Ecuazercon cushuimensis, Klompen & Gerdeman, 2023

Klompen, Hans & Gerdeman, Beverly S., 2023, Genus-level revision of the Heterozerconoidea (Parasitiformes: Mesostigmata), Zootaxa 5322 (1), pp. 1-66 : 25-26

Ecuazercon cushuimensis new species

( Figs 6–7 , 27–28 , 46 , 57–58 , 79 , 89 )

Diagnosis. As for the genus.

Description. Female idiosoma length 819 (52), width 808 (62) (N=5); male idiosoma length 725 (18), width 704 (16) (N=5). Complete measurements in Tables 3–4.

Chelicera ( Figs 6–7 ). Basal part of fixed digit in female elongate, length width ratio 4–6. Movable digit in adults with thin, straplike dorsal extensions. Movable digit in female elongate, digit length>6 times basal width. Inside movable digit female with brush-like structure. Excrescences on male chelicera present, interdigital. Spermatodactyl on fixed digit of male chelicera present, of the straight type.

Palp. Axial outgrowth of palp trochanter in female distinct and membranous. Axial outgrowth of palp trochanter in male absent. Seta pd1 on femur present. Setae on femur long, thick spines. Setae al2 and pl on genu present. Number of sensilla on palp tarsus 11–12. Formula: 2–6–5–13–11/12.

Gnathosoma ( Figs 27–28 ). Gnathotectum of female without prominent points. Anterior margin gnathotectum serrate. Overall shape of gnathotectum blunt. Lateral lips enlarged to form a trough; posterior extension of the trough short, not extending beyond insertions of setae hyp2. Distance between setae hyp3 and sc distinctly smaller than that between hyp3 and hyp2. Setae hyp2 subequal in length or slightly longer than hyp3. Cornicula membranous without a distal notch. Additional setal base-like structure on hypostome present.

Dorsum ( Fig. 46 ). Holodorsal shield in female covering most of the dorsum but leaving a wide strip of unsclerotized cuticle laterally and posteriorly, less so anteriorly. Holodorsal shield in male covering entire dorsum. Anterior dorsal margin in female with a single, elongate pair of setae (j1) inserted on the anterior margin of the dorsal shield. Antero-marginal area of dorsal shield in males without distinct spines. Median dorsal setae minute. Posterior dorsal setae Z2–Z4 elongate in both sexes, inserted on the dorsal shield; marginal setae s6 and S1–S3 elongate in females, but not in males. Small peg-like spinose setae in the marginal opisthosomal region of males may be homologous to elongate setae s6 and S1–S 3 in females.

Sternal area female ( Fig. 57 ). Areas near insertion sternal setae st1 sclerotized, forming isolated platelets. Sclerites of sternal setae st1 and st2 not fused. Sternal setae st1 and lyrifissures iv1 not on the same shield. Areas near insertion sternal setae st2 sclerotized, forming isolated platelets. Areas near insertion sternal setae st3 sclerotized, fused to genitiventral shield. Metasternal setae st4 absent. Areas near insertion sternal setae st5 sclerotized, fused to genitiventral shield. Sternal lyrifissures iv1 and iv 3 in adults present. Distinct curved, sclerotized anterior margin of female genital shield absent. Structures suggesting secondary genital openings not observed.

Sternal area male ( Fig. 58 ). Areas near insertion sternal setae st1 sclerotized, fused to sternitiventral shield. Sternal setae st1 and lyrifissures iv1 not on the same shield. Sclerotized areas near insertion sternal setae st2 fused to endopodal shield. Sclerotized areas of sternal setae st2 and st3 not fused. Sclerotized areas near sternal setae st3 and st5 fused with sternitiventral shield. Sternal lyrifissures iv3 present. Male genital opening presternal. Genital shields overlaying base of the tritosternum. Sternitiventral area in male smooth.

Opisthogaster ( Figs 57–58 ). Metapodal and sternitiventral shields in male not fused. Posterolateral margin of metapodal shields in adults rounded. Setae Zv 3 in adults absent. Opisthogastral suckers in adults present, posterior to ventral shield, of the heterozerconid type.Apodemes extending from opisthogastral suckers absent. Ventral shield area with a single shield. Sternitiventral and anal shields in male not fused. Setae Sv2 and Sv3 inserted on genitiventral (female) or sternitiventral (male) shields. Setae Jv5 positioned anterior to ventrianal line. Insertion of paranal setae (pa) at level of anus. Postanal (po) seta of similar length as paranal (pa) setae. Setae Z5 and S 5 in male medium in length, distinct. Lyrifissures iv5 inserted near anterior margin of sucker. Postero-marginal shields in female small, not extending lateral beyond opisthogastral suckers.

