Heterozercon calakmulensis, Klompen & Gerdeman, 2023

Klompen, Hans & Gerdeman, Beverly S., 2023, Genus-level revision of the Heterozerconoidea (Parasitiformes: Mesostigmata), Zootaxa 5322 (1), pp. 1-66 : 34-36

Heterozercon calakmulensis new species

( Figs 14–15 , 37–38 , 67–68 , 84 , 94 )

Diagnosis. Spermatodactyl complex, with a rounded protrusion just below the pointed tip; distance between setae hyp3 and sc subequal to that between hyp3 and hyp 2; sternitiventral shield without distinct ridges; setae Z5 minute, much smaller than S5; ventral and anal shields in male not fused.

Description. Female idiosoma length 834, width 698 (N=1); male idiosoma length 712, width 598 (N=1). All measurements in Tables 3–4 .

Chelicera ( Figs 14–15 ). Basal part of fixed digit in female stout, length width ratio 1–2. 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, of the flaccid type.

Palp. Axial outgrowth of palp trochanter in female and male distinct and membranous. Seta pd1 on femur present. Setae on femur long, thick spines. Seta al2 and pl on genu present. Number of sensilla on palp tarsus 10–11. Formula: 2–6–5–14–10/11.

Gnathosoma ( Figs 37–38 ). Gnathotectum of female without prominent points. Anterior margin gnathotectum not serrate. Overall shape of gnathotectum curved. Sexual differentiation in gnathotectum absent. Lateral lips enlarged to form a trough; posterior extension of the trough long, extending distinctly beyond insertions of setae hyp2. Distance between setae hyp3 and sc subequal to that between hyp3 and hyp2. Setae hyp2 at least twice as long as hyp3. Cornicula membranous without distal notch. Additional setal base-like structure on hypostome present.

Dorsum. Dorsal shield in adults covering most of the dorsum; shield with distinct reticulation. Anterior dorsal margin in adults without elongate setae; setae j1 absent or not distinct (e.g., minute). Antero-marginal area of dorsal shield in males without distinct spines. Median dorsal setae minute. Posterior dorsal setae (Z2–Z4) minute.

Sternal area female ( Fig. 67 ). 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 inserted 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, iv2, and iv3 present. Distinct curved, sclerotized ridge on anterior margin of female genitiventral shield present.

Sternal area male ( Fig. 68 ). Areas near insertion sternal setae st1 sclerotized, forming isolated platelets. Sternal setae st1 and lyrifissures iv1 inserted on the same shield. Sclerotized areas near insertion sternal setae st2 forming isolated platelets. Sclerotized areas of sternal setae st2 and st3 not fused. Sclerotized areas near insertions sternal setae st3 and st5 fused with sternitiventral shield. Sternal lyrifissures iv1, iv2, and iv3 present. Male genital opening presternal. Genital shields not overlapping base of the tritosternum. Sternitiventral area in male relatively smooth, with a few cuticular bumps, otherwise surface faintly reticulate.

Opisthogaster ( Figs 67–68 ). Metapodal and sternitiventral shields in adults not fused. Posterolateral margin of metapodal shields rounded. Setae Zv3 absent. Opisthogastral suckers present, posterior to ventral shield, of heterozerconid type. Secondary genital openings of female on axial side of opisthogastral suckers, associated with a few small sclerites ( Fig. 67 , arrow). Apodemes extending from opisthogastral suckers absent. Ventral shield area with a single shield. Sternitiventral and anal shields in male partly fused, not fused in female. Setae Sv2 not inserted on genitiventral (female) or sternitiventral (male) shield. Setae Sv3 inserted on genitiventral (female) or sternitiventral (male) shield. Setae Jv5 inserted anterior to ventrianal line. Insertion paranal setae (pa) at level of anus. Postanal (po) seta similar in length to paranal (pa) setae. Setae Z5 minute; setae S5, R5 and R4 of medium length. Number of marginal opisthosomal setae small, modified into hook-like spines. Lyrifissures iv5 inserted near anterior margin of suckers. Postero-marginal shield in both sexes wide, extending lateral well beyond opisthogastral suckers.

