male (MLP-Cr 26923) Rpp; (B) Male (MLP-Cr 26923) Lpp; (C) Male (MLP- Cr 26923) T2; (D) Male (MLP-Cr 26923) T3; (E) Female (MLP-Cr 26924) CR; (F) Male (MLP-Cr 26923) CR; (G) Male (MLP-Cr 26923) CRa; (H) Male (MLP-Cr 26923) Hemipenis; (I) Male (MLP-Cr 26923) ZO. Scale bars: A-H = 100 µm, I = 50 µm.

Fig. 1. Map showing the position of the sampled stream in the Misiones province, Argentina.