Legs ( Figs 79 , 89 ). Tibiae and tarsi of legs I of similar width as the rest of the leg. Acrotarsus on legs I present. Femora I seta ad3 present. Femora I setae v3, v4 and pl2 absent. Genua I setae ad3 and pd3 absent. Tibiae I seta ad2 present, setae ad3, av2, pv2 absent. Femora II seta av2 and pv2 absent. Genua II–IV setae ad3 and pl2 absent. Genua II seta pd3 absent, genua III–IV seta pd3 present. Tibiae II–IV seta pl2 present. Tibiae II–IV setae ad2 and pd3 absent. Femora III seta v3 absent. Tarsi IV setae av4 and pv4 absent. Complete chaetotaxy in Table 2. Coxae I setae in male somewhat spine-like. Femora I setae al1 and al2 setiform, in anterolateral position. Femora I seta av in male a large, curved spine; seta av in female a short, straight spine. Femora II setae al, pl, av and pv in male setiform. Genua II seta pv and tibiae seta pv in male setiform. Tarsi II seta pl1 spine in both sexes. Trochanters III in male with seta al thick seta, seta pv2 spinose, setae av and pl setiform.

Type depository: Holotype male at FMNH , accession number FMNHINS 4449621. Paratypes at FMNH, OSAL .

Material examined. Ecuador, Morona-Santiago, Cushuimi, Rio Cushuime, ca. 150km SE of Puyo, 320m, 2.5208 S 77.7294 W, 4–Jun-1971, Malkin, B., ex male Barydesmus sp. ( Polydesmida : Platyrhacidae ), field code FMJK 71– 1114, host accession number FMNHINS 1320, 1 male (holotype) 1 female (paratype). Same locality, 15–28–May- 1971, Malkin, B., ex seven Camptomorpha dorsalis Silvestri ( Polydesmida : Chelodesmidae )), field code FMJK 71–1118, host accession number FMNHINS 33998, 5 females 3 males; May-1971, Malkin, B., ex Pycnotropis sp. ( Polydesmida : Aphelidesmidae ), field code FMJK 71–1120, 1 male.

Etymology. This specific designation is a combination of Cushuimi, the type locality and “ensis” Latin for “place, locality”.

Remarks. Comparing records for Amyzozercon chocoensis with those of Ecuazercon cushuimensis shows that both localities and hosts clearly differ. Our records of Ecuazercon are limited to the Cushuimi area in Ecuador (east of the Andes), while those of A. chocoensis are limited to the Choco region of Colombia (west of the Andes). Notably, while A. chocoensis showed local host specificity in Choco, E. cushuimensis was found on three different host species in three different families. The current records therefore do not support either local host specificity of E. cushuimensis , or genus level specificity for Amyzozercon . The latter conclusion is supported by the observation that the Barydesmus and Camptomorpha millipedes carrying Ecuazercon also carried a few specimens of Amyzozercon sp. Of course, a more adequate analysis of host specificity will require substantially more collections from different localities and with well identified hosts.

The grouping of the remaining Heterozerconidae is characterized by the reduction of dorsal setae Z2–Z4 to minute (32.1); some marginal opisthosomal setae spine-like (77); the expansion of the postero-marginal shields in the female to well beyond the opisthogastral suckers (80); the presence of seta pl2 on femora I (85; reversed in Narceoheterozercon ); the transformation of setae al1 and al2 on femora I to a spinose shape and to an anteroventral position (103); and the transformation of femora I seta av in the male into large straight spines (104). Notably, most of these characters (except 32, 103) are sensitive to optimization.

Figures

FIGURES 4–7. Heterozerconidae, chelicera males, photograph (top) and composite drawing (bottom): 4–5, Amyzozercon chocoensis (OSAL 106788); 6–7, Ecuazercon cushuimensis (FMNH-INS 4449621).

FIGURES 27–30. Heterozerconidae, gnathosoma, adults: 27, Ecuazercon cushuimensis, female (FMJK 71–1118); 28, Ecuazercon cushuimensis, male (FMJK 71–1114); 29, Amheterozercon amphisbaenae, female (OSAL 052751; red arrow: sclerotized axial extension of palp trochanter); 30, Amheterozercon amphisbaenae, male (OSAL 052761). Inset: gnathotectum and labrum + salivary stylets. Abbreviations: LL, lateral lips.

FIGURES 45–47. Heterozerconidae, idiosoma dorsal: 45, Amyzozercon chocoensis, female (OSAL 106741); 46, Ecuazercon cushuimensis, female (FMJK 71–1118); 47, Afroheterozercon mahsbergi, male (OSAL 003042)

FIGURES 57–58. Heterozerconidae, Ecuazercon cushuimensis, idiosoma venter: 57, female (FMJK 71–1118); 58, male (FMJK 71–1118). Abbreviations: OS, opisthogastral suckers.

FIGURES 78–81. Leg I, male: 78, Discozerconidae, Discozercon derricki (OSAL 004889); 79, Heterozerconidae, Ecuazercon cushuimensis, (FMNH-INS 4449621); 80, Amheterozercon amphisbaenae (OSAL 052763); 81, Narceoheterozercon ohioensis, redrawn from Gerdeman & Klompen (2003).

FIGURES 87–92. Leg II, male, antero-dorsal view: 87, Discozerconidae, Discozercon derricki (OSAL 004889); 88, Discomegistus sp., male, basitarsus IV (FMNH; red arrow: mid-dorsal sensillum); 89, Heterozerconidae, Ecuazercon cushuimensis, (FMJK 71–1118); 90, Amheterozercon amphisbaenae (OSAL 052763); 91 Narceoheterozercon ohioensis, redrawn from Gerdeman & Klompen (2003); 92, Afroheterozercon mahsbergi (OSAL 003042, published).