Legs ( Figs 84 , 94 ). Tibiae and tarsi of legs I of similar width as rest of the leg. Acrotarsus on legs I present. Femora I setae ad3 and pl2 present, setae v3 and v4 absent. Genua I setae ad3 and pd3 absent. Tibiae I seta ad2 present, setae ad3, av2 and pv2 absent. Femora II setae 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 setae ad2, pd3 and pl2 absent. Femora III seta v3 absent. Tarsi IV setae av4 and pv4 absent. Complete chaetotaxy in Table 2 . Both coxae I setae in male distinct spines with rounded tips. Femora I setae al1 and al 2 in male spine-like, in anteroventral position; setae al1 and al 2 in female sturdy setae, not spines. Femora I seta av and pv in male large straight spines; setae av and pv in female spines, but much shorter than in male. Femora II seta al in male spine-like and ventral in position, setae av and pv in male spines; setae av and pv in female much thinner. Genua II seta pv and tibiae II seta pv in male spines, barely half as long as seta av; setae pv in female setiform and as long as av. Tarsi II seta pl1 a spine in both sexes, thinner in female. Trochanters III in male with seta al spine-like, setae av and pl setiform.

Type depository. Holotype male, accession number CNAC 012443 , and female paratype, CNAC 012444 , at CNAC.

Material examined. Mexico: Campeche, Calakmul Biosphere Reserve , Bel-Ha, ~ 150m, 18.9473 N 89.3155 W, 5–Jul-2005, Vázquez, M. M., 1 male, CNAC 012443 , holotype ; same data, 1 female, CNAC 012444 , paratype .

Etymology. The species name is derived from the collecting locality, near the ruins of the ancient Mayan city of Calakmul.

Remarks. Heterozercon calakmulensis differs from H. microsuctus in the shape of the spermatodactyl (with a rounded protrusion near the tip which is absent in H. microsuctus ) and in the size of the opisthogastral suckers (of “standard” size vs. distinctly smaller than average in H. microsuctus ). Distinguishing this species from the Berlese species, H. degeneratus and H. latus , is more problematical given the lack of detail in these older descriptions. It appears that H. degeneratus shares the relatively small opisthogastral suckers with H. microsuctus (as already noted by Fain (1989)) but neither Berlese (1902) or Silvestri (1903) provide sufficient information to distinguish H. calakmulensis from H. latum .

The designation of the medium pair of longer setae on the posterior margin sclerite as S5 is based on comparative observations for other Heterozercon species. Some of these show the same arrangement as H. calakmulensis , in others an added pair of distinctly longer setae is visible internal of, but very close to, the setae here designated as S5. We consider that pair of setae Z5. Because no such setae can be observed in H. calakmulensis we hypothesize that Z 5 in H. calakmulensis are absent or, more likely, reduced to the size of the accessory setae on the sclerite.

Figures

FIGURES 12–15. Heterozerconidae, chelicera males, photograph (top) and composite drawing (bottom): 12–13, Afroheterozercon mahsbergi (OSAL 003045); 14–15, Heterozercon calakmulensis (CNAC 012443).

FIGURES 35–38. Heterozerconidae, gnathosoma, adults: 35, Maracazercon joliveti, female (paratype, #74–71; red arrow: setal base-like structure on hypostome); 36, Maracazercon joliveti, male (paratype; #74–75); 37, Heterozercon calakmulensis, female (CNAC 012444); 38, Heterozercon calakmulensis, male (CNAC 012443). Inset: gnathotectum (female and male) and labrum + salivary stylets.

FIGURES 67–68. Heterozerconidae, Heterozercon calakmulensis n. sp., idiosoma venter: 67, female (CNAC 012444); 68, male (CNAC 012443).

FIGURES 82–86. Heterozerconidae, leg I, male. 82, Afroheterozercon mahsbergi (OSAL 003042, published); 83, Maracazercon joliveti (paratype); 84, Heterozercon calakmulensis n. sp. (CNAC 012443); 85, Allozercon leytensis n. sp. (OSAL 053185); 86, Al. (Philippinozercon) makilingensis (OSAL 0053267, redrawn from Gerdeman et al. (2018)).

FIGURES 93–96. Heterozerconidae, leg II, male: 93, Maracazercon joliveti (paratype); 94, Heterozercon calakmulensis n. sp. (CNAC 012443); 95, Allozercon leytensis n. sp. (OSAL 053185); 96, Al. (Philippinozercon) makilingensis (OSAL 053267, redrawn from Gerdeman et al. (2018